The universe is mostly nothing. So obviously the universe, being nothing, expanding faster than the speed of light isn’t surprising, as nothing is faster than light. 😌
besides the expansion of spacetime which is the correct answer, there’s also nothing keeping two objects from traveling in opposite vectors each at 60% c. Frame of reference matters too
Explanations why space expands are way more crazier than this.
Wrong, the expansion doesn’t have a speed because it isn’t motion. But you have to think about it longer than you’ll probably want to before hitting the up or down arrow and/or scrolling.
Best intuition I’ve heard for this is that “things” can’t move faster than light, but not everything is a “thing”.
Imagine doing shadow puppets on the wall with a flashlight. You move the bunny left, shadow moves left. The further away the wall is, the faster the apparent speed of the shadow bunny. You might think that, far enough away and with a strong enough light, your shadow bunny would be racing across the sky faster than the speed of light – and the crazy thing is, you’d be correct! The shadow (absence of light) can move arbitrarily fast. But the light itself is moving at its normal constant speed from the flashlight out into space, perpendicular to the travel of the bunny, like a garden hose spraying water. The time it takes for the shadow to even begin to move is governed by the speed of light. No information can be communicated faster than light because the light travels at the speed of light to illuminate the places where the shadow isn’t.
Very eloquent explanation. The one glitch I must point out is that the shadow (or absence of light) can’t move faster than light, because the shadow is information and information can’t travel faster than light. If it could, you could use a sequence of shadows, coded by length and spacing, for FTL communication.
The shadow has no FTL information here. Watch https://youtu.be/JTvcpdfGUtQ
The shadow moving is more akin to bandwidth of transmission rather than speed of transmission. You still have to wait for the photons (so speed of light) for the information to arrive, even if the “speed” of the shadow appears FTL.
Best analogy I heard for it is if you put a load of dots on a balloon, then inflate it. Are the dots getting further away? Yes. Is there just the same amount of rubber between each dot as when you put the dots on? Yes. Can you measure the relative speed of the dots? Yes! But have they actually gone anywhere? No…ish?
Yeah, but in this case is the universe just the dots on the surface of the balloon or is it the whole balloon with its entire volume? Intuitively I think it’s the latter (although there’s probably no “hard” edge that’s bounding the ends of the universe like the rubber of the balloon), and if that’s true, you could measure the speed of one wall getting away from the centre or the speed of two opposite walls getting away from each other.
I could be wrong of course, I’d be happy if someone points out what I might be missing.
No, you completely understand quantum physics, you are one of the elite.
But in the analogy I don’t think we know what the air in the balloon is, we call it expansion. But I don’t know enough to say anymore
We are the dots on the surface of the balloon. Things really far away seem to be moving away from us. Hopefully we can figure out what gravity is because that would have a lot of gravitas I dunno whatever
I’m fairly certain that in the balloon example metaphor, we are two dimensional creatures on the surface of the balloon
Space time itself is expanding which means I will now blow up soon. Yay!
Yeah, when you put the dimensions implication in it it starts making a bit more sense - implying that we’re two-dimensional and the third dimension inside the balloon is the things that we don’t fully comprehend (yet).
Yep I think you have to imagine dots suspended in space inside the balloon to better get what’s going on, and you’re right, the “edge” of the universe is definitely nothing like the surface if the balloon. Probably?
Great analogy, and yeah the “ish” is the fun part!
The fun of justifying a reference frame outside the universe. Sorry I’m getting a headache.
You can explain but don’t but criticize you are idoltarer and are in degenerate dharma like all Christians nowadays
Nothing within the known universe moves faster then light, but the universe itself expands faster then light travels within it.
Preemptive explanatory note: the speed of light, approximately 300,000 km per second, is the highest speed that something can move through space.
The expansion of space doesn’t happen at a set speed. It happens at a rate of approximately 70 km per second per megaparsec. So if you’re measuring two points half a megaparsec away from each other, then every second, the space between them grows by about 35 km. If you’re measuring two points 2 megaparsecs away from each other, then every second, the space between them grows by about 140 km.
If you’re measuring two points 4300 megaparsecs away from each other, then the spacetime between them grows by about 300,000 km every second. That’s not to say that anything is moving at 300,000 km per second, there’s just more space between them every second
just more space between
Space out of thin air… tell me, mate, can I sell it?
NFT’s sold, so probably yes
Wtf is a megaparsec? It’s a million parsecs. Tf is a parsec? A parallax arcsecond.
…Tf is a parallax arcsecond?
An attempt at an explanation for the layperson
Imagine you’re standing outside. In front of you is a tree and behind that on the horizon is a mountain. You move 10 ft to your left, and the tree looks like it moved to the right, but the mountain looks like it hasn’t moved at all. That’s parallax. The closer something is, the more it appears to move when you move.
Imagine you are the pivot point on a big protractor. Your field of view can be divided into 360°. Every degree can be divided into 60 parts, called arcminutes. Every arcminute can be further divided into 60 arcseconds. Each arcsecond is 1/3600 of a degree.
How do these fit together? There’s one more thing I need to explain.
The earth orbits the sun at around 149.6 million kilometers. That’s called an Astronomical Unit. A parsec is the distance that an object would have to be, so that moving one Astronomical Unit would make it appear to shift sideways by 1 arcsecond.
Fraser Cain did a better job explaining, because he can use pictures
It’s 3.26 lightyears.
Beautiful! That’s the kind of perfect explanation I was trying to come up before giving up and just saying the expansion doesn’t have a speed because it isn’t motion, which is only partially correct lol.
This guy expands!
Take a balloon.
Blow it upto about 50mm
Make a couple dots around it
Blow it up a little more.
Now there’s distance between the dots.
Imagine an ant walking between the dots. That ant is going at the speed of light (as fast as it can go) relative to the dots.
Now as it walks between the dots, blow the balloon up really big
The dots aren’t moving, they’re stuck to the surface of the balloon. The balloon itself is expanding. The ant is going at the speed of ant-light, but now the dots are all “moving away” faster than the ant can walk.
The speed of the ant hasn’t changed, the space the ant is traveling has changed. And faster than the ant can move, because the balloon isn’t limited by the same things the ant is.
Didn’t get it but saving this so when i grow older I’ll see it again and think for the logic behind it… 🗿
deleted by creator
All we are going to die?
Eventually, the universe itself will “die” when it hits absolute zero and nothing moves anymore. Nothing can happen after the heat death of the universe (unless protons decay)
Finally, some good news.
https://en.wikipedia.org/wiki/Timeline_of_the_far_future breaks this down.
Current data suggest that the universe has a flat geometry
Holyshitholyshitholyshit don’t tell flat earthers
Yes
Not unless you donate some seed money to my church. It will come back to you, and then you pay twice as much and then I pay half. And then you, a vulnerable population, gain faith in the process and give more and more and I give less and less but this is just friendly educational propaganda from your friendly neighborhood juggler and CIA spook.
Yes, and actually right now relatively speaking.
Thanks for that that’s actually a really helpful analogy.
I mean i still dont understand. Brain hurty. But thanks anyway
This is a truly great explanation. One worthy of Feynman. Physics degree?
Lmao no, just autistic fascination with space and many thousands of hours of listening to astrophysics lectures and hundreds of hours listening to edu-tainment type videos from people like Dr. Becky Smethurst.
Thanks for the compliment though, I’ve heard the balloon explanation since I was a child, but the ant-splanation of light speed just popped into my head.
The space between atoms starts to expand faster than the speed of light. Well i guess that is the universe fucked.
Good thing the atoms (and the subatomic particles) are pulled back together as the universe expands. The same way we are pulled to Earth by gravity and don’t fly off into space as the universe expands.
This does, however, lead to the existence of “local groups”.
Meaning that, there is a local group of celestial bodies that we may theoretically be able to visit at some time in the future, which are held somewhat together by gravitational forces which help to counteract the expansion of space. But anything outside of that local group will be expanding away from the group at greater than the speed of light.
Meaning, effectively, that the universe is going to be / is already separated out into small pockets of local neighbors, who will never be able to reach other local groups unless they invent some sort of much faster than light travel. The universe is very, very large, but the percentage of the universe that is physically reachable by us is quite small, no matter how many generations we spend on the journey.
Personally I find that to be one of the more disappointing true facts about the universe.
Exactly, there will be causally disconnected pocket universes in the future. I’m thankful we still live in a time when we can see the rest of the universe. Creatures alive in 100 billion years might have no way to figure out how the universe started, or that there is anything outside of their local cluster at all.
I’m thankful we still live in a time when we can see the rest of the universe.
Do we though? How do you know our entire known universe isn’t just a local cluster?
If we could see the entire universe, then somewhere in the center we’d be able to point to the origin of the Big Bang. Since we can’t, that implies we’re only looking at a section of the universe analogous to a portion of the surface of a globe.
Someone else already replied probably better than I can, but this is one of my favorite subjects to study.
The big bang didn’t really start in a place, it happened at a point in time. As we look at all of the galaxies around us (minus the close ones we are gravitationally interacting with) they are all moving away from us, so either 1) we are exactly where the big bang took place (vanishingly unlikely) or 2) the big bang happened everywhere and all of space is expanding from that event.
We can actually see the first light ever released in the universe (not from the big bang, as the universe was a dense plasma for the first ~400,000 years until the recombination era) as the cosmic microwave background radiation. And it is (relatively) even in all directions, minus some minor temperature variations.
I highly suggest looking at a channel on YouTube called PBS Spacetime. They have videos going back years and years that dive into great depth on all of these topics!
Yes, I already responded to the other comment. Summarily, I don’t find their argument convincing.
To add, it’s not surprising that everything is moving away from us. To use the other commenter’s balloon analogy, as the balloon expands, so do the circumference and surface area. So any two points on that surface will be moving away from each other as it does so.
It’s also not surprising that the cosmic microwave background radiation appears relatively uniform. 14 billion years of expansion, and we can only observe or “neighborhood” of the universe, mind-bogglingly large as even that is. 14 billion years of moving on a more or less stable trajectory. We can’t see far enough backwards to view the origin point.
Also, if the background radiation came from the big bang, then it would have outpaced us as our galaxy slowed down and the radiation continued moving at the speed of light. This suggests that the background radiation we witness was emitted after the energy that coalesced into our galaxy, and is just now catching up/surpassing us. Unless it’s reflecting off of something further outward, and on it’s way back.
Is there any known pattern to the actual direction of cosmic background radiation? Is it aligned in any way or more or less random?
By the nature of the Big Bang and the expansion of the universe, everywhere is at the origin. That is, if we believe that the universe started out as a singularity, and that the expansion of space itself is what causes that singularity to grow, then every point in the universe originated from the exact same point, and that nothing has “moved”, in the sense that the point itself is expanding. Thus, every place is at the “origin”.
To use the balloon analogy: Draw a small dot on the balloon, that dot is the entire universe as a singularity. Now, inflate the balloon so the dot grows, and try to determine the “origin” of the dot. Of course, you could point to the centre of the dot, but I would argue that if the initial dot is infinitely small (a singularity) then every point on the expanded dot in fact originates from the exact same point.
This does cause a bit of a headache because we’re arguing that a zero-dimensional thing suddenly became 3-dimensional. I’m honestly not sure how astrophysicists reconcile that, but I seem to remember reading that they boil down to saying “we know what happened <some extremely short time> after the Big Bang, but we don’t really know anything about what happened at t=0” per my understanding, even the concept of time breaks down when you go to t=0, so it becomes impossible to get to t = 0 + h.
That doesn’t make any sense, down to the geometric level.
By the nature of expansion itself, there is an origin point somewhere in the center. That holds especially true in the case of uniform expansion.
If “every point in the universe originated from the exact same point” then that origin point is somewhere in the center of the universe, and tracing the trajectories of every point backwards should intersect somewhere very close to that point.
Your balloon analogy supports this thesis. No matter how much the dot expands, the center of the dot is where it originated. Yes, every point on the expanded dot originates from the same point. That point is in the center.
Saying “sometimes physics is mindboggling” in order to rationalize invalid leaps is not a strong argument. Yes, sometimes physics is mindboggling. But that’s no reason to handwave away inconvenient facts whenever we’re trying to argue for something illogical. You need rigorous evidential support to justify a mindboggling conclusion, as is the case with quantum mechanics. Speculative or theoretical physics however cannot simply fill in the gaps with this sort of handwaving.
Honestly, if the concept of time breaks down when you look at t=0, then that only tells me that the idea of t=0 itself is invalid and needs to be abandoned. Especially since there’s no evidential support for that theory, it’s entirely speculative, and has only been justified with the explanation that “We don’t have any better ideas.”
Time didn’t just magically start at some random point before which time didn’t exist. And space didn’t just magically expand into 3 dimensions before which there was only 0. Energy and matter didn’t just suddenly appear without any prior cause initiating some action. All of those things would require violations of the laws of thermodynamics. And in the absence of far more evidence than ever has or even can be found, this “best guess” is full of more holes than many people seem ready to admit…
How fast space expands is described by general relativity. For the space between atoms to expand faster than the speed of light, you need a shitload of energy crammed together very densely, like a galaxy worth of stuff in every atom. This is called cosmic inflation, and it’s what happened during (and possibly before) the first part of the big bang.
We don’t know exactly how there can be this much energy in this little space, or where it all went, but we do know it was there because there are waves imprinted on the density of the universe.
Without trying to explain things even in not sure I grasp, no. The atomic forces keep atoms together, and expansion of space is only noticeable on long distances. Like light-years and parsecs kind of distances.
Also fun fact: the rate of expansion is not only INCREASING as space expands, last information I saw suggested space is expanding faster in some directions than others, which is fascinating for a number of reasons.
courtney you are going to invent rocket ants knock it off
But space contracts at close to light speed,so your analogy isn’t perfect, right?
No, time contracts, not space.
Well, nothing (with nonnegative mass) can move faster than light through space. Space itself can do whatever it wants to.
I don’t know why maybe the painkillers are speaking but I have to ask, does farts count as negative mass?
I’ll take my leave…
ᕕ(ᐛ)ᕗ
Okay … enjoy your painkillers, man.
Incoming vibe killer: no, farts do not count as negative mass. They do in fact have positive mass. You will weigh ever so slightly less after farting. And, in theory, if you were in a frictionless environment, you could propel yourself by farting, because the fart’s mass would act as a reaction mass and propel you like a (very weak and stinky) rocket.
Negative mass would be a very weird thing that breaks physics in a lot of ways, and probably isn’t physically possible in the first place. Allowing faster-than-light travel is only one of many stupid ways negative mass would horribly wreck all known physics.
Thank you for the explanation.
Well, the thing space is moving into and across. Or the nothing.
How to tell people you don’t know more than school level basic science: the person who made that image and OP making this thread.
All you did was write “hey, I don’t comprehend things that are easily learned and have been freely available to learn from your own home via the Internet for several decades” on a sticky note and put it on yoir forehead, then went into a public place for everyone to see and somehow didn’t realise you did any of that.
my personal headcanon is that the universe is a giant living being and we are its fundamental particles or some other infeasibly tiny thing
idk what that has to do with light speed and space-time but you can think of that yourself i guess
When I was a kid I imagined that our universe and every galaxy in it make up a single atom in another, much larger universe.
That much larger universe, in turn, is also a single atom in a much larger universe. And so on…
Dark Tower did the same bit as well
And Men in Black.
I have had thoughts like that before! Especially since at school the atomic model that was taught looked like a little galaxy (which I now know is inaccurate) and it seemed like going smaller or going bigger just repeated similiar patterns, so to say.
“As above, so below” is a pattern that’s almost universally recognized for a reason. The galaxy atom model may not be accurate, but lots of things in the world rhyme at different scales.
Thank you! I used this weird thought to wipe my brain from other weird thoughts, it needed that.
The speed of dark is faster than the speed of light
Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it.
Terry Pratchett
Quantum entanglement is faster than light
Nope. Quantum entanglement is when two particles are made to have the same states. Measuring one tells you about the other one in much the same way you can tell what someone you’ve never met before looks like if you’ve seen their identical twin. Also, much like how punching one twin in the face and breaking their nose has no effect on the other twin fifty miles away, doing something to one half of an entangled pair does nothing to the other. In fact, because they’re no longer identical, the particles aren’t considered to be entangled anymore.
Entanglement can be used for encryption, but it can’t be used to transmit data.
Nope!
Information can only travel at the speed of light.
During my undergraduate CERN did this experiment (a decade ago now).
And they had the shocking result of the second wave function collapsed faster than c.
That was until a clock was found to be loosley connected and caused a timing error, that would account for the slower than c speed.
Information can only travel at the speed of light.
I like the general term being used nowadays instead of “the speed of light” - the speed of causality; which is nice because it fits neatly into E=mc2.
Well duh. When a thing moves away from another thing, that is moving at the speed of light, at the speed of light, you have speed of light time two!
This explanation is the wrong intuition for why space can expand FtL. It’s an understandable one to infer, but the balloon one further down is correct and the one most commonly used by cosmologists for a lay audience.
Our current understanding of recessional velocity works by Hubble’s law, and that linear equation imposes no such 2x cap.
You still have one speed of light, that’s the Lorentz transformation
That’s so no matter how much knowledge we gain we can never escape the bad place to kill the Demiurge.
Since nothing can move faster than the speed of light doesn’t it also mean that the universe cannot be expanding faster than 2c either?
Not necessarily.
The expansion of the universe here doesn’t necessarily mean matter moving faster than light.
Think of the universe as a 3+1 dimensional ballon - specifically, the 3D space we occupy is the 2D surface of the balloon. As you blow air into the ballon, that 2D space expands.
Now, it’s a simplistic example mainly because we’re three dimensional beings and thus can’t easily wrap our heads around a 4D space where one of the surfaces is three dimensional. You run into the same issue as e.g. trying to visualise a tesseract (a four dimensional cube). So a balloon has to do.
And since this expansion of our universe technically happens outside of it, the general laws of physics - such as the speed of light - do not apply.
That’s what I meant. Since matter isn’t moving at the speed of light, if we assume the universe expansion is due to the movement of its edge objects, then it cannot expand faster than 2c. If the expansion is happening for a different unrelated reason than the edge objects ofc that’s something else
Your presumption that there’s an “edge” is at fault here. Consider the surface of the ballon (or rather- a bubble) - it’s continuous, just like our universe. And that’s why it’s hard to explain how a 3D space can expand seemingly without a center point - because said center point is not within the constraints of this 3 dimensional space, just like how the center of a balloon or bubble is not on the two dimensional surface but in the center.
so just like the surface of an expanding bubble, the expansion of our universe doesn’t happen in a plane we can conceptualise easily - it’s a 4 (or possibly more!) dimensional expansion, of which we are just the surface, therefore the expansion appears as if everything literally drifted away from everything - which should be impossible in a 3D space but not when you add a fourth axis.
I don’t know much about astrophysics, but it seems to me the analogy breaks down. Unlike a balloon, the universe does not move on a medium, so the only way to surmise it’s size is by its edges (i.e. the objects at its farthest edges). So the important thing here is how fast those edges move (the dots, on the balloon) which can never be higher than the speed of light. What am I missing?
