the relativity of time

[GarrotTheThief]

Time is relative.

Theoretically we can only go forwards in time meaning that even though time moves slower in some areas it never runs backwards.

But is our experience of time moving forwards subjective. Maybe every 1.5*10^500000000000000 years the polarity of time reverses. It's possible and can't be disproved unless I stand corrected.

But I'm pretty sure the apple doesn't feel itself get older like we do and so to the apple or any other object the idea of forward and backwards time is irrelevant and simply not true. In fact when we say time moves we are already wrong since we are using the analogy of an object moving to describe time. Technically time doesn't move at all actually but I admit it's a useful analogy and relatively true in an phenomenological sense which is why philosophy and science can't be separated at every level.

Anyways...what do you think?

 

[indra]

I read a book recently, Tetrascroll, perhaps you would like it.

 

[GarrotTheThief]

I read a book recently, Tetrascroll, perhaps you would like it.

thanks....I'll check it out now.

 

[hacbad macbar]

Time is relative.

Theoretically we can only go forwards in time meaning that even though time moves slower in some areas it never runs backwards.

But is our experience of time moving forwards subjective. Maybe every 1.5*10^500000000000000 years the polarity of time reverses. It's possible and can't be disproved unless I stand corrected.

But I'm pretty sure the apple doesn't feel itself get older like we do and so to the apple or any other object the idea of forward and backwards time is irrelevant and simply not true. In fact when we say time moves we are already wrong since we are using the analogy of an object moving to describe time. Technically time doesn't move at all actually but I admit it's a useful analogy and relatively true in an phenomenological sense which is why philosophy and science can't be separated at every level.

Anyways...what do you think?

Time doesn't exist. Time is psychological bias.

 

[INTP]

There is a theory that the universe grows for certain time and then collapses and that it has already done this many times. Or actually this was already said ages ago by hindus(if i remember right, maybe it was buddhists), but now there is some scientific theory about it as well.

 

[Ene]

I think the following article about the subject is quite interesting.

http://www.physicscentral.com/explore/plus/timeless.cfm

 

[GarrotTheThief]

I think the following article about the subject is quite interesting.

http://www.physicscentral.com/explore/plus/timeless.cfm

perfect article. thanks.

 

[Adam]

Great ELI5 explanation of spacetime:

Everything, by nature of simply existing, is "moving" at the speed of light (which really has nothing to do with light: more on that later). Yes, that does include you.

Our understanding of the universe is that the way that we perceive space and time as separate things is, to be frank, wrong. They aren't separate: the universe is made of "spacetime," all one word. A year and a lightyear describe different things in our day to day lives, but from a physicist's point of view, they're actually the exact same thing (depending on what kind of physics you're doing).

In our day to day lives, we define motion as a distance traveled over some amount of time. However, if distances and intervals of time are the exact same thing, that suddenly becomes completely meaningless. "I traveled one foot for every foot that I traveled" is an absolutely absurd statement!

The way it works is that everything in the universe travels through spacetime at some speed which I'll call "c" for the sake of brevity. Remember, motion in spacetime is meaningless, so it makes sense that nothing could be "faster" or "slower" through spacetime than anything else. Everybody and everything travels at one foot per foot, that's just... how it works.

Obviously, though, things do seem to have different speeds. The reason that happens is that time and space are orthogonal, which is sort of a fancy term for "at right angles to each other." North and east, for example, are orthogonal: you can travel as far as you want directly to the north, but it's not going to affect where you are in terms of east/west at all.

Just like how you can travel north without traveling east, you can travel through time without it affecting where you are in space. Conversely, you can travel through space without it affecting where you are in time.

You're (presumably) sitting in your chair right now, which means you're not traveling through space at all. Since you have to travel through spacetime at c (speed of light), though, that means all of your motion is through time.

By the way, this is why time dilation happens: something that's moving very fast relative to you is moving through space, but since they can only travel through spacetime at c, they have to be moving more slowly through time to compensate (from your point of view).

Light, on the other hand, doesn't travel through time at all. The reason it doesn't is somewhat complicated, but it has to do with the fact that it has no mass.

Something that isn't moving that has mass can have energy: that's what E = mc2 means. Light has no mass, but it does have energy. If we plug the mass of light into E=mc2, we get 0, which makes no sense because light has energy. Hence, light can never be stationary.

Not only that, but light can never be stationary from anybody's perspective. Since, like everything else, it travels at c through spacetime, that means all of its "spacetime speed" must be through space, and none of it is through time.

So, light travels at c. Not at all by coincidence, you'll often hear c referred to as the "speed of light in a vacuum." Really, though, it's the speed that everything travels at, and it happens to be the speed that light travels through space at because it has no mass.