Time flows in One Direction

[Hermit]

I thought the ideas Einstein presented suggests that all units of times exist, as do all units of spatial dimensions. So yes, you can go dig up your dead granny, but that doesn't suggest that time flows forward. Or something like that. My head hurts...

Time is a concept we abstract from events - which cannot be reversed.

[cronus]

When you are born time is fast because the universe is nearer a well ordered set and things don't get so messy as they happen, but when you die the universe is less well ordered and time is slower. After all time is simply things happening in a sequence of events. So it stands to reason that your local perceptions of time and your conscious perception of the universe should end together. The universe you consciously perceive is a illusion, that ends when you die. And so you see? When you are realistic enough then the world will end at the same time as you do? Maybe it will be asteroid out the blue or maybe a world war...but this world will end...end...end...

https://en.wikipedia.org/wiki/Boltzmann_brain

[pErvinalia]

I thought the ideas Einstein presented suggests that all units of times exist, as do all units of spatial dimensions. So yes, you can go dig up your dead granny, but that doesn't suggest that time flows forward. Or something like that. My head hurts...

Time is a concept we abstract from events - which cannot be reversed.

Flow of time, you mean. Time isn't an abstraction, anymore than length is.

[pErvinalia]

When you are born time is fast because the universe is nearer a well ordered set and things don't get so messy as they happen, but when you die the universe is less well ordered and time is slower. After all time is simply things happening in a sequence of events. So it stands to reason that your local perceptions of time and your conscious perception of the universe should end together. The universe you consciously perceive is a illusion, that ends when you die. And so you see? When you are realistic enough then the world will end at the same time as you do? Maybe it will be asteroid out the blue or maybe a world war...but this world will end...end...end...

https://en.wikipedia.org/wiki/Boltzmann_brain

Huh? Just because you aren't there to perceive it doesn't mean time and the universe cease to objectively (nor subjectively) exist. It does for you, but not other observers.

[Hermit]

Time isn't an abstraction, anymore than length is.

Define time. And length, for that matter.

[pErvinalia]

Well they are physical dimensions. They aren't abstractions. I really think you meant "flow of time" was the abstraction. That's a fairly common concept in physics (well, it was at least before this latest quantum weird shit experiment, possibly).

[Hermit]

I really think you meant "flow of time" was the abstraction.

WTF gave you that idea? I did say

Time is a concept we abstract from events

didn't I?

Not that it matters. "Flow of time" is just a flowery re-expression, a verbose way of saying "time".

Anyway, I'm glad you concede that they are physical dimensions. Now define time (and length) without reference to them, thanks.

[pErvinalia]

WTF gave me that idea? Because I've never heard of anyone consider time an abstraction. But plenty of people consider the "flow of time" an abstraction. I think you are confusing yourself. Time is a physical dimension. By definition it's not an abstraction.

[pErvinalia]

And "flow of time" and time aren't equivalent, just the same way that direction and vector aren't the same thing.

[Jason]

The top answer is very clear and understandable - and from a PhD student!

https://www.quora.com/How-plausible-is- ... -dimension

[JimC]

Many concepts in physics only require time to be plugged into a formula as a duration, a perfectly scalar number with no direction implied.

[mistermack]

I think, if every process in the universe slowed down equally, ie, if time slowed, nobody would be aware of it. Your bodily processes would slow to the same degree as everything else.
Throw a ball up in the air, and it would rise and fall slower, but relative to the thought processes in your brain, it would happen just the same as now.
Similarly, if time for the whole universe sped up, we would all be unaware of it.
I'm pretty sure that if time reversed for the whole universe, again we would be unaware it was happening.

It's only local time reversing, while for the rest of the universe, time goes forward, which is impossible.
It's theoretically possible for stuff that goes through a worm hole, (if they exist) but that would destroy anything resembling a human.

[pErvinalia]

The relative time thing is Einstein's relativity. The faster you move in relation to some other frame the slower you experience time. Acceleration plays a part in this process too. Don't ask me to explain it. I've always had trouble understanding why a twin who takes off from earth and accelerates away to near the speed of light and then turns around and comes back and then decelerates will have aged less than the twin who stayed on Earth. This to me seems to imply that the Earth is a privileged frame of reference but brains bigger than mine have apparently explained why this isn't the case. Something something General Relativity....

[rainbow]

I think, if every process in the universe slowed down equally, ie, if time slowed, nobody would be aware of it. Your bodily processes would slow to the same degree as everything else.
Throw a ball up in the air, and it would rise and fall slower, but relative to the thought processes in your brain, it would happen just the same as now.
Similarly, if time for the whole universe sped up, we would all be unaware of it.
I'm pretty sure that if time reversed for the whole universe, again we would be unaware it was happening.

Exactly!

It's only local time reversing, while for the rest of the universe, time goes forward, which is impossible.

Not quite, but then you'd need multidimensional time.
...which would require a super-dimensional intelligent being to experience it. Data overload would be problematic.

[Brian Peacock]

Many concepts in physics only require time to be plugged into a formula as a duration, a perfectly scalar number with no direction implied.

Indeed. Running the hypothetical clock backwards led to the postulates which ultimately discredited the steady state universe theory, which was quite a big deal at the time.

https://en.wikipedia.org/wiki/Steady_State_theory