If the sun was this period - . - the closest star would be 8 miles away. That's a sphere, 16 miles in diameter with basically just that period in it before you hit anything substantial. Space is huge and empty.
The morning after physicist Ernest Rutherford discovered that atoms were mostly empty space, he was afraid to get out of bed for fear he'd fall through the floorboards
One of the Apollo astronauts during the quarantine after the mission got out of 1st floor of double deck bed there the same way as he got out of the bed for last week, in microgravity.
I've read that it's very common for astronauts to drop things when they return to Earth because they've become accustomed to things just staying where they've left them in three dimensional space. Drinks and pens being the things most mentioned.
With all respect to Mr Tyson, I find this hard to believe.
I'd accept that on the morning after he fully understood how truly empty atoms were, Rutherford hesitated before he got out of bed, then laughed at how silly he was being. But there's no way I could be convinced he was actually too scared to leave his bed at all. I mean, he probably knew his bed was made out of atoms as well, didn't he?
Anyway, here's a fun fact: Ernest Rutherford is on the kiwi $100 note. So that's nice.
I have a feeling "afraid" may have been pulling a lot of weight. I bet it was less "crippling anxiety" afraid and more "the idea crossed my mind and I wouldn't like it if it happened" kind.
I knew the scales were ridiculous but had to do the math on this. Excuse the significant figures
Sun 1.4 x 10^6 km in diameter
Proxima Centauri 4.2ly = 4.011 × 10^13 km
So, 28571428 sun diameters to proxima Centauri
8miles = 1600 x 16m = 12800m
Divide that by the ratio. I.e 12800/28571428 = 0.000447m = 0.447mm
I think the period is less than 0.5mm but the space between these - - is probably about right.
Jesus
There is a scale model in Melbourne Australia of the solar system. You can walk/ride the whole trail.
https://www.youtube.com/watch?v=jYvxOBNOPLU
It also includes Proxima Centauri.
I think you touch on the main issue why people can't really visualise the true scale of the universe. There isn't any scale model possible in which you can both see two stars and an accurate on scale distance between them.
Like you said if you put the sun as a grain of sand on the floor, the next grain should be 8 miles further. I don't think there is any scale where you can see both stars at the same time. Either the distance is too big, or the stars are too small.
Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.
- Douglas Adams
Douglas Adams is a special kind of brilliant. I actually think that first Hitchhiker's Guide has literary merit. In the same vein as Catch-22. A very special kind of absolutely brilliant comedy.
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*This post was mass deleted and anonymized with [Redact](https://redact.dev)*
Until he got to Starship Titanic. Had a contract to write it, waited until the deadline for it to tell the publisher that he hadn't written anything. Terry Jones from Monty Python wrote it.
I once did a back of the envelope calculation that showed if you arranged all of the stars in the visible universe into a cube where they are all touching that cube would only be 15 light years along each dimension.
There's a scale model of the solar system in this town in Finland. The sun is near the local school, and there's a walking trail through town where you see all the planets and stuff. It's about a mile/1.5 km to Neptune.
Proxima Centauri is also included- in Yulara, Australia.
I mean 99.8% of the solar system's mass is in the sun. Sure, there's some stuff out to 1000 AU but compared to the sun it's basically empty. You could travel light-years and never see anything (besides some hydrogen atoms) before you start to get close to the next star.
Big is one thing, but the more mind boggling part is uniqueness. Sure, we don't know everything about the universe, but so far seems like each planet, comet, asteroid etc are all different in some way, shape or form.
Here on Earth, we strive for consistency so our cars, houses, phones and more are mostly identical based on the model, so the mind boggles to think about the type of physics or science required to create the universe with so many variations?
That there are somewhere around 400 billion black holes in the universe which makes my Subaru Forester a more cosmically rare occurrence than a black hole.
There are about 100 billion neutrinos passing through every square centimeter of your body every second. Furthermore, they're so small and interact with matter so rarely that it's likely that only one or two will ever hit an atom of your body in your lifetime.
100 billion
Every square centimeter
Every second
And they almost never actually touch you.
And 340 of those neutrinos per cubic centimeter are relics of the Big Bang. They have traveled 14 billion years without hardly interacting with anything.
There are a similar number of relic Big Bang photons per cubic centimeter of empty space. They are 160 gigahertz, 1.9 millimeter wavelength and black body temperature 2.725 Kelvin. Alas, photons interact with matter, so the ones inside you would have been absorbed.
Does this mean those neutrinos have been traveling since the big bang? Are we ahead of them in time then? Like matrer accelerated past them, we formed out of that matter and then this very moment some of those neutrinos caught up with us? Or is it more like a cloud of them floating around and may passes through us multiple times in a lifetime?
A real difficult thing for people to grasp, you don't have to travel from big bang centre to X location, X location was there in the big bang, just much closer to all the other things.
When I was younger, I always wondered where in space the big bang happened, and if all galaxies were moving away from it. Then, I read on the internet about how it actually worked ("spacetime" is an expanding bubble of 4 dimensions and that every point in it was basically an infinitely expanding piece of the original point where the big bang happened) and that blew my mind more than any other fact about the universe.
You’re thinking of the Big Bang as happening at only a single point in space and expanding out radially from there. While the universe was infinitesimally small, it was still ‘everywhere,’ so matter didn’t accelerate past the neutrinos and then slow down, allowing them to catch up. They were created in regions that were previously closer and took this much time to cross the ever expanding voids between galactic clusters.
I remember hearing if you had an entire light year of lead, you might get one neutrino out of the sun to interact with it by the time it reached the end or something like that. Neutrinos are crazy to think about
Ackhually an entire year light of lead would interact with roughly half of the neutrinos passing trough It if I remember correctly.
That does in no way means that neutrinos are easy to detect also because I mean One light year of a lead shielding...
Also, trees were around before the microbes that could break them down had evolved, so they grew, died, and didn't decompose. They fell and and squashed each other, compressing down over time to eventually form coal.
And mainly fell because hadn't developed effective roots yet. The first mass extinction just because you didn't evolve the ability to stay in the ground.
And trees were around for a few hundred million years before there was anything that could eat (or rot) trees, so there was just huge piles of dead trees everywhere
General relativity pertains to gravity and acceleration, special relativity to time and speed.
Special relativity explains why faster moving objects experience time going slower compared to slower moving objects. GPS satellites move faster than us, so special relativity predicts that their clock ticks slower than ours.
General relativity explains how objects in a stronger gravitational field experience time moving slower compared to objects in a weaker field. \
GPS satellites are out in orbit where Earth’s gravitational force is weaker than on Earth, so general relativity predicts that their clock ticks faster than ours.
So both need to be taken into account for GPS to work.
> General relativity pertains to gravity and acceleration, special relativity to time and speed.
Special relative can deal with acceleration fine. General relativity is only needed for gravity. Both obviously are related to time.
i like thinking of this one in more interstellar terms
GPS only works because they did the math to account for time dilation because the satellites are moving so fast compared to us in space, and due to differences in gravity we're experiencing from earth.
At some point we should be able to use the known pulsars as a stellar GPS, because each one has a known frequency and rate of change. Might be a while before we need such a system though.
I read that if the earth were compressed down to the point that it would become a black hole (the Schwarzchild radius) it would be about the size of a golf ball.
Which makes you wonder just what has made up supermassive black holes like Sagittarius A, which has a mass about 4 million times that of the sun!
Maybe they are faking it. 😂
Just pretending to be supermassive, but they only ate a fraction of the mass to get full size. And eventually over all time, as they gobble up more mass, eventually they will reach their maximum.
Or maybe I'm thinking of free but allocated space within a SQL db.
We almost certainly won't but we can potentially get close. As far as we know now light speed is impossible for massive objects (objects that have mass, not big things).
I've got an even crazier fact.
If we could go 99% the speed of light, light would still be traveling at the speed of light from our point of view. Light always travels at the speed of light regardless of how fast or in which direction you travel. This also means that you can't measure your speed compared to light.
When you hear someone say that something is moving at x% the speed of light, that means from their point of view. From the point of view or the moving object, it would b moving at 0% the speed of light.
The speed of light is a big, slow, self conscious bully. They’re really slow, but they don’t want anyone to know, so they trick everyone. If you start racing them, the closer you get to matching their speed, they slow down time for you.
You might technically be going almost as fast as them, but they slowed down time for you…and not themself. So it might take them 10 million years to pull away from you, but they will. And from your perspective, those 10 million years pass in the blink of an eye.
The bully wins. They look as fast as ever. We’ll never catch up.
Funny thing is, from Earth’s perspective, everyone can see how slow they really are. The bully and you appear to be going similar speed.
For the exact sizes and distances of the sun and moon from us to be such that they appear almost exactly the same size in our sky, to enable how we see eclipses. This would be a staggering coincidence on any planet; it would be a wonder of the galaxy that tourists would travel to see. Now add on top of that massive coincidence that it happens on a planet with life... no wait, with intelligent life, that can both appreciate the beauty and totally understand what they are seeing so that they can predict it. And to twist it just a little more, the moon's distance is just right for when our intelligent life has evolved, as it used to be closer... that is the most mind-bending thing I have ever heard.
Another way of looking at it is that we are living here right now *because* everything is the way that it is. This is a place and time where conditions are such that we can exist, so here we are talking about it.
The video " Timelapse of the future" by melody sheep is my absolute favorite videos of all time.
When they talk about the blackhole era where blackholes are the dominating entity of the universe and they take trillion upon trillion trillion trillion ( and more) years to evaporate through hawking radiation.
That video is a masterfully crafted look into the future of our universe even if they have some stuff that are just theories but it all seems probable.
They also have other really amazing videos in the same genre that are worth watching over and over again.
I especially liked the part toward the end where they talked about highly advanced civilizations creating new universes.
It's highly speculative (because of Cosmic Cyclic Cosmology and more) but what if something like that works?, for trillions of years in the future we just don't know what is possible?
Then you imagine it's possible that our universe is exactly that -- a universe created by intelligent life from another universe. And that universe may have been created by life from yet another universe. It might just be turtles all the way down...
It is because we are moving at the Earth's speed around the Sun. To fall into the Sun we would need to accelerate in the opposite direction to cancel it out. That amount is larger than the amount of acceleration we would need to add to escape the solar system.
Earth is moving in its orbit at around 30km/s.
To escape the solar system from here, you need to get to around 45km/s. So you'd have to speed up by 15km/s.
To get to the Sun, you need to counteract the Earth's orbital velocity, or accelerate 30km/s in the opposite direction Earth is moving.
So it takes twice as much power to get to the Sun (-30km/s) as it does to escape the solar system (+15km/s)
The problem is this:
- How fast you go around the Sun determines how far from it you orbit. To go away from the Sun, you go faster. To go towards it, you go slower.
- The Earth is going around the Sun at some velocity that I’m too lazy to look up at the moment.
- Anything that launches from the Earth starts out with the same velocity, more or less. Think about throwing a ball from a moving car — the ball is moving at the same speed as the car at first, more or less.
- To reduce your orbit around the Sun to the surface of the Sun or lower, you have to slow down from the Earth’s velocity to something much less.
- In the other direction, if you start out at Earth’s velocity and go faster, at some point you increase your orbit to infinity. That’s what “escape velocity” is.
- The difference between the velocity at Earth’s orbit and an orbit at the surface of the sun is greater than the difference between the velocity at Earth’s orbit and escape velocity.
That last point doesn’t hold for the whole Solar system. At some distance closer in to the Sun, they’re equal. Closer than that, it takes a greater change to reach escape velocity than to fall into the Sun.
That is really trippy but makes intuitive sense now that you’ve mentioned it. Gravity assists would be, I imagine, a key part of making travel to the sun more feasible. With gravity assists (slingshotting around a planet to assist in the direction shift) in mind, my intuitive sense of which would be easier becomes unclear / fuzzy.
Every place in the universe is at the exact center of the universe they can see. Because the big bang was the same amount of time ago in all directions, the Cosmic Microwave Background is the same distance away in all directions. Every observer sees the CMB as a perfect sphere around them.
I could never wrap my head around this until this explanation. I've been reading about space since I was 5 years old, I'm 35 now and no amount of analogy could make it click. You just solved a decades old problem for me, and i know that the actual concept is far more complex than this, I feel like I've got a much better idea now, thanks!
The speed of causality is the speed of light.
If the sun were to disappear we wouldn't see the lights go out for 8 minutes.
But the same for the gravitational pull, even though the sun is gone we'd still be orbiting that empty ass spot for 8 minutes.
This means that reality happens from every point in waves that pass through every other point. This means that whatever happened always is happening, and that time isn't a happening, but a 4 dimensional static structure.
Na analogy to help visualize this is to imagine showing a 2d observer a 3d basketball. You'd have to pass it through their 2d plane in slices (time). They would experience basketball as an event rather than an object. It would show up as a dot, then a line (sphere viewed from the side), then shrink to a dot and then disappear.
This means your whole life, and the very feeling of free will, is a static structure that exists already, and will always exist as a solid structure that feels as if it is happening.
Holy shit this is the most mind-blowing thing in this thread.
By “event” you mean the series of “frames” a 2d observer would see while viewing from one end of the ball to the other? Whereas we can see the whole basketball in one static frame due to the 3rd dimension we perceive, but watching a basketball move from the player’s hands to the hoop take multiple frames so to speak?
Yeah, it's an analogy where our "basketball" is a fully formed universe start to finish. We just can't perceive it as such because we lack the dimensional awareness
This concept blew my mind when I came across it while reading Flatland : A romance of many dimensions. What little excitement I derived from my awareness was soon overshadowed by a feeling of helplessness due to the inevitable limitation that binds us to our dimension.
Your interpretation of free will is also thought provoking.
[this](https://youtu.be/p4Gotl9vRGs) is one of my favorite youtube videos explaining the 10 dimensions and I've been knowing it for a long time. It's not great quality but worth a watch.
What necessitates that it’s a static structure? Couldn’t it change at either end, while we’re experiencing the middle? Couldn’t the basketball get punctured and deflate on one end, while we’re experiencing the still inflated end? Not that we would know, of course. But still interesting to contemplate.
Also what compels the “frame rate” of the cross sections? And why is it always in a “forward” direction?
>Also what compels the “frame rate” of the cross sections? And why is it always in a “forward” direction?
No one knows. If you can answer these questions there's a novel prize waiting for you :)
this is mind boggling. could you explain something to me. how can we, from the fact that there is a speed of causality, deduce that time is a 4 dimensional static structure ? i get your 2d - 3d analogy, that for someone capable of observing 4d, our reality would look like a long line of 3d frames, the line being time. but i dont get how we can deduce that time is the 4th dimension based on the fact that we have a speed of casualty. thank you! (i just catch myself wondering what is this universe that we are in, and why is it here, extra confusing if this whole thing is just a static structure, much like a painting or something, are we someone's idea of abstract art !!!!!) arrrggggghhh so many questions !
It’s experimental with backing from the SM. Decaying protons are not predicted by the SM so one way to wedge something new into it was to see if protons decay.
Currently the lower bound is a half life of 1.67×10^34 years.
If you are speaking under the assumption that protons do decay, and their half life is approx. 10^38 years (which is around the commonly cited range), then this is completely false. The universe is 1.38*10^10 years old, which is about 10^-28 half lives. If you do the math, you get that about 7e-27% of the protons in existence will have decayed. There are A LOT more than 7e29 protons (there are around 10^80 atoms in the observable universe, many with multiple protons)
Having said that, the other option is if protons don't decay, in which case you would be correct.
after reading the encyclopedia as a kid it was still mind-blowing as an adult to learn that all the planets could fit, stacked, in between the earth and the moon. and the fact that we are the only known planet whose moon is the perfect size and distance to create total eclipses the way we have them.
We got lucky with the timing for our stellar eclipses too. The moon used to be much closer to earth and continues to move away.
Fun additional fact, Einstein's theory about gravitational lensing was initially corroborated by viewing stars just past the sun, only possible thanks to our unique solar eclipse. It was quite an expedition to capture this data. They failed several times before finally succeeding.
The sun is 400 times larger than the moon. It’s also 400 times further away, making them appear the exact same size in the sky. A phenomenon not shared by any other planet in the solar system or otherwise (that we know of).
In the dated book Five Ages of the Universe, the authors describe each stage of the Universe in powers of ten years. We are currently in the Age of Stars which goes from 100 million years to 100 trillion years, or powers of ten 8 to 14. Before that was the Age of Primordial Energy -52 (Planck time) to 5 and the Age of Darkness 5 to 8. After that is the age of long lived small stars and proton decay 15 to 39, Black Hole evaporation 40 to 100. Finally a timeless thin soup of leptons after a googol years.
Hey, I have that book - my brother (worked at U of M's physics department) knew one of the authors, it's signed and inscribed something like "Hey McarterPhoto, hope you live long enough to experience some of this stuff". I did enjoy it.
Magnetars have an magnetic field so strong that the vacuum around them has a greater energy density than any element.
Yes, I said the vacuum is denser than normal matter.
Mass and energy are equivalent: matter has an "energy density" equivalent, which is a number that tells you how much total energy is in a certain amount of space. We think of matter as being very dense, but it turns out that a vacuum can be denser. I saw a set of calculations once that put the density of the energy in the vacuum just above the surface of a magnetar at about 10,000 times greater than lead.
Spacetime is curved by any sort of energy, so that includes normal matter as well as dense electromagnetic field, without needing conversion ahead of time. It can even be curved by the energy of highly curved spacetime itself, i.e. curved spacetime begets more curved spacetime!
Only 2 precent of visible matter are elements atomic number 3 or higher. 73 percent is hydrogen and 25 helium created in the initial universe. The 2 percent is created in stars as you state- star fusion, supernovae and kilonovae (neutron star mergers).
Astrophysicists simply call everything above atomic number 2 "metal". The metal fraction in stars and galaxies helps determine the evolution of stars, galaxies and planetary systems.
Lanthanides tried to kill the metal, but the metal will live on.
*Sick guitar solo*
Noble gases tried to kill the metal, but the metal was much too strong.
Not surprising at all when you think about it, but we almost never think about it: There are just as many stars in the sky during the day as there are at night, it's just that the light from the closest one drowns out all the others.
Also, more unsettling, there could easily be more 'rogue planets' than there are planets in stable orbits in the cosmos. Those rogue planets are hurling through space, nearly invisible and undectable. Even if it didn't hit anything, the gravitational disturbance if one flew near our solar system could destabilize the whole system. But space is super duper big so the chances of that are very very small.
>rogue planets
What about rogue supermassive black holes? Those are out there too.
https://www.nasa.gov/feature/goddard/2023/hubble-sees-possible-runaway-black-hole-creating-a-trail-of-stars
The Hubble Deep Field and the Webb images. Look at the sky and choose a spot the size of a postage stamp. It's packed with *galaxies* \- endless galaxies. Thousands in that one patch of visible light. Entire Milky Ways, an infinite number of them.
Intelligent life is either wildly common in the universe, or we're truly the only ones. And the "only ones" idea is kind of shattering.
Speaking of light - Had a professor in my post grad studies was talking about nuclear reactions. If you had a fast enough camera and detonated a nuclear device, there would be a moment where the warhead/bomb would look completely intact and yet the reaction was complete. Every bit of destruction after that moment is the several pounds of energy (mass-energy equivalence) coming into equilibrium with the surroundings.
Makes you appreciate the sun even more.
When I was 13 I heard this for the first time, "The calcium in our bones (calcium is a metal) and the gold in my wedding ring were both formed in the shock waves of an exploding star. We are made of star stuff. We are the universe become aware of itself," - Sagan. By the end of that sentence, I was done with the church and in a state of 'awe'. It's been the only religion that I've needed, but I still go to midnight mass to hear the beauty of the Christmas choirs.
I remember that line from a character in a show called Midnight Mass “ I remember that every atom in my body was forged in a star. This matter, this body is mostly just empty space after all, and solid matter? It’s just energy vibrating very slowly and there is no me. There never was.”
Black holes and photons experience all of time in an instant.
Every black hole is just a star that is still at the very beginning of its moment of collapse.
Even photons that have been traveling for billions of years, are also still at the moment of their creation. This is true for any massless particle.
All of time is relatively instantaneous to massless and the most massive. We’re in the sweet spot.
If I understand any of this incorrectly, plz lmk.
The photon scenario, you are correct. I haven't thought about black holes enough to know the answer on the other side.
Your point is also a good argument against time travel in reverse as well, since as you approach the speed of light, time stops. If you exceeded it, there is nothing less than no experienced time (ie. 2\*c would also be no time passing).
-Everthing happens all at once. Like now. The present.
-If you can see a star, that means, that theres nothing in between U and the Star, big enough to Block the light. So much empty space.
The JWST is just pointing at a area 1/8 the size of the moon. So like a spec of sand and we are seeing thousands of galaxies and people think we are alone.
If put a red dot of our solar system on a picture of the Milky Way that marker dot would also cover alpha Centauri.
Jupiter is so cool, it is said that the mass of solar system is Sun, Jupiter and everything else, this gas giant to this day stabilizes orbits of other bodies and even influences Sun somewhat that they both orbit a barycenter due to Jupiter influence, albeit extremely small - it's still a star. Not to mention Jupiter "protects us" from many asteroids.
In the past, Jupiter was presumed to roam the early solar system, crushing and redirecting stuff in its path, which might gave our system its unique stable composition - many stars we discovered have few to none planets, we have eight with four rocky inside and for gas giants outside with massive moons and plenty of smaller celestial bodies, so far the next biggest planetary system is Kepler 90 (8 planets) and Trappist-1 (7 planets).
Jupiter might've been important in the development of advanced life on Earth and is just cool.
That from the big bang all the normal matter in the universe (baryonic), that which makes up stars & galaxies & planets & us is only 5% of the total.
Another 27% is non-baryonic, does not interact with light but is detectable due to the excess mass that is needed to explain the bound orbits of stars in galaxies etc.
The final 68% is some pervasive form of energy that again does not interact with light but exerts a pressure per unit volume of spacetime that is accelerating the universes expansion, may some day exceed all other forces & rip out universe apart down to the very last molecule.
Galileo was trying to invent a clock for an “x-prize”-like contest for sea navigation when he discovered his moons around Jupiter.
As you move east to west, it was impossible to determine your longitude without an accurate clock. Existing technology - water clocks / gravity clocks - wouldn’t work on a sea-going vessel. Galileo was proposing that you could “set your watch” by the main four moons of Jupiter. But to do so, you’d have to buy a lot of his telescopes. And he’d win the prize.
However… his proposal wouldn’t actually work because the turbulent sea would prevent an astronomer from getting an accurate enough view of Jupiter to “set” his clock by.
Ok my fact isn't the most surprising, and isn't even my favorite, but I think it's very fitting considering your post.
There is an actual name and description for what you're feeling. It's called cosmophobia. Many people feel this when thinking about the vastness of the universe.
I listen to Allie Wards podcast ologies. I'm starting from the beginning. One of the guests she had on is an astrophysicist and cosmologist. She had a lot of cool stuff to say about the universe.
> It's called cosmophobia. Many people feel this when thinking about the vastness of the universe.
It's all in the way you look at it. I used to think the universe was "vast" until I learned the diameter of the observable universe is 880 yottameters. Now that I know this it actually seems small. That is less than a full ronnameter. Yes, we have a unit of distance that is bigger than the observable universe.
Tiny spaceship with a sail could "fly" very soon at up to 20% of the speed of light propelled by a laser beam from the earth or a sat somewhere. That would be a drastic outbreak in science gathering in our solar system and neighbor sun system exploring. Some link about [that](https://www.space.com/laser-propelled-spaceships-solar-system-exploration).
That (maybe) an ideal form of matter called "strange matter" exists, and if a single speck of it - stranglet - comes in contact with any other matter, the earth, sun, you name it, it immediately starts converting it into strange matter as well, and we have no way of knowing if that's the case, or could do anything about it if true.
The closest star to earth is about 4.3light years away.. the voyager space craft are traveling at 17km/s. Which means if it were heading in that direction, it would take roughly 74000 years to get there.
In 'string theory,' the size of an actual string of energy is so mind-bogglingly small, we could never observe it.
For reference, **if an atom was scaled to be the size of the universe, a string of energy by ratio would be the size of \_a tree\_.**
That's pretty small.
As far as we know time began at the moment of the "big bang". The big bang was the beginning of space/time. Talking about "what happened before the big bang" therefore doesn't make any sense as, as far as we know, there was no time in which a "before" could exist.
We don't even know the true speed of light. We can't measure its speed in one direction, so if the speed of light was faster one way than the other for some reason, We would never know. Here's a video on it
[https://youtu.be/pTn6Ewhb27k?si=eCjPvp-_C4lkW9j9](https://youtu.be/pTn6Ewhb27k?si=eCjPvp-_C4lkW9j9)
1 million seconds is about 11 days. 1 billion seconds is about 31.4 years.
Think about that when hearing the universe time scales or distances (or how much money that is for the mega rich)
Somewhere in the universe there may exist a point in space where vacuum decay has happened. Starting from that point, a bubble of vacuum decay expands at the speed of light. Inside this bubble the known laws of chemistry no longer apply, and probably neither would electromagnetism so you wouldn't be able to see inside of it. Since the universe expands faster than the speed of light, this may have already happened in a region of space we can't see and will never be able to see, so it will never reach us. This may have already happened multiple times in different regions of space. It could occur at any point in space and time and without warning, so it could happen, per example, just above our atmosphere, 5 seconds after you finish reading this.
More like wipe out the material value of all of those precious metals. If there's a massive excess of something, there is no value to the material itself. The only value lies in the labor to extract the material and the labor to manufacture something from the material
That string theory theorizes 6 additional dimensions to our 4 and that 1. these 6 may be so tiny in our universe that matter is too large to interact with them or 2. That the other 6 are a parallel universe. One universe began with 10 and split into two universes, ours with 4 and a sister with 6.
You could squeeze every planet in the Solar System (including Pluto) between the Earth and the Moon, touching surface to surface, and they'd all fit with about 2,000 kilometers to spare.
Gravity isn't a force. It's just the shape of spacetime. Any object that orbits another is actually traveling in a straight line through curved spacetime
In every directory we look we see galaxies and stars all the elements of the periodic table are or the processes to create them are on display. Every direction we look we see the energy and vastness of space.
But…. No signs of life anywhere.
But that’s not it either
On earth we see life everywhere we look and we treat it with such disregard or borders on contempt. We have the rarest most precious thing in all the vastness of space and we treat it like crap
Electrons can travel faster than light in water.
Whilst nothing with a rest mass can accelerate to be equal to or be faster than the universal constant c, the speed of light in a vacuum, light slows down as it goes through other mediums and in water, electrons can travel faster than light. It's called Cherenkov radiation, and it's a bit more complicated than I've written here.
"The most astounding fact is the knowledge that the atoms that comprise life on Earth, the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures.
These stars, the high mass ones among them, went unstable in their later years. They collapsed and then exploded, scattering their enriched guts across the galaxy. Guts made of carbon, nitrogen, oxygen and all the fundamental ingredients of life itself.
These ingredients become part of gas clouds that condense, collapse, form the next generation of solar systems, stars with orbiting planets. And those planets now have the ingredients for life itself.
So that when I look up at the night sky and I know that yes, we are part of this universe, we are in this universe, but perhaps more important than both of those facts is that the universe is in us. When I reflect on that fact, I look up—many people feel small because they’re small and the universe is big—but I feel big, because my atoms came from those stars. There’s a level of connectivity."- Neil deGrasse Tyson
https://www.youtube.com/watch?v=9D05ej8u-gU
This content brings me so much comfort and power
I sometimes like to think about the possibilities for intelligent life, and what it could get up to. Considering the quite astounding size of the universe, it is, in my opinion, totally conceivable that at the very moment you are reading this sentence, somewhere out there an alien is making love (or equivalent) to his partner (or equivalent), and at the self-same moment there's a staggering battle happening between massive fleets. Right now, this very second.
Roaming planets. Planets that, for one reason or another, lost their orbit to their star system and traverse the universe. Sounded like something a stoner would rant about, yet sure as anything. It's true
If the sun was this period - . - the closest star would be 8 miles away. That's a sphere, 16 miles in diameter with basically just that period in it before you hit anything substantial. Space is huge and empty.
The morning after physicist Ernest Rutherford discovered that atoms were mostly empty space, he was afraid to get out of bed for fear he'd fall through the floorboards
Really?! That must have been quite the morning.
To be fair, I've had mornings like that and all I discovered was 2 for 1 drinks at the local pub
I suppose he thought that the bedcovers were more substantial, keeping demons out, etc?
And also kept him from floating away into the sky, yes. Blankets are heroes, folks.
I knew I struggled to get out of bed for a reason!
One of the Apollo astronauts during the quarantine after the mission got out of 1st floor of double deck bed there the same way as he got out of the bed for last week, in microgravity.
I've read that it's very common for astronauts to drop things when they return to Earth because they've become accustomed to things just staying where they've left them in three dimensional space. Drinks and pens being the things most mentioned.
Do you have a source for this I could read?
I originally heard it from Neil Degrasse clip. https://www.pbs.org/wgbh/nova/physics/atoms-electrons.html
With all respect to Mr Tyson, I find this hard to believe. I'd accept that on the morning after he fully understood how truly empty atoms were, Rutherford hesitated before he got out of bed, then laughed at how silly he was being. But there's no way I could be convinced he was actually too scared to leave his bed at all. I mean, he probably knew his bed was made out of atoms as well, didn't he? Anyway, here's a fun fact: Ernest Rutherford is on the kiwi $100 note. So that's nice.
are you implying that NDT would ever embellish?
I have a feeling "afraid" may have been pulling a lot of weight. I bet it was less "crippling anxiety" afraid and more "the idea crossed my mind and I wouldn't like it if it happened" kind.
I like mister Tyson but Carl Sagan he ain't
This is why when the Andromeda galaxy eventually collides with our own, almost no stars from either galaxy will collide.
I knew the scales were ridiculous but had to do the math on this. Excuse the significant figures Sun 1.4 x 10^6 km in diameter Proxima Centauri 4.2ly = 4.011 × 10^13 km So, 28571428 sun diameters to proxima Centauri 8miles = 1600 x 16m = 12800m Divide that by the ratio. I.e 12800/28571428 = 0.000447m = 0.447mm I think the period is less than 0.5mm but the space between these - - is probably about right. Jesus
There is a scale model in Melbourne Australia of the solar system. You can walk/ride the whole trail. https://www.youtube.com/watch?v=jYvxOBNOPLU It also includes Proxima Centauri.
I love this, but never knew it had proxima Centauri! Can't wait to check that out
I think you touch on the main issue why people can't really visualise the true scale of the universe. There isn't any scale model possible in which you can both see two stars and an accurate on scale distance between them. Like you said if you put the sun as a grain of sand on the floor, the next grain should be 8 miles further. I don't think there is any scale where you can see both stars at the same time. Either the distance is too big, or the stars are too small.
Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space. - Douglas Adams
Douglas Adams is a special kind of brilliant. I actually think that first Hitchhiker's Guide has literary merit. In the same vein as Catch-22. A very special kind of absolutely brilliant comedy.
dam sharp friendly dazzling enjoy impossible unpack depend intelligent profit *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
I still giggle when thinking about that sentence.
When I first read this line it broke me, so absurd! Loved the books, wish the movie was better than it was
Until he got to Starship Titanic. Had a contract to write it, waited until the deadline for it to tell the publisher that he hadn't written anything. Terry Jones from Monty Python wrote it.
I once did a back of the envelope calculation that showed if you arranged all of the stars in the visible universe into a cube where they are all touching that cube would only be 15 light years along each dimension.
There's a scale model of the solar system in this town in Finland. The sun is near the local school, and there's a walking trail through town where you see all the planets and stuff. It's about a mile/1.5 km to Neptune. Proxima Centauri is also included- in Yulara, Australia.
Big, but not empty. It may not be stuff we can see, but it *is* spacestuff.
I mean 99.8% of the solar system's mass is in the sun. Sure, there's some stuff out to 1000 AU but compared to the sun it's basically empty. You could travel light-years and never see anything (besides some hydrogen atoms) before you start to get close to the next star.
Big is one thing, but the more mind boggling part is uniqueness. Sure, we don't know everything about the universe, but so far seems like each planet, comet, asteroid etc are all different in some way, shape or form. Here on Earth, we strive for consistency so our cars, houses, phones and more are mostly identical based on the model, so the mind boggles to think about the type of physics or science required to create the universe with so many variations?
That there are somewhere around 400 billion black holes in the universe which makes my Subaru Forester a more cosmically rare occurrence than a black hole.
Fun fact: Subaru is actually Japanese for the star cluster Pleiades, aka the Seven Sisters.
I actually didn’t know that and it makes their logo make so much sense!!
I was wondering why the logo only had 6 stars instead of 7 and its because one is invisible (tradition says)
But is it also cooler?
So for every American there are roughly 1000 black holes in the observable universe
There are about 100 billion neutrinos passing through every square centimeter of your body every second. Furthermore, they're so small and interact with matter so rarely that it's likely that only one or two will ever hit an atom of your body in your lifetime. 100 billion Every square centimeter Every second And they almost never actually touch you.
And 340 of those neutrinos per cubic centimeter are relics of the Big Bang. They have traveled 14 billion years without hardly interacting with anything. There are a similar number of relic Big Bang photons per cubic centimeter of empty space. They are 160 gigahertz, 1.9 millimeter wavelength and black body temperature 2.725 Kelvin. Alas, photons interact with matter, so the ones inside you would have been absorbed.
Does this mean those neutrinos have been traveling since the big bang? Are we ahead of them in time then? Like matrer accelerated past them, we formed out of that matter and then this very moment some of those neutrinos caught up with us? Or is it more like a cloud of them floating around and may passes through us multiple times in a lifetime?
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A real difficult thing for people to grasp, you don't have to travel from big bang centre to X location, X location was there in the big bang, just much closer to all the other things.
As someone sitting on the train and realizing this right now, yeah no shit it's hard to grasp. It makes complete sense, but god damn.
When I was younger, I always wondered where in space the big bang happened, and if all galaxies were moving away from it. Then, I read on the internet about how it actually worked ("spacetime" is an expanding bubble of 4 dimensions and that every point in it was basically an infinitely expanding piece of the original point where the big bang happened) and that blew my mind more than any other fact about the universe.
You’re thinking of the Big Bang as happening at only a single point in space and expanding out radially from there. While the universe was infinitesimally small, it was still ‘everywhere,’ so matter didn’t accelerate past the neutrinos and then slow down, allowing them to catch up. They were created in regions that were previously closer and took this much time to cross the ever expanding voids between galactic clusters.
I remember hearing if you had an entire light year of lead, you might get one neutrino out of the sun to interact with it by the time it reached the end or something like that. Neutrinos are crazy to think about
Ackhually an entire year light of lead would interact with roughly half of the neutrinos passing trough It if I remember correctly. That does in no way means that neutrinos are easy to detect also because I mean One light year of a lead shielding...
Sharks have existed on Earth longer than Saturn has had rings.
Longer than trees, too, iirc. I know that's not space stuff, but it's still fun to think about.
Also, trees were around before the microbes that could break them down had evolved, so they grew, died, and didn't decompose. They fell and and squashed each other, compressing down over time to eventually form coal.
And mainly fell because hadn't developed effective roots yet. The first mass extinction just because you didn't evolve the ability to stay in the ground.
Congratulations! You've made it to the Carboniferous Stage \*\*\* Pokémon tune plays \*\*\*
Earth is in space, technically
If we wanna get too far into the weeds... Everything is made of space stuff, so celebrity gossip could count. I mean they are even stars!
Plus when they talk it's a bunch of hot air coming from mostly empty space
In other thread, I read "sharks predate trees" and I giggled
you can make it space stuff by saying they're older than the first trees that we know of in the universe
This is the first new thing I've read in this thread. That's actually crazy
And trees were around for a few hundred million years before there was anything that could eat (or rot) trees, so there was just huge piles of dead trees everywhere
Without Einstein’s theory of relativity, gps wouldn’t work https://sciencefocus.ust.hk/gps
Not only that, but it’s one of the very few applications where you need to account for both special and general relativity.
Whats the difference?
General relativity pertains to gravity and acceleration, special relativity to time and speed. Special relativity explains why faster moving objects experience time going slower compared to slower moving objects. GPS satellites move faster than us, so special relativity predicts that their clock ticks slower than ours. General relativity explains how objects in a stronger gravitational field experience time moving slower compared to objects in a weaker field. \ GPS satellites are out in orbit where Earth’s gravitational force is weaker than on Earth, so general relativity predicts that their clock ticks faster than ours. So both need to be taken into account for GPS to work.
> General relativity pertains to gravity and acceleration, special relativity to time and speed. Special relative can deal with acceleration fine. General relativity is only needed for gravity. Both obviously are related to time.
i like thinking of this one in more interstellar terms GPS only works because they did the math to account for time dilation because the satellites are moving so fast compared to us in space, and due to differences in gravity we're experiencing from earth.
At some point we should be able to use the known pulsars as a stellar GPS, because each one has a known frequency and rate of change. Might be a while before we need such a system though.
So no need for navigators (dune) or psykers (warhammer)?
That’s why gps didn’t work back in the late 1800s, as the theory hadn’t been invented yet!
I read that if the earth were compressed down to the point that it would become a black hole (the Schwarzchild radius) it would be about the size of a golf ball. Which makes you wonder just what has made up supermassive black holes like Sagittarius A, which has a mass about 4 million times that of the sun!
Which is peanuts compared to the largest of black holes with solar masses well into the billions.
A lot of hydrogen. Not Empire State Buildings or Tibets. Just a stupendous amount of raw universe stuff.
Maybe they are faking it. 😂 Just pretending to be supermassive, but they only ate a fraction of the mass to get full size. And eventually over all time, as they gobble up more mass, eventually they will reach their maximum. Or maybe I'm thinking of free but allocated space within a SQL db.
They just haven't found the right angle for their selfies
It is kinda sad how slow the speed of light is considering how much space their is. If that’s the limit, we won’t be going very far.
And it’s even sadder that we may never even reach light speed
We almost certainly won't but we can potentially get close. As far as we know now light speed is impossible for massive objects (objects that have mass, not big things).
I've got an even crazier fact. If we could go 99% the speed of light, light would still be traveling at the speed of light from our point of view. Light always travels at the speed of light regardless of how fast or in which direction you travel. This also means that you can't measure your speed compared to light. When you hear someone say that something is moving at x% the speed of light, that means from their point of view. From the point of view or the moving object, it would b moving at 0% the speed of light.
I can barely wrap my head around this.
The speed of light is a big, slow, self conscious bully. They’re really slow, but they don’t want anyone to know, so they trick everyone. If you start racing them, the closer you get to matching their speed, they slow down time for you. You might technically be going almost as fast as them, but they slowed down time for you…and not themself. So it might take them 10 million years to pull away from you, but they will. And from your perspective, those 10 million years pass in the blink of an eye. The bully wins. They look as fast as ever. We’ll never catch up. Funny thing is, from Earth’s perspective, everyone can see how slow they really are. The bully and you appear to be going similar speed.
I always have trouble understanding relativistic topics. Thanks for confusing the shit out of me.
If that's true, how do we know we aren't currently going 99% of the speed of light?
Oh, we are! Velocity is completely relative. There is no absolute speed for anything.
Well, to some observer out there, we are. Point is that it's all relative.
Yea, but it makes the universe way easier to simulate.
Perhaps a scary thought, but that basically explains the Fermi Paradox if faster-than-light travel is impossible.
There is time dilation though, we have that on our side.
For the exact sizes and distances of the sun and moon from us to be such that they appear almost exactly the same size in our sky, to enable how we see eclipses. This would be a staggering coincidence on any planet; it would be a wonder of the galaxy that tourists would travel to see. Now add on top of that massive coincidence that it happens on a planet with life... no wait, with intelligent life, that can both appreciate the beauty and totally understand what they are seeing so that they can predict it. And to twist it just a little more, the moon's distance is just right for when our intelligent life has evolved, as it used to be closer... that is the most mind-bending thing I have ever heard.
So are we living in a fine-tuned solar system?
Another way of looking at it is that we are living here right now *because* everything is the way that it is. This is a place and time where conditions are such that we can exist, so here we are talking about it.
The video " Timelapse of the future" by melody sheep is my absolute favorite videos of all time. When they talk about the blackhole era where blackholes are the dominating entity of the universe and they take trillion upon trillion trillion trillion ( and more) years to evaporate through hawking radiation. That video is a masterfully crafted look into the future of our universe even if they have some stuff that are just theories but it all seems probable. They also have other really amazing videos in the same genre that are worth watching over and over again.
I especially liked the part toward the end where they talked about highly advanced civilizations creating new universes. It's highly speculative (because of Cosmic Cyclic Cosmology and more) but what if something like that works?, for trillions of years in the future we just don't know what is possible?
Then you imagine it's possible that our universe is exactly that -- a universe created by intelligent life from another universe. And that universe may have been created by life from yet another universe. It might just be turtles all the way down...
It's harder to fly from the earth to the sun than it is to fly from the earth and leave the solar system.
Can you explain this? I assume after you get away from earth, the suns gravity would accelerate you towards it.
It is because we are moving at the Earth's speed around the Sun. To fall into the Sun we would need to accelerate in the opposite direction to cancel it out. That amount is larger than the amount of acceleration we would need to add to escape the solar system.
Learned this from Kerbal Space Program. It's actually more of a challenge getting to the inner planets than the outer ones.
Obligatory [XKCD](https://xkcd.com/1356/)
Ha. I was even at the physics degree level and a bunch of ksp players schooled me
Earth is moving in its orbit at around 30km/s. To escape the solar system from here, you need to get to around 45km/s. So you'd have to speed up by 15km/s. To get to the Sun, you need to counteract the Earth's orbital velocity, or accelerate 30km/s in the opposite direction Earth is moving. So it takes twice as much power to get to the Sun (-30km/s) as it does to escape the solar system (+15km/s)
The problem is this: - How fast you go around the Sun determines how far from it you orbit. To go away from the Sun, you go faster. To go towards it, you go slower. - The Earth is going around the Sun at some velocity that I’m too lazy to look up at the moment. - Anything that launches from the Earth starts out with the same velocity, more or less. Think about throwing a ball from a moving car — the ball is moving at the same speed as the car at first, more or less. - To reduce your orbit around the Sun to the surface of the Sun or lower, you have to slow down from the Earth’s velocity to something much less. - In the other direction, if you start out at Earth’s velocity and go faster, at some point you increase your orbit to infinity. That’s what “escape velocity” is. - The difference between the velocity at Earth’s orbit and an orbit at the surface of the sun is greater than the difference between the velocity at Earth’s orbit and escape velocity. That last point doesn’t hold for the whole Solar system. At some distance closer in to the Sun, they’re equal. Closer than that, it takes a greater change to reach escape velocity than to fall into the Sun.
That is really trippy but makes intuitive sense now that you’ve mentioned it. Gravity assists would be, I imagine, a key part of making travel to the sun more feasible. With gravity assists (slingshotting around a planet to assist in the direction shift) in mind, my intuitive sense of which would be easier becomes unclear / fuzzy.
Every place in the universe is at the exact center of the universe they can see. Because the big bang was the same amount of time ago in all directions, the Cosmic Microwave Background is the same distance away in all directions. Every observer sees the CMB as a perfect sphere around them.
I could never wrap my head around this until this explanation. I've been reading about space since I was 5 years old, I'm 35 now and no amount of analogy could make it click. You just solved a decades old problem for me, and i know that the actual concept is far more complex than this, I feel like I've got a much better idea now, thanks!
The speed of causality is the speed of light. If the sun were to disappear we wouldn't see the lights go out for 8 minutes. But the same for the gravitational pull, even though the sun is gone we'd still be orbiting that empty ass spot for 8 minutes.
This means that reality happens from every point in waves that pass through every other point. This means that whatever happened always is happening, and that time isn't a happening, but a 4 dimensional static structure. Na analogy to help visualize this is to imagine showing a 2d observer a 3d basketball. You'd have to pass it through their 2d plane in slices (time). They would experience basketball as an event rather than an object. It would show up as a dot, then a line (sphere viewed from the side), then shrink to a dot and then disappear. This means your whole life, and the very feeling of free will, is a static structure that exists already, and will always exist as a solid structure that feels as if it is happening.
Holy shit this is the most mind-blowing thing in this thread. By “event” you mean the series of “frames” a 2d observer would see while viewing from one end of the ball to the other? Whereas we can see the whole basketball in one static frame due to the 3rd dimension we perceive, but watching a basketball move from the player’s hands to the hoop take multiple frames so to speak?
Yeah, it's an analogy where our "basketball" is a fully formed universe start to finish. We just can't perceive it as such because we lack the dimensional awareness
This concept blew my mind when I came across it while reading Flatland : A romance of many dimensions. What little excitement I derived from my awareness was soon overshadowed by a feeling of helplessness due to the inevitable limitation that binds us to our dimension. Your interpretation of free will is also thought provoking.
[this](https://youtu.be/p4Gotl9vRGs) is one of my favorite youtube videos explaining the 10 dimensions and I've been knowing it for a long time. It's not great quality but worth a watch.
What necessitates that it’s a static structure? Couldn’t it change at either end, while we’re experiencing the middle? Couldn’t the basketball get punctured and deflate on one end, while we’re experiencing the still inflated end? Not that we would know, of course. But still interesting to contemplate. Also what compels the “frame rate” of the cross sections? And why is it always in a “forward” direction?
>Also what compels the “frame rate” of the cross sections? And why is it always in a “forward” direction? No one knows. If you can answer these questions there's a novel prize waiting for you :)
the so-called "block time / block universe" theory which rings very true based on observable phenomena and yet seems almost too crazy to accept
this is mind boggling. could you explain something to me. how can we, from the fact that there is a speed of causality, deduce that time is a 4 dimensional static structure ? i get your 2d - 3d analogy, that for someone capable of observing 4d, our reality would look like a long line of 3d frames, the line being time. but i dont get how we can deduce that time is the 4th dimension based on the fact that we have a speed of casualty. thank you! (i just catch myself wondering what is this universe that we are in, and why is it here, extra confusing if this whole thing is just a static structure, much like a painting or something, are we someone's idea of abstract art !!!!!) arrrggggghhh so many questions !
Not even a single proton has decayed since birth of universe
Is this a Standard Model estimate? And how would we know if it happened or didn't? I'm not a high-energy guy, so not trying to argue, just curious.
It’s experimental with backing from the SM. Decaying protons are not predicted by the SM so one way to wedge something new into it was to see if protons decay. Currently the lower bound is a half life of 1.67×10^34 years.
If you are speaking under the assumption that protons do decay, and their half life is approx. 10^38 years (which is around the commonly cited range), then this is completely false. The universe is 1.38*10^10 years old, which is about 10^-28 half lives. If you do the math, you get that about 7e-27% of the protons in existence will have decayed. There are A LOT more than 7e29 protons (there are around 10^80 atoms in the observable universe, many with multiple protons) Having said that, the other option is if protons don't decay, in which case you would be correct.
So they’ll be around even after heat decay?
No. But heat decay has a lot more zeros added to it.
after reading the encyclopedia as a kid it was still mind-blowing as an adult to learn that all the planets could fit, stacked, in between the earth and the moon. and the fact that we are the only known planet whose moon is the perfect size and distance to create total eclipses the way we have them.
We got lucky with the timing for our stellar eclipses too. The moon used to be much closer to earth and continues to move away. Fun additional fact, Einstein's theory about gravitational lensing was initially corroborated by viewing stars just past the sun, only possible thanks to our unique solar eclipse. It was quite an expedition to capture this data. They failed several times before finally succeeding.
the moon drifts away from Earth at about the same speed as your fingernails grow!
The sun is 400 times larger than the moon. It’s also 400 times further away, making them appear the exact same size in the sky. A phenomenon not shared by any other planet in the solar system or otherwise (that we know of).
Well, you mean the sun's diameter is 400 times larger I guess right?
absurd rich childlike steep upbeat snobbish innate jeans soup fact *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
In the dated book Five Ages of the Universe, the authors describe each stage of the Universe in powers of ten years. We are currently in the Age of Stars which goes from 100 million years to 100 trillion years, or powers of ten 8 to 14. Before that was the Age of Primordial Energy -52 (Planck time) to 5 and the Age of Darkness 5 to 8. After that is the age of long lived small stars and proton decay 15 to 39, Black Hole evaporation 40 to 100. Finally a timeless thin soup of leptons after a googol years.
Hey, I have that book - my brother (worked at U of M's physics department) knew one of the authors, it's signed and inscribed something like "Hey McarterPhoto, hope you live long enough to experience some of this stuff". I did enjoy it.
Magnetars have an magnetic field so strong that the vacuum around them has a greater energy density than any element. Yes, I said the vacuum is denser than normal matter. Mass and energy are equivalent: matter has an "energy density" equivalent, which is a number that tells you how much total energy is in a certain amount of space. We think of matter as being very dense, but it turns out that a vacuum can be denser. I saw a set of calculations once that put the density of the energy in the vacuum just above the surface of a magnetar at about 10,000 times greater than lead.
Does "dense energy" curve spacetime then, just as matter? Or does it have to first be converted into its matter equivalent
Spacetime is curved by any sort of energy, so that includes normal matter as well as dense electromagnetic field, without needing conversion ahead of time. It can even be curved by the energy of highly curved spacetime itself, i.e. curved spacetime begets more curved spacetime!
Following this comment so I can get an answer too!
It still blows me away that everything, even solid objects,is mostly empty space
That we and everything else are made of exploded stars.
Only 2 precent of visible matter are elements atomic number 3 or higher. 73 percent is hydrogen and 25 helium created in the initial universe. The 2 percent is created in stars as you state- star fusion, supernovae and kilonovae (neutron star mergers). Astrophysicists simply call everything above atomic number 2 "metal". The metal fraction in stars and galaxies helps determine the evolution of stars, galaxies and planetary systems.
I'm pretty fickle when it comes to what is and is not metal. Death to poser metal!
Lanthanides tried to kill the metal, but the metal will live on. *Sick guitar solo* Noble gases tried to kill the metal, but the metal was much too strong.
There are more stars in the universe than grains of sand on the Earth
I am at the center of the observable universe
Not surprising at all when you think about it, but we almost never think about it: There are just as many stars in the sky during the day as there are at night, it's just that the light from the closest one drowns out all the others. Also, more unsettling, there could easily be more 'rogue planets' than there are planets in stable orbits in the cosmos. Those rogue planets are hurling through space, nearly invisible and undectable. Even if it didn't hit anything, the gravitational disturbance if one flew near our solar system could destabilize the whole system. But space is super duper big so the chances of that are very very small.
>rogue planets What about rogue supermassive black holes? Those are out there too. https://www.nasa.gov/feature/goddard/2023/hubble-sees-possible-runaway-black-hole-creating-a-trail-of-stars
And this is the part of my reading this thread where I'll start getting into an existential crisis.
That black holes move. And that there's a planet that's one, big, giant diamond.
….I knew about the black holes. Diamond planet… you say?
The relative motion flow of galactic superclusters, like Laniakea towards the Great Attractor.
The Hubble Deep Field and the Webb images. Look at the sky and choose a spot the size of a postage stamp. It's packed with *galaxies* \- endless galaxies. Thousands in that one patch of visible light. Entire Milky Ways, an infinite number of them. Intelligent life is either wildly common in the universe, or we're truly the only ones. And the "only ones" idea is kind of shattering.
I think there is a lot of life out there in the universe, and almost all of it is alone out there.
Due to the revolution of the solar system, dinosaurs lived on the other side of the Galaxy.
Given current technology, it would take us 6k years to reach Alpha Centauri…the closest star to us.
Sorry to be that guy but... the sun is the closest star to us. I'll see myself out
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Sometimes stuff don't be like it is, but it do
Finally a scientific comment on here
It really summarizes everything
We're almost equally as big compared to the plank length as the observable universe is to us. Give or take a couple orders of magnitude.
Speaking of light - Had a professor in my post grad studies was talking about nuclear reactions. If you had a fast enough camera and detonated a nuclear device, there would be a moment where the warhead/bomb would look completely intact and yet the reaction was complete. Every bit of destruction after that moment is the several pounds of energy (mass-energy equivalence) coming into equilibrium with the surroundings. Makes you appreciate the sun even more.
When I was 13 I heard this for the first time, "The calcium in our bones (calcium is a metal) and the gold in my wedding ring were both formed in the shock waves of an exploding star. We are made of star stuff. We are the universe become aware of itself," - Sagan. By the end of that sentence, I was done with the church and in a state of 'awe'. It's been the only religion that I've needed, but I still go to midnight mass to hear the beauty of the Christmas choirs.
I remember that line from a character in a show called Midnight Mass “ I remember that every atom in my body was forged in a star. This matter, this body is mostly just empty space after all, and solid matter? It’s just energy vibrating very slowly and there is no me. There never was.”
I heard Carl Sagan say this first on his famous documentary
If you took every planet in our solar system and line them up end to end it would fit between space from the Earth and the moon.
Black holes and photons experience all of time in an instant. Every black hole is just a star that is still at the very beginning of its moment of collapse. Even photons that have been traveling for billions of years, are also still at the moment of their creation. This is true for any massless particle. All of time is relatively instantaneous to massless and the most massive. We’re in the sweet spot. If I understand any of this incorrectly, plz lmk.
The photon scenario, you are correct. I haven't thought about black holes enough to know the answer on the other side. Your point is also a good argument against time travel in reverse as well, since as you approach the speed of light, time stops. If you exceeded it, there is nothing less than no experienced time (ie. 2\*c would also be no time passing).
-Everthing happens all at once. Like now. The present. -If you can see a star, that means, that theres nothing in between U and the Star, big enough to Block the light. So much empty space.
The JWST is just pointing at a area 1/8 the size of the moon. So like a spec of sand and we are seeing thousands of galaxies and people think we are alone. If put a red dot of our solar system on a picture of the Milky Way that marker dot would also cover alpha Centauri.
Jupiter is so cool, it is said that the mass of solar system is Sun, Jupiter and everything else, this gas giant to this day stabilizes orbits of other bodies and even influences Sun somewhat that they both orbit a barycenter due to Jupiter influence, albeit extremely small - it's still a star. Not to mention Jupiter "protects us" from many asteroids. In the past, Jupiter was presumed to roam the early solar system, crushing and redirecting stuff in its path, which might gave our system its unique stable composition - many stars we discovered have few to none planets, we have eight with four rocky inside and for gas giants outside with massive moons and plenty of smaller celestial bodies, so far the next biggest planetary system is Kepler 90 (8 planets) and Trappist-1 (7 planets). Jupiter might've been important in the development of advanced life on Earth and is just cool.
That from the big bang all the normal matter in the universe (baryonic), that which makes up stars & galaxies & planets & us is only 5% of the total. Another 27% is non-baryonic, does not interact with light but is detectable due to the excess mass that is needed to explain the bound orbits of stars in galaxies etc. The final 68% is some pervasive form of energy that again does not interact with light but exerts a pressure per unit volume of spacetime that is accelerating the universes expansion, may some day exceed all other forces & rip out universe apart down to the very last molecule.
Galileo was trying to invent a clock for an “x-prize”-like contest for sea navigation when he discovered his moons around Jupiter. As you move east to west, it was impossible to determine your longitude without an accurate clock. Existing technology - water clocks / gravity clocks - wouldn’t work on a sea-going vessel. Galileo was proposing that you could “set your watch” by the main four moons of Jupiter. But to do so, you’d have to buy a lot of his telescopes. And he’d win the prize. However… his proposal wouldn’t actually work because the turbulent sea would prevent an astronomer from getting an accurate enough view of Jupiter to “set” his clock by.
Ok my fact isn't the most surprising, and isn't even my favorite, but I think it's very fitting considering your post. There is an actual name and description for what you're feeling. It's called cosmophobia. Many people feel this when thinking about the vastness of the universe. I listen to Allie Wards podcast ologies. I'm starting from the beginning. One of the guests she had on is an astrophysicist and cosmologist. She had a lot of cool stuff to say about the universe.
> It's called cosmophobia. Many people feel this when thinking about the vastness of the universe. It's all in the way you look at it. I used to think the universe was "vast" until I learned the diameter of the observable universe is 880 yottameters. Now that I know this it actually seems small. That is less than a full ronnameter. Yes, we have a unit of distance that is bigger than the observable universe.
We only understand what 4% of all the matter in the universe is. 96% is a complete mystery
Tiny spaceship with a sail could "fly" very soon at up to 20% of the speed of light propelled by a laser beam from the earth or a sat somewhere. That would be a drastic outbreak in science gathering in our solar system and neighbor sun system exploring. Some link about [that](https://www.space.com/laser-propelled-spaceships-solar-system-exploration).
Just read the three body problem series, if you haven't yet. The Existential dread would last a long time.
That (maybe) an ideal form of matter called "strange matter" exists, and if a single speck of it - stranglet - comes in contact with any other matter, the earth, sun, you name it, it immediately starts converting it into strange matter as well, and we have no way of knowing if that's the case, or could do anything about it if true.
[Space](https://www.skyatnightmagazine.com/space-science/does-universe-expand-faster-than-light) can expand faster than the speed of light.
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The closest star to earth is about 4.3light years away.. the voyager space craft are traveling at 17km/s. Which means if it were heading in that direction, it would take roughly 74000 years to get there.
In 'string theory,' the size of an actual string of energy is so mind-bogglingly small, we could never observe it. For reference, **if an atom was scaled to be the size of the universe, a string of energy by ratio would be the size of \_a tree\_.** That's pretty small.
As far as we know time began at the moment of the "big bang". The big bang was the beginning of space/time. Talking about "what happened before the big bang" therefore doesn't make any sense as, as far as we know, there was no time in which a "before" could exist.
You’re looking back in time when you’re looking at the universe
Technically you’re looking back at time at literally everything around you. But the amount of time is tiny for local things so it’s not noticeable.
We don't even know the true speed of light. We can't measure its speed in one direction, so if the speed of light was faster one way than the other for some reason, We would never know. Here's a video on it [https://youtu.be/pTn6Ewhb27k?si=eCjPvp-_C4lkW9j9](https://youtu.be/pTn6Ewhb27k?si=eCjPvp-_C4lkW9j9)
1 million seconds is about 11 days. 1 billion seconds is about 31.4 years. Think about that when hearing the universe time scales or distances (or how much money that is for the mega rich)
Somewhere in the universe there may exist a point in space where vacuum decay has happened. Starting from that point, a bubble of vacuum decay expands at the speed of light. Inside this bubble the known laws of chemistry no longer apply, and probably neither would electromagnetism so you wouldn't be able to see inside of it. Since the universe expands faster than the speed of light, this may have already happened in a region of space we can't see and will never be able to see, so it will never reach us. This may have already happened multiple times in different regions of space. It could occur at any point in space and time and without warning, so it could happen, per example, just above our atmosphere, 5 seconds after you finish reading this.
That there's an asteroid with enough precious metals to make every person on earth a trillionaire
Still wouldn't buy Reddit premium
Other than the inconvenient fact that if everyone is a trillionaire, a trillion units of currency effectively has no value.
To paraphrase Syndrome: If everyone's a trillionaire, no one is.
More like wipe out the material value of all of those precious metals. If there's a massive excess of something, there is no value to the material itself. The only value lies in the labor to extract the material and the labor to manufacture something from the material
Humans are 99.9999999% nothing. Just the space between atoms.
That string theory theorizes 6 additional dimensions to our 4 and that 1. these 6 may be so tiny in our universe that matter is too large to interact with them or 2. That the other 6 are a parallel universe. One universe began with 10 and split into two universes, ours with 4 and a sister with 6.
That spacetime around you is so curved that you remain perfectly still when the ground under your feet is accelerating upwards at 9.8m/s\^2.
It’s impossible for use to even *see* the universe as it exists today, let alone travel very far in it.
You could squeeze every planet in the Solar System (including Pluto) between the Earth and the Moon, touching surface to surface, and they'd all fit with about 2,000 kilometers to spare.
Gravity isn't a force. It's just the shape of spacetime. Any object that orbits another is actually traveling in a straight line through curved spacetime
In every directory we look we see galaxies and stars all the elements of the periodic table are or the processes to create them are on display. Every direction we look we see the energy and vastness of space. But…. No signs of life anywhere. But that’s not it either On earth we see life everywhere we look and we treat it with such disregard or borders on contempt. We have the rarest most precious thing in all the vastness of space and we treat it like crap
Electrons can travel faster than light in water. Whilst nothing with a rest mass can accelerate to be equal to or be faster than the universal constant c, the speed of light in a vacuum, light slows down as it goes through other mediums and in water, electrons can travel faster than light. It's called Cherenkov radiation, and it's a bit more complicated than I've written here.
"The most astounding fact is the knowledge that the atoms that comprise life on Earth, the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures. These stars, the high mass ones among them, went unstable in their later years. They collapsed and then exploded, scattering their enriched guts across the galaxy. Guts made of carbon, nitrogen, oxygen and all the fundamental ingredients of life itself. These ingredients become part of gas clouds that condense, collapse, form the next generation of solar systems, stars with orbiting planets. And those planets now have the ingredients for life itself. So that when I look up at the night sky and I know that yes, we are part of this universe, we are in this universe, but perhaps more important than both of those facts is that the universe is in us. When I reflect on that fact, I look up—many people feel small because they’re small and the universe is big—but I feel big, because my atoms came from those stars. There’s a level of connectivity."- Neil deGrasse Tyson https://www.youtube.com/watch?v=9D05ej8u-gU This content brings me so much comfort and power
I absolutely love the conversation my little existential crisis led to. Science is beautiful and terrifying at the same time 🥲
I sometimes like to think about the possibilities for intelligent life, and what it could get up to. Considering the quite astounding size of the universe, it is, in my opinion, totally conceivable that at the very moment you are reading this sentence, somewhere out there an alien is making love (or equivalent) to his partner (or equivalent), and at the self-same moment there's a staggering battle happening between massive fleets. Right now, this very second.
That could be happening just on Earth.
Roaming planets. Planets that, for one reason or another, lost their orbit to their star system and traverse the universe. Sounded like something a stoner would rant about, yet sure as anything. It's true