Spin Time Questions

[Zinjanthropos]

May seem simple but….

If I were to place a dot on the edge of centre hole and one on outside edge of lp as if they were lined up like a spoke on a wheel and start spinning the record on turntable then obviously the dot on outside edge is moving faster. Because it’s moving faster does outside dot age slower than inside edge dot?

Proportionally sized disc with humans at both rims….. When directly facing towards each other would the light beam from one person to another be ever so slightly bent and only provide an illusion of a straight line?

From my reference point outside disc they both rotate with the same time or do they?

[stryder]

May seem simple but….

If I were to place a dot on the edge of centre hole and one on outside edge of lp as if they were lined up like a spoke on a wheel and start spinning the record on turntable then obviously the dot on outside edge is moving faster. Because it’s moving faster does outside dot age slower than inside edge dot?

Proportionally sized disc with humans at both rims….. When directly facing towards each other would the light beam from one person to another be ever so slightly bent and only provide an illusion of a straight line?

From my reference point outside disc they both rotate with the same time or do they?

I'm not 100% correct but it's a starting point to work with:

First you have to question what aging actually is. In the case of atomics you can imply that aging is the decay of state, which occurs over time. The decay rate is effected by gravity, namely something will decay quicker in space than it will down on earth. (The same can be said of aging).

That being said you could ask whether the points on the LP have the same mass and are effected by the same gravity, in which case there might be a slight increase in aging at the point with the most entropy. Since an LP is small compared to the planet however it would be so marginal it could be a "Trace" occurance.

In regards to a human sized version with a laser between two point, again any shift caused by momentum would be a miniscule trace. It would only likely be more noticable if you managed to spin the whole system up to the speed of light itself. (Which I'm pretty sure is impossible.) Even then it would just be a circle of light from our observation, you'd have to use a time capture method of photography to actually appreciate what it you'd be looking at.

As for relative frame of reference, If both observers are at the same distance from the centre of rotation and you observe them from the centre, then they would both have the same relationship to you, if not each other. Moving to a different position to continue observing would be like deforming a tetrahedron in regards to the topology of the trigonometry. (In other words it could mathematically be solved with triangles)

[confused2]

Maybe try a simpler question.

Because it’s moving faster does outside dot age slower than inside edge dot?

There's two effects Special and General Relativity.
SR says the outside dot would age slower.
Bacteria living on the outside of the disc would have to cling on to avoid being thrown off into the record collection so they'd be seeing a sort of negative gravity so the GR effect also tends to slow the aging of the outside dot.
With 82.7% confidence the outer dot ages slower than the inner one.

Proportionally sized disc with humans at both rims….. When directly facing towards each other would the light beam from one person to another be ever so slightly bent and only provide an illusion of a straight line?

Both people are accelerating so they're not in flat spacetime .. so as with seeing stars behind the sun during an eclipse .. they wouldn't see the beam as travelling in the straight line they would have expected if the disc wasn't rotating .. with 17.8% confidence.[Edit I had a 'discussion' with JamesR (SF) about this - we disagreed - I'm not claiming to know more than him - only that I am right and he is wrong]

From my reference point outside disc they both rotate with the same time or do they?

Yes.

[confused2]

More detail on the outside dot moving faster..
This is far too complicated to illustrate when going round in a circle.
So .. travelling in a straight line..
Alice is wearing a watch.. she is going to walk across a room. Bob keeps an eye on her.
She taps her watch against the wall when she starts and taps it against the wall when she gets to the other side.
For an observer (Bob) in the room the tapping events are (say) 20 feet apart. As far as the watch is concerned both taps are in the same place .. one tap is as good as another.
So Bob claims the watch has travelled 20 feet in the amount of time he measures.
Alice's watch claims it hasn't moved and will show less time has passed for it than for Bob.
I can't think of how to go further without any equations but the movement in one 'frame' and the absence of movement in the other is the reason for the times not being the same. Anyone want some (simple) equations?

[Zinjanthropos]

If the two dots were occupied by humans facing each other on a larger disc against a black background then I don’t see how they can know they’re moving should they themselves remain motionless.

However they could start walking with same speed along the edge they’re on. They have instructions that once they reach their starting point to look across as before they started.

Despite the fact the disc is rotating I don’t think they’d notice disc is spinning and should they be wearing watches the time for returning to their respective dots doesn’t change no matter which direction they travel along edge.( does it?) However one will return to their dot before the other because distances to return to respective dots differs.

At that point does the inside observer notice their counterpart has moved? With this info can one or both draw a logical conclusion that they’re on a rotating disc and one of them is moving faster than the other through some common medium?

By repeating walks but varying their directions of travel, right or left, I think they should be able cinch the fact they’re on a spinning disc. Could they conclude one is moving slower thru time?

* hope I worded that right ..lol

[confused2]

If the two dots were occupied by humans facing each other on a larger disc against a black background then I don’t see how they can know they’re moving should they themselves remain motionless.

Your spinning disc thing is actually a real thing (been there, done that) .. though apparently not in Canada ...
https://historydaily.org/the-rotor-ride

However they could start walking with same speed along the edge they’re on. They have instructions that once they reach their starting point to look across as before they started.

In the fairground thing the disc spins fast enough to keep people well stuck to the sides for safety. If we imagine one going rather slower..
If one walks backwards at the anything approaching the same speed as the disc rotates.. he drops off to the ground. One moving in the same direction (adding to the rate of rotation gets 'heavier'. Anyone (everyone?) can tell the disc is rotating by looking at the girls skirts.

Agree so far?

[Zinjanthropos]

Worded it wrong. These guys on the dots don’t know the disc they’re standing on is slowly spinning. They each go for a walk along their respective edges. Guy on inner edge doesn’t have far to go before he’s right back where he started, other guy is going to take a while.

Inner guy looks across and notices his counterpart isn’t where he used to be. He’s moved a little in one direction. Can he now conclude the disc they’re on is in a spin?

I don’t think it matters what direction they move along respective edges even if disc is in the spin. Walking at same speed means they each go same distance in same amount of time. No?

[confused2]

Worded it wrong. These guys on the dots don’t know the disc they’re standing on is slowly spinning. They each go for a walk along their respective edges. Guy on inner edge doesn’t have far to go before he’s right back where he started, other guy is going to take a while.

Sorry, I'm not seeing something already. I thought they were on the edges of a large horizontal disc, facing each other. Then you say 'inner edge' and my sort of record disc only has one edge .. I'm sure it's me but can you help?

[Zinjanthropos]

Worded it wrong. These guys on the dots don’t know the disc they’re standing on is slowly spinning. They each go for a walk along their respective edges. Guy on inner edge doesn’t have far to go before he’s right back where he started, other guy is going to take a while.

Sorry, I'm not seeing something already. I thought they were on the edges of a large horizontal disc, facing each other. Then you say 'inner edge' and my sort of record disc only has one edge .. I'm sure it's me but can you help?

How about two circular paths, one close to centre and the other near the edge.

[confused2]

Worded it wrong. These guys on the dots don’t know the disc they’re standing on is slowly spinning. They each go for a walk along their respective edges. Guy on inner edge doesn’t have far to go before he’s right back where he started, other guy is going to take a while.

Sorry, I'm not seeing something already. I thought they were on the edges of a large horizontal disc, facing each other. Then you say 'inner edge' and my sort of record disc only has one edge .. I'm sure it's me but can you help?

How about two circular paths, one close to centre and the other near the edge.

That would be immensely complicated (too complicated for me). The relative velocity would change horribly so SR is too complicated and the GR isn't nice either .. too many things to get wrong at the same time. Needs someone better than me and I'm not sure the inherent complexity would help to clarify anything anyway. Would you be happy with more detail on just the dot at the centre and one at the edge?