Special Relativity. Lifetime.

[Alex K]

Time pops up a lot in any physics discussion because it's one of the basic dimensions in which we exist. It's exceptionally difficult to describe our universe without bringing time into it, so yes, it pops up a lot in physics.

I question whether time exists independent of a mind, but I suppose I don't know enough about the physicists view to argue against it at the moment.

Whether time exists independent of the mind or not, I don't even know exactly what that means. All I can tell you is, compare any two physical processes at relative velocity v to each other, with appropriate clock synchronization beforehand, and you will measure exactly the discrepancy in their rates as predicted by f'=f* sqrt(1-v^2/c^2).

[BrianSoddingBoru4]

I question whether time exists independent of a mind, but I suppose I don't know enough about the physicists view to argue against it at the moment.

Whether time exists independent of the mind or not, I don't even know exactly what that means. All I can tell you is, compare any two physical processes at relative velocity v to each other, with appropriate clock synchronization beforehand, and you will measure exactly the discrepancy in their rates as predicted by f'=f* sqrt(1-v^2/c^2).

Pfft.  Yeah, like I'm going to spend an hour synchronizing all the clocks in my house - alarm clocks, wall clocks, desk clocks, watches, a microwave, the stove, the fridge, and the owl on the mantlepiece with a clock in its stomach. 

Hard pass.

Boru

[John 6IX Breezy]

Clocks need to be synchronized, presumably, because we can observe discrepancies in their synchronization if they emerge. That is all we have access to, not time. I don't know how atomic clocks work, but I doubt they are tapping into anything called time either, they are independent of it. All clocks present some form of observable motion or change to our minds, and our minds abstract the notion of time from this physical motion.

The formula doesn't change because of this, but perhaps the conclusions drawn from it do. Again, disclaimer, I don't fully know what physicists mean by terms such as time dilation. But it seems incorrect to conclude time has changed in any way based on the physical changes of a clock. It is like assuming time stops whenever I stop a clocks hand from moving. Or perhaps like having a ruler made of rubber, and assuming the world is constricting whenever I stretch the ruler out.

[Alex K]

Clocks need to be synchronized, presumably, because we can observe discrepancies in their synchronization if they emerge. That is all we have access to, not time. I don't know how atomic clocks work, but I doubt they are tapping into anything called time either, they are independent of it. All clocks present some form of observable motion or change to our minds, so we can abstract the notion of time from it.

The formula doesn't change because of this, but perhaps the conclusions drawn from it do. Again, disclaimer, I don't fully know what physicists mean by terms such as time dilation. But it seems incorrect to conclude time has changed in any way based on the physical changes of a clock. It is like assuming time stops whenever I stop a clocks hand from moving. Or perhaps like having a ruler made of rubber, and assuming the world is constricting whenever I stretch the ruler out.

You can always take the position that time as Das Ding an sich is never accessible directly, and I cannot argue with that. What I can say is that all physical processes are affected by dilation the same way, and it therefore is in any meaningful sense a dilation of time. It would be a mistake to just view it as a "malfunctioning" of a clock bc all processes, even the most fundamental ones we know such as particle decay, are affected by it the same. Same goes for curvature of spacetime which is directly observable as gravitational redahift. It is a slowing of time itself in any sense if all temporal processes we know adhere to it.

[John 6IX Breezy]

You can always take the position that time as Das Ding an sich is never accessible directly, and I cannot argue with that. What I can say is that all physical processes are affected by dilation the same way, and it therefore is in any meaningful sense a dilation of time. It would be a mistake to just view it as a "malfunctioning" of a clock bc all processes, even the most fundamental ones we know such as particle decay, are affected by it the same. Same goes for curvature of spacetime which is directly observable as gravitational redahift. It is a slowing of time itself in any sense if all temporal processes we know adhere to it.

Right, I agree it is not an isolated malfunctioning of the clock, and that what is happening to it is also happening in its vicinity. But what appears to be happening is a slowing down of localized motion, or a slowing down of localized change, not a slowing down of time. I don't think its possible to observe a universal slowing down of time, for example, because we would slow down with it, and everything we observe would appear constant. The only way to observe a clock ticking slower, or particles decaying slower, is if they are in fact ticking and decaying slower while time remains constant.

Perhaps relativity already takes this into account, and trades a universal notion of time, for a more localized view of time, I'm not sure. My proposition would be that time is neither universal nor localized, but psychological; and we perceive a localized slowing down of motion as a slowing down of time. I think red-shifting and other doppler effects are more to my point; we perceive the siren of an ambulance as slowing down because the soundwaves are being stretched out as it moves away from us, not because time is slowing down.

I haven't heard of gravitational redshift before, so I'll have to look that up later.

[Peebothuhlu]

At work.

There was a documentary ages ago with Peter Ustinov hosting.

It was the first time I'd seen the "Black hole time dilation with twins" explained.

Namely that; If you have two twins. One orbits the black hole out at a 'Safe' distance while the other has an orbit that slowly draws closer to the 'Event horizon' of the black hole. (The point at which nothing, even photons, can escape)

From the point of veiw of the 'Safe' twin. Reality carries on as normal but they see their 'Descending' twin appear to slow down.... possibly even seeming to 'Freeze' and stop moving altogether.

While, to the twin drawing ever closer and closer to the event horizon, everything also seems 'Normal'. However everything further away from their position, or 'Further out' from the event horizon, seems to 'Speed up'. Untill the outside reality simply passes by in a blurr.

Hope my recounting of the tale helps some.

Cheers.

[Alex K]

@Breezy,
General relativity does that precisely - there is no global universal time a priori in general relativity. Special relativity unites space and time and mixes them up differently for different observers, not so much locations - however, in the GR description of spacetime everything is indeed localized. The extreme example are black holes where time stands still on the horizon as seen from outside, but runs on for someone falling in.

[John 6IX Breezy]

@Breezy,
General relativity does that precisely - there is no global universal time a priori in general relativity. Special relativity unites space and time and mixes them up differently for different observers, not so much locations - however, in the GR description of spacetime everything is indeed localized. The extreme example are black holes where time stands still on the horizon as seen from outside, but runs on for someone falling in.

Hmm I see, the idea makes sense to me when time is divorced from the equation. Gravity would affect the way things move, and that's it; at the very least it slows you down when you jump. I'm not entirely sure I understand why an increase in gravity constitutes a slowing down of motion in a more pervasive way, but given that it does and it affects even your neurons, meaning you process information slower, it makes sense that near a black hole you see yourself as moving at normal speed and time, because your mind has slowed down along with your surroundings. You therefore perceive time outside the black hole as moving faster, because motion is unaffected out there. It sounds similar to how weightlessness is achieved by falling inside a plane that's also falling, your mind perceives it as floating.

Black holes, then, seem similar to moving in a pool full of water, where your movements appear slower to those outside of the pool. Perhaps the only difference is that water only affects the movement of your body, not your brain. As such your mind hasn't slowed down, and you can still experience your own body moving slower through the water. But if the pool did affect your neurons and slowed them down the way gravity does in a black hole, perhaps you would in fact feel as if you're moving normally through water while the outside world moves faster.

[Peebothuhlu]

At work.

Uhm...... it's not just the neurons slowing down when getting closer to the event horizon. It's everything in and of the vicinity. You/yourself see no difference in anything around you/your immediate vicinity. The further 'Out' and away things are the faster they would appear to be.

The person near the event horizon would see no difference in the space-ship around them. See no difference in their regular, normal breathing pattern or heart beat rate etc.

To the person watching from 'Further out' everything about the closer person and their vessel would appear to slow down.

[John 6IX Breezy]

Well right that's my point. The only difference is perhaps that I'm saying the mind slows down not time