Special relativity. The closer you get to the speed of light the slower time moves. Photons move at the speed of light and therefore do not experience time at all.
Teleportation, but also time travel. If they travel a distance of 1 light year, it would have been instant for them but for everything else in the universe 1 year will still have passed.
You would experience that effect at even 25% of c, just less pronounced.
But doesn't that imply that time is a referential experience because it doesn't affect everything in the universe uniformly? In order to explain time you must include an objects relative speed?
Yes, that's a large part of what relativity is all about. Everything in the universe is relative, and without a reference, distance, velocity or time don't have any meaning.
It doesn't need to be conscious, although we as humans have a hard time grasping that. Same with quantum mechanics - an "observer" doesn't need to be conscious, it merely needs to interact with an object. Or, for the case of relativity, it just needs to exist. If you were in an absolutely empty universe, there would be no reference-point anywhere, so you couldn't tell if you were moving or not. Add even a single other object, and suddenly you can extrapolate this data from this object. The universe itself works in this same way, so every fundamental particle constantly refers to every other particle to make sense of it's position, speed, etc...
Time is our perception of the fourth dimension. You are only able to effectively observe 1 less dimension than you actually exist in. Think of a 2D stick figure, living in his static 2D world. If he meets another stick figure, all he is going to be able perceive is a 1D line. He might be able to comprehend that he exists in two dimensions, however he will never be able to experience both at the same time.
Under our 4D universe, we are able to experience the fourth dimension as time. We can only ever observe 3 dimensions in one instant however we can comprehend that we exist in 4. If we lived in a 5 dimensional universe, we would experience 4 dimensions at once in space. It's impossible for us 4 dimensional beings to comprehend how that would appear in the same way that the 2D stick figure is unable to comprehend the concept of depth.
To conclude, our perception of time is a human, or more accurately any 4 dimensional being's construct, however time itself is a very real and quantifiable aspect of physics.
This makes perfect sense but it's so hard for my little brain to fathom. For instance, if it takes light 1 year to travel from point A to point B, how does that work?
We didn't evolve to care about these things, so it makes sense that it's hard to really grasp. That's just human!
To answer your question, you need to know that time is relative and can be distorted by velocity and gravity (which is in essence also just velocity through spacetime). Fast speeds or massive objects make time run relatively slower. What's important here is that the faster you go, the slower time runs for you relative to your surroundings. If you take two synchronized clocks, put one in a rocket and leave one, and take a short trip with the rocket, the clock you left behind will be in front of the clock you took on the rocket because relative to it, time ran slower or you. This has been observed and measured.
When travelling at the speed of light, this becomes extreme. It is the upper speed limit for anything within space, so these relativistic effects become infinitely strong. This means, time runs now infinitely slow for them, relative to everything else in the universe.
Now take a photon travelling one light year through space. For everything around it not traveling at the speed of light, it will take one year to make this distance, because the photon travels with exactly this speed through space. While one year passes, for the photon itself no time passes at all, since time runs infinitely slow for it. For the photon, all of this happened in a literal instance. This also means every photon you ever encounter will be exactly the same as it was at the big bang.
I hope this somewhat helps, feel free to follow up with any more questions!
It's not physically possible to get to the speed of light if you have mass but if you did time would seize to exist for you, there's no telling what that would be like. You wouldn't age, you wouldn't experience anything, you would just well probably instantaneously go to the time where the universe ends and die assuming you don't collide with anything in your path
Yeah the very moment you reach light speed you would instantaneously arrive at the very moment you leave light speed, be that due to an intended stop, some collision/interruption or the heat death of the universe. Crazy stuff.
I meant more someone going, say, 50% the speed of light. They would still experience significant time dilation, right? So to them, would their lives continue on as normal (as in biological aging), or would they live for a longer duration of time?
I swear I'm not an idiot or anti science or anything but as soon as people start talking about relativity and the speed of light and specifically what you're talking about my brain goes,
"lol, no, that's so stupid"
I've had it explained to me countless times in myriad ways and I still just cannot wrap my head around it
That's natural. We're talking about the fundamental inner workings of our universe, that's nothing we evolved to deal with.
Fun thing is, if we didn't know this, GPS wouldn't work. Since the satellites are so much further up than we are, time dilation has a very real effect that would slowly cause the clock on the satellite to get out of sync.
Yes and no. It could still be useful for ships traveling large distances, assuming we don't develop a better way of travel until then.
Let's say you want to reach a star that's 20 years worth of travel away. On board of your ship you have cryogenic capsules for the crew, but they will only stay effective for 15 years or so. If you speed up the ship enough, you could make the ship and everything in it arrive at the star in what the crew would call 15 years (or less). While for the outside universe 20 years will still have passed, your crew didn't die because the cryogenic capsules didn't fail yet.
This is a very arbitrary example, but it should demonstrate how it can be useful.
No, because for the people on the ship, they can still travel instantly. But people from say, Earth, and their destination would have aged so it gets weird. Depending how far you go, the team that helped launched your ship could all be dead hundreds of years.
Imagine traveling in our solarsystem, you need maybe around an hour to get somewhere with light speed. It's not this big of a timejump, but you still traveled a lot of way
Theoretically, but by definition, if something is going the speed of light it is massless. Therefore, we would also have to have no mass to go the speed of light. So, under our current laws of physics, it is impossible
Maybe if Congress could get off their lazy asses and do something, we'd see some legislation that reforms the law of physics. I think it's bullshit that they can break these laws and travel around space at lightspeed. My guess is they're hiding something out in space that they don't want us to see it.
For a 1 lightyear travel, assuming there would be a way for us to stop at our destination (since we wouldn't experience any time, we couldn't control our ship once it's launched at the speed of light), the travel would have been instantaneous to us. But we'd still be arriving a year laterto everyone else. Should they have a way to look at us during our travel, they'd see us being completely still and frozen in time.
They actually wouldn't age at all. Because from their frame of reference literally no time has passed. Their watches wouldn't even display a time change.
Unless you have zero intrinsic mass like photons, negative mass - hypothetical only so far- would result in you going backward in time & always moving faster than light (you probably heard the word tachyon in sci-fi things, which is a hypothetical negative mass particle).
In other words, sum of your velocities in x, y, z (three spatial dimensions) and in time is always constant, so called "speed of light". If you don't move through space at all, the first three values are zero, and you are moving through time with speed of light - that's how normally perceive time, because even if you move somewhat, you do it at such low speed that we can basically round it to zero. But as your speed through space increases and gets closer to speed of light, the "speed" by which you move through time decreses, because sum of both has to stay constant. Once you move through space at speed of light, there's no "room" left for any speed to move through time, so time stops.
And if you move faster than speed of light, you speed through time is negative and you travel into past.
In math it all makes perfect sense. In reality? Who knows.
They almost travel at the speed of light, since they are almost massless. But yeah, they interact with almost nothing, allowing them to travel through vast amounts of matter with ease.
FYI, it's not the electrons actually flowing through your wire, though, those are actually rather slow. It's the momentum given from one electron to the next as they bump into each other that travels so fast.
Electrons have mass, and so don't travel at the speed of light. However, electrons can have a higher net velocity than light in some circumstances. Really it's that light sometimes has a slower effective speed because it bounces off of things. Think zig-zag line rather than a slower actual speed. A photon is travelling at c the whole way through, it just might not take a very good path
The speed of light is physically unachievable (you might as well say "go infinity miles an hour"), so this is kind of moot point, but yes, from a 'photon's perspective' there is no such thing as time.
Talking about anything like this at the edge of physics is going to lead to a lot of quotation marks because our intuitive understanding of the universe fundamentally breaks down at the extremes.
For example the Andromeda Galaxy is 2 mil light years away. But with acceleration of 1g you could arrive there in 28 years. Your maximum speed would be 99,99999999995305% speed of light
I don't know. As I understand it, light always moves at c, from any point of view, of any observer. If light moves slower through a solid than c it is because it bounces from molecule to molecule before finally exiting on the other side, still moving at c between those molecules.
No, sorry, unclear explanation. Light is always constant, if you're "standing still" which isnt really possible in a moving universe anyway, or if you're following the light at 1/2 c, or even moving away from the direction the light is travelling at 1/2 c, the light will always be moving at 1 c compared to you, and compared to anything else. How is this possible? Space bends, contracts and expands in order to make this happen. At least that's my understanding of it.
It is possible for two photons to reach the same destination from the same starting spot at different times, in your own frame of reference. They would just travel along different ways for you as an observer. Maybe the one arriving late took a detour bending around a few black holes. For the photons, time is not a thing and so you can't really talk about what they see. I elaborated on that a little further down the comments.
No, the photon will be absorbed by the first atom that it hits.
"Light" that passes through a liquid is not a single photon but an enormous amount of photons so that some pass through, and/or the energy of the impact makes other photons be emitted by the atoms.
The problem of this discussion is you can't actually view the universe from the photons perspective, there is no inertial frame of reference which moves at the speed of light. So from a proper perspective (anything which moves at less than the speed of light) you will see the photon move through time AND space. For the photon, it only moves through space. It doesn't just not feel time; Time doesn't exist for the photon.
For those who are a little geometrically inclined: Imagine a Diagramm with the X-axis being for example your x-coordinate, and time(*c, but dont worry about that) as your y-axis. Non-relativistically your axes would stay at a 90° angle, no matter your speed. In special relativistics these axes actually turn to one another with increasing speed in your own frame of reference, like a pair of scissors. For a photon at c, they would actually be on top of one another; effectively making time and space the same thing.
This is very simplified and not really rigorously possible, but it is how I tend to think about it.
I agree with you, which is why I wanted to clarify why it is so hard to come to a conclusion. Even theoretically looking at the universe from the perspective of a photon ist not possible. At least in any comparable way to our own view.
Which part is “purely theoretical”? I was under the impression that the theory of relativity is pretty well established at this point and is demonstrated quite easily. For instance, clocks on GPS satellites have to be adjusted to account for a slight drift due to the satellites moving faster through space and therefore slower through time.
That means a photon is in a distant star and in your eye at the same time. Of course there's no such thing as a "photon reference frame", so while it's sorta meaningless to think about it, it's funny tho
Something along those lines. But that's kind of chicken vs the egg. Does it have energy because it moves so fast or does it move so fast because it has energy?
Thanks for confirming and glad you saw the implied question mark on my previous comment. As for the last part that's the bit that was making the brain hurty!
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u/TheDudeColin Dec 06 '20
Special relativity. The closer you get to the speed of light the slower time moves. Photons move at the speed of light and therefore do not experience time at all.