4 ms·

As you approach the speed of light, the amount of time you experience gets slower as compared to a stationary observer. This means that a photon, which travels

As you approach the speed of light, the amount of time you experience gets slower as compared to a stationary observer. This means that a photon, which travels at the speed of light, actually experiences no time at all. I like to think of time and space as two different directions you can go i.e. forward/backward (time) or left/right (space). A stationary observer travels only forward, i.e. through time. So they experience lots of time but very little or no space. As you get closer and closer to the speed of light you're moving less in time and more in space. Your vector gets closer and closer to pointing right (using this analogy). An observer traveling at light speed experiences only space, i.e. no time at all. Then, once you exceed the speed of light your arrow starts pointing a little bit backwards. You're still traveling mostly in space, very little in time but now the time you do travel in is actually negative. I forget where I read this vector explanation but it's one that makes the concept tractable in my mind :)

thatcherc 8y ago
The picture you're talking about is a Minkowski diagram and it's very useful for conceptualizing how time and space change in fast reference frames. [0] [0] - https://en.wikipedia.org/wiki/Minkowski_diagram https://en.wikipedia.org/wiki/Minkowski_diagram
nsxwolf 8y ago
The way I like to think of it, and I'm not sure how valid my thoughts are... I think about what you would experience as an observer in a ship traveling faster and faster. If the ship had a window to look out, you wouldn't really be noticing anything happen to time, you'd be seeing the universe get squished, with everything getting closer and closer to you. If you managed to actually achieve the speed of light, the universe would be completely flat. Everything would be contained in a single plane perpendicular to your direction of travel. So now, what would it mean if you went even faster? The universe would no longer be flat, but would be achieving a negative size. What that really means is not clear to me, but I suppose it's here where the traveling back in time starts to make sense mathematically.
heed 8y ago
I'd like to add that you're always traveling at the speed of light. If stationary you're traveling through time at exactly the speed of light, but as you move through space you start traveling through time more slowly. In other words, the speed at which you travel through time + space is always c.
radarsat1 8y ago
I love this explanation because when I started thinking of it this way it blew my mind in ways that no other physics concept has. It's something that truly sounds crazy except that as far as I know it is a valid interpretation. (Layman here.) We think of time being this thing that just moves forward around us, and we can't stop it, time just goes. But in this interpretation, it's us who are falling through time, literally. I find that fascinating because it changes entirely how I think about the universe. I used to think of the "big bang" as a big explosion of little balls of energy (quarks, electrons, whatever) that eventually coalesced into matter, when enough time had passed and there was enough room for things to cool down. The part that I never understood before this interpretation is how "enough time could pass", when time itself was also supposedly expanding. But in fact with this interpretation, which I guess is probably more correct (?), space and time simply exploded and began expanding.. which is what we're told but it's hard to picture, exactly. But if you think about energy always moving at the speed of light, and initially all of it flying off in the same direction (time), then matter becomes those particles which were somehow slightly diverted onto the spatial axes -- momentum is conserved, just redirected. And if you think about particles being ripples in fields of non-zero constant energy, an interactions between the fields causing ripples to bump away from each other in non-time directions which we describe as space, this whole relativity thing, and the fact that electric field particles (photons) do not have mass and move at c, starts to make a bit of sense. It's crazy to think that what we perceive as time passing, the very possibility of things happening, is actually an emergent property of simple geometry and interactions of pure energy. The way I visualize it is: start two marbles rolling towards each other down an inclined slope. They bump, and bounce off in opposite directions on the X axis. Now imagine there is no table. Would the marbles "feel" anything in the vertical direction? Or would they only feel something in the horizontal direction? Time, for them, emerges from the fact that they can get closer, bump, and move off in the other direction. The other axis, which they are both moving very quickly in, they have entirely in common and they might agree with each other that it is simply a stationary frame which allowed the "bump" to happen. Same for us falling, unrelentingly and unstoppably, through time. (Maybe?)
- TeMPOraL 8y ago
  Except mass/energy must be really drawing a line across time dimension, instead of being points in it, right? Otherwise anything traveling in space - and thus slightly sideways - would immediately desync with the universe around it and interact only with emptiness?
dreamcompiler 8y ago
> This means that a photon, which travels at the speed of light, actually experiences no time at all. Yep. If a photon could talk, it might say "What is this 'time' thing you speak of?" And since time has no meaning, neither does 'traveling'. A photon is always 'everywhere it's ever been or ever will be' so it might also say "What is this 'space' thing you speak of?"
foobar1962 8y ago
>As you approach the speed of light, the amount of time you experience gets slower as compared to a stationary observer. My impression was that the wormhole was used as a "shortcut" between two distant places to avoid having to travel very fast. Imagine a race where everybody else runs the whole course but you take shortcut. You haven't physically travelled fast but your path has been shorter. I'd guess that Big Banking is blocking the development of this, it'd be a nightmare for inter-galactic ATM machines.

thatcherc 8y ago

The picture you're talking about is a Minkowski diagram and it's very useful for conceptualizing how time and space change in fast reference frames. [0] [0] - https://en.wikipedia.org/wiki/Minkowski_diagram https://en.wikipedia.org/wiki/Minkowski_diagram

nsxwolf 8y ago

The way I like to think of it, and I'm not sure how valid my thoughts are... I think about what you would experience as an observer in a ship traveling faster and faster. If the ship had a window to look out, you wouldn't really be noticing anything happen to time, you'd be seeing the universe get squished, with everything getting closer and closer to you. If you managed to actually achieve the speed of light, the universe would be completely flat. Everything would be contained in a single plane perpendicular to your direction of travel. So now, what would it mean if you went even faster? The universe would no longer be flat, but would be achieving a negative size. What that really means is not clear to me, but I suppose it's here where the traveling back in time starts to make sense mathematically.

heed 8y ago

I'd like to add that you're always traveling at the speed of light. If stationary you're traveling through time at exactly the speed of light, but as you move through space you start traveling through time more slowly. In other words, the speed at which you travel through time + space is always c.

radarsat1 8y ago

I love this explanation because when I started thinking of it this way it blew my mind in ways that no other physics concept has. It's something that truly sounds crazy except that as far as I know it is a valid interpretation. (Layman here.) We think of time being this thing that just moves forward around us, and we can't stop it, time just goes. But in this interpretation, it's us who are falling through time, literally. I find that fascinating because it changes entirely how I think about the universe. I used to think of the "big bang" as a big explosion of little balls of energy (quarks, electrons, whatever) that eventually coalesced into matter, when enough time had passed and there was enough room for things to cool down. The part that I never understood before this interpretation is how "enough time could pass", when time itself was also supposedly expanding. But in fact with this interpretation, which I guess is probably more correct (?), space and time simply exploded and began expanding.. which is what we're told but it's hard to picture, exactly. But if you think about energy always moving at the speed of light, and initially all of it flying off in the same direction (time), then matter becomes those particles which were somehow slightly diverted onto the spatial axes -- momentum is conserved, just redirected. And if you think about particles being ripples in fields of non-zero constant energy, an interactions between the fields causing ripples to bump away from each other in non-time directions which we describe as space, this whole relativity thing, and the fact that electric field particles (photons) do not have mass and move at c, starts to make a bit of sense. It's crazy to think that what we perceive as time passing, the very possibility of things happening, is actually an emergent property of simple geometry and interactions of pure energy. The way I visualize it is: start two marbles rolling towards each other down an inclined slope. They bump, and bounce off in opposite directions on the X axis. Now imagine there is no table. Would the marbles "feel" anything in the vertical direction? Or would they only feel something in the horizontal direction? Time, for them, emerges from the fact that they can get closer, bump, and move off in the other direction. The other axis, which they are both moving very quickly in, they have entirely in common and they might agree with each other that it is simply a stationary frame which allowed the "bump" to happen. Same for us falling, unrelentingly and unstoppably, through time. (Maybe?)

TeMPOraL 8y ago
Except mass/energy must be really drawing a line across time dimension, instead of being points in it, right? Otherwise anything traveling in space - and thus slightly sideways - would immediately desync with the universe around it and interact only with emptiness?

dreamcompiler 8y ago

> This means that a photon, which travels at the speed of light, actually experiences no time at all. Yep. If a photon could talk, it might say "What is this 'time' thing you speak of?" And since time has no meaning, neither does 'traveling'. A photon is always 'everywhere it's ever been or ever will be' so it might also say "What is this 'space' thing you speak of?"

foobar1962 8y ago

>As you approach the speed of light, the amount of time you experience gets slower as compared to a stationary observer. My impression was that the wormhole was used as a "shortcut" between two distant places to avoid having to travel very fast. Imagine a race where everybody else runs the whole course but you take shortcut. You haven't physically travelled fast but your path has been shorter. I'd guess that Big Banking is blocking the development of this, it'd be a nightmare for inter-galactic ATM machines.