Unless you’re white it wouldn’t be great going too far back in time.
And we have no idea how dystopian the future might be so you don’t want to get locked up and have to work in some Amazon prison warehouse.
So, going back or forward in time like Ebenezer Scrooge in A Christmas Carol would probably be ideal.
Is time a physical space that you can ‘travel’ through, I have heard all about those fancy space-time continuums or something like that but I want someone to explain this to my smol brain.
Sort of. You’re already doing it at this moment.
Einstein showed that time is not a separate space, but is actually the same as any other dimension. However, we have not found any way to reverse our direction so far. We can only choose a direction to move forward in. In fact, you’re doing so when you get in a car; you’re experiencing a minor change in how you’re moving through time relative to those around you.
It actually goes further than that. In spacetime you’re always going the same speed, the more in space, less in time.
At least from the special relativity perspective.
Really? Am I then going the speed of light in time?
Not quite, the true invariant quantity is the magnitude of the spacetime 4 vector, which depends on rest mass.
https://en.m.wikipedia.org/wiki/Four-momentum
I have to say, when I had it explained to me that everyone and everything was always moving at “c” and moving the vector more toward dimensions in space bled momentum from the momentum in time. It made a lot of things just make sense that previously did not.
Since you seem to know a bit about this, one thing always puzzled me. It would appear to me that there’s not really an “at rest” state in terms of movement in space. We’re on a planet orbiting a sun that orbits the central point of our galaxy, which in turn is also moving and perhaps orbiting something else even bigger. So, “at rest” is always subjective.
With that understanding, when we’re not moving from our point of view, we’re travelling through time at “c”. But in reality, it’s probably some lower value. Perhaps “0.8c” when viewed from the universe as a whole. But, that’s fine because we’re ALL moving at 0.8c through time, so who cares. But the twin paradox says if a twin travels away at a high speed then returns, they would have aged less. Bearing in mind all of the above, that makes sense, except for the general galactic movement.
Whatever is influencing us, there must be a 3d vector in space we, as a whole, are moving toward (probably constantly changing though). So, surely if you sent someone in the opposite of that vector, time for them would actually speed up rather than slow down. In fact, if you sent them exactly on that vector (and they followed any changes in 3d vector in real time) then returned. Would they not “catch up” and be on part overall with time passing?
Likewise, sending them on another vector would have the effect described by relativity, but there would be a skew from what is expected because the actual total vector would also be influenced by the speed we were already moving in another direction?
We wouldn’t see this skew on satellites and the like because they’re travelling with us on that vector but at a constant speed relative to us too. But sending away from us and back, we probably would. Or, am I again misunderstanding things on a fundamental level?
I waste too much time thinking about such weird things, I know.
Correct, that’s classical relativity, from before the notion of spacetime even existed.
It depends on who does the acceleration. Acceleration is key for the twin experiment, and the reason it works is because they are the one accelerating and decelerating. This requires “general” relativity to make sense, it can’t be explained by merely special relativity.
I don’t get what you mean here… which 3d vector are you referring to, and why should it exist? One of the important concept is that every reference frame is equally valid.
From one pov the earth sped up, instead of the twin’s spaceship slowing down. These are both valid interpretations. You can always catch up by doing the opposite of what you did before, but you need to look at acceleration for it to make sense. Acceleration is what turns your 4d vector so your reference frame changes, and you can sort of arbitrarily change “passing of time” if you can induce unlimited acceleration.
I feel like you’re rediscovering the idea of an “aether” which was disproven by Lorentz and Einstein.
Note that I’m not a physicist, just someone who loves staying up to date with modern physics!
I’m traveling through time right now!
Time is like space in that it can be distorted by gravity. If you get close enough to a black hole, then your perception of time will change compared to people on the outside. I don’t know why this is, it’s just a thing I know.
Also, as you move faster then your perception of time slows down. For example, if you went in a rocket at a good chunk of the speed of light then returned, you’d only experience one year passing but people left behind on earth would experience two years passing. You would both be objectively correct because the time actually moves at different rates (it’s not just a perception change in your brain). This is proven to work with GPS satellites. They move fast enough in orbit that their clocks slow down ever so slightly, and this needs to be accounted for so that we can have accurate positioning.
An analogy to understand this is to imagine a race across the desert. The finish line is 100m north of the start line. Two racers who move at the exact same speed are competing and set off at the same time. One person heads directly north, while the other one heads north-east. Who would get to the finish faster? Obviously the one who went directly north. Why? The other person wasted some of their travel on going slightly east. Now think of that same analogy with movement in time being north and movement in space being east. The faster you travel in space, the more of your movement through time is being “wasted”, so time slows down for you