Arrow of time and travel at the speed of light

[BernieM]

How do you define time or space without reference to something else?

 

[Dale]

Lots of people don't like it when I tell them this, but both space and time are human inventions.

I don't particularly like this either. The words "space" and "time" are human inventions, as are the mathematical and other symbols used in relativity. But the things that those symbols and words represent are not human inventions.

 

[BernieM]

Like space and time, I think potential is a pure property of value as well, but as I said, I haven't found a way to express it in a scientific way yet (maybe never will?.) In a way dark energy and dark matter are similar. They are postulated to exist by effects we observe in our universe, yet by nature, since they are 'dark' and haven't yet been observed, it's kind of hard to say what they are or aren't in reality. Perhaps potential is just dark energy or something, or a manifestation of it. Potential seems to be an objective form of probability/possibility, on which quantum mechanics is based. So I would think that QM would have to deal with 'from where does probability in the universe arise' on a theoretical level.

But I won't belabor potential so I can keep out of trouble here on the forums.

In regard to the photon scenario, I have gained some insight that has value to me such as the rest frame contradiction. As well as the other option in my original post that set me straight there. In general the answers have been helpful and this thread has been productive for me. Although the scenarios people present of 'how a photon sees the universe' have been marginalized, I have yet to actually find a 'proper' model presented in a relatively simple to understand way. I would find that very helpful. That if the currently offered scenarios are incorrect in some way, it would be valuable to have a correct representation made.

One final question comes to mind:
If every particle in the universe were to be considered an observer, wouldn't every observer perceive a different universe than every other observer?

 

[Herman Trivilino]

How do you define time or space without reference to something else?

What you define is the operation used to measure them.

 

[Drakkith]

If every particle in the universe were to be considered an observer, wouldn't every observer perceive a different universe than every other observer?

I'd say that each observer perceives the universe slightly differently since all other objects are positioned differently and may have different properties (like relative velocity) with respect to the observer. In other words, electron A sees electron B on its right side and nothing on its left, while B sees A on its left and nothing on its right, leading to unique perspectives.

 

[Dale]

Although the scenarios people present of 'how a photon sees the universe' have been marginalized, I have yet to actually find a 'proper' model presented in a relatively simple to understand way.

A proper model of what? Of how a photon sees the universe?

There isn't one. It is improper and self contradictory at its core.

 

[PeterDonis]

This seems like a good point at which to close the thread.