Stamets
MemesQuantum 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.
I don't think it is
It actually is.
Distance itself is expanding in the universe. Like two dots on an expanding balloon doesn't mean there's less balloon, its just the distance itself that expanded.
And the further something is away from you, the more distanve there is to expand. Meaning it moves faster the farther away it is.
What can not travel faster than the speed of light is 'information'. So we have to wait even longer for light and information about a distant object to get here.
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.
This is a truly great explanation. One worthy of Feynman. Physics degree?
All we are going to die?
Yes
Thanks for that that's actually a really helpful analogy.
I mean i still dont understand. Brain hurty. But thanks anyway
courtney you are going to invent rocket ants knock it off
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.
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.
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.
Well, the thing space is moving into and across. Or the nothing.
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
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..
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.
Since nothing can move faster than the speed of light doesn't it also mean that the universe cannot be expanding faster than 2e 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.
Fuck it, question that I had since 10 years old.
if I have a very long stick, and I flick it. what would happen to the tip? what if a laser pointer is used? at a certain distance, the beam would be moving (sideways) faster than light.
it might work better with a whip rather than a solid stick.
The tip of the very long stick would still move at sub light speeds. Also, the atoms at the far end will not immediately know what your hand is doing at the other. The forces the atoms make on each other also travel at (sub) light speed.
The end of the stick would respond at the speed of sound travelling through the medium of a stick.
As for the laser pointer, the thing that’s moving faster than light isn’t really a moving thing any more than something appearing in a 24fps film is moving, if you know what I mean? It’s just an abstract notion of a moving dot. The light that comes back to you from above isn’t the same light that’s come back to you from below.
but how will it look like?
for a short scale it'll be a straight line. but a few light years away? where the abstract dot is moving faster than the speed of light? what shape would you see? definitely not a straight line. and definitely some time issues. like it'll hit you and then you'll see it hit other planets you're left and right?
Think of it like a hosepipe. You’re on the lawn with s long stream of water coming out of the hose. If you flick it quickly it doesn’t stay in a straight line. The beam of water curves as you move.
Because the beam of water isn’t an object. It’s a stream of particles which are constantly being emitted from the tip of the hose
Same thing with a laser beam. It’s a stream of photons being emitted from the laser. If you flick the laser, the photons which have already been emitted will continue in a straight line. Any which are emitted during the flick will head off in a straight line in the direction the laser was pointed. End result:a curved beam
Now I wish I had a nice big wall about a light second away and a massive laser to draw things on it.
Bonus: angle the wall so that the left side is a light second and the right side is a light minute away. Alternate the laser on/off.
Good news! We do have a nice big wall about a light second away! Hard to find a laser that'll make a visible dot on the moon, though
The Information that the stick has begun to move takes time to travel through the stick. Kind of like bending, but not really.
First question: two reasons that wouldn't work: the stick would just break, obviously, but if it was a super duper stick, the torque required to accelerate the end past the speed of light is directly related to how long the stick is, so any increase in speed from a longer stick will be offset by the need to apply more force at your end. Therefore the energy required to flick a stick to the speed of light does not depend on the length of the stick, you are simply creating a reverse lever of sorts. It's still an infinite energy requirement, assuming the stick has mass.
The second question is a lot easier. The light is traveling directly away from you at all times, there is no sideways motion.
It's actually simpler: the stick will deform because whatever movement you do travels across the stick at the speed of sound of the material the stick is made out of.
Why does it matter how long it takes for the torque to travel down the stick? The question was about the speed of the tip in the orbital direction, not the speed of the wave in the radial direction outward.
I see your point. Still, it shows there's no such thing as a "super duper stick" because there'd be shearing forces pulling the atoms apart faster than they can move together.
Yeah that's the boring answer, it would just break apart. But even without physical limitations, mass has the property that it can't be accelerared past c with a finite amount of energy, and I think it's interesting to see why that limit is more fundamental than the structure of matter. No matter how you mess with forces using simple machines, the energy calculations always come out the same.
That’s where things get weird. The tip won’t exceed the speed of light. You could have a section near you moving at the speed of light and the tip will also be moving at c, because c is the limit.
If you were on a train moving at 100mph, and threw a baseball at 50mph in the direction of travel, then the baseball is moving at 150mph. But if you were moving at c and threw that baseball it would not go faster than c.
In fact, everything would move very very rapidly away from the baseball hitting the first air molecule it touches (assuming you yourself have no mass in this scenario).
That's so no matter how much knowledge we gain we can never escape the bad place to kill the Demiurge.
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!
You still have one speed of light, that's the Lorentz transformation
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.
A shadow can move faster than light too.
A shadow never actually moves.
you running vs a train vs you running on a train vs measuring two people running away from each other on two trains travelling in opposite directions
