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empleat

Could cause and effect be broken, if time stopped?

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Posted (edited)

Hello,

i just want to ask a quick question: could cause and effect be broken, if time stopped? Question is, even if it did... could anything happen due to time stopped? And by that i don't mean classical event in time, by that i mean anything physical, or quantum. Perhaps some interaction of sorts, i don't know... Because for example: some theories say, that time is emergent.

Thanks for answer.

Edited by empleat

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It seems to me that cause and effect are based on events, if there was no time there would be no events, so, no cause and effect.

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I can't see how you could possibly break causality.

Time is relative, and time is what clocks measure. Time, or a clock, will stop on a black hole event horizon according to an observer outside the horizon. That doesn't break causality, which is perfectly fine with that type of "time stopping".

But you probably mean if all of time stops at once? That doesn't make physical sense in the universe as we know it (ie. described by General Relativity) so you'll have to specify what you mean by it. However, if you came up with an arbitrary definition of simultaneity that made physical sense for a particular abstract observer, and stopped all physical processes at the same time, then "later" (still letting time pass for the non-physical observer, whether that's even meaningful) they all continued as they were before and at the same time, then not only would causality not be broken, I don't think any physical thing would be able to measure any difference having happened at all... I think. So whether everything stopped and started all together, or didn't, doesn't even have any bearing on reality, which I think would make it basically a philosophical exercise rather than a scientific question. Even though things wouldn't all stop at the same time according to others, if everything stopped and started in the same way, I don't think they could possibly notice.

However, you might be able to contrive some meaning of "stopping time" that breaks causality. For example if you temporarily stop time for some clocks but locally let a physical object keep moving as if time wasn't stopped, that object can move faster than light as measured by the stopped clocks, and that can break causality.

 

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Posted (edited)
On 8/20/2020 at 7:10 AM, md65536 said:

However, you might be able to contrive some meaning of "stopping time" that breaks causality. For example if you temporarily stop time for some clocks but locally let a physical object keep moving as if time wasn't stopped, that object can move faster than light as measured by the stopped clocks, and that can break causality.

 

Interesting. I thought everyone have their own clocks. I don't even know what to imagine behind that. Than how could be some object measured by other clocks, which have stopped?! Has it not its own clock? I watched Dark recently. And there was something about time stopping, which broken cause and effect. And allowed time travel to any time, with a time machine. Also there was disconcerting idea, we may relive same lives over and over. I already heard about that, there are many theories about that actually... So i was curious, if anyone could ever change that theoretically. Because information cannot be destroyed and time doesn't go anywhere: we exists in past,present and future - at the same time. I am afraid, that we may be reliving same lives over and over, or different ones, which is even worse... Literally anything could happen...

Edited by empleat

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45 minutes ago, empleat said:

I thought everyone have their own clocks. I don't even know what to imagine behind that. Than how could be some object measured by other clocks, which have stopped?!

Sure, everything has their own clocks. I'm giving an example the breaks the laws of physics. For example, say you have two observers A and B, a light year apart, and A sends a message to B. Then you stop time for A and B, but let the message keep going. Then start time so that A and B measure the message taking say only an hour, as if it instantly jumped across space while they and their clocks were stopped.

 

But then suppose there's another observer C moving at high speed relative to A and B. Normally, if A and B, in their rest frame, are a light year apart and there's an event at A and another at B one hour later, then C can be moving such that the event at B happens before the one at A, which is normally fine because the events aren't causally related. But if A can send a message to B, that is causal relation, and if C can observe B receiving it before A sends it, causality is broken. By ignoring the laws of physics, I made an example that doesn't make sense, and is a paradox. For C, "time starts again" first, before B receives the message, then later "time stops" after A sends it. As long as you're ignoring the laws of physics, you could make up any number of ways to resolve this paradox, and if you're just making things up, then yes literally anything could be imagined.

 

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12 hours ago, md65536 said:

Then you stop time for A and B, but let the message keep going.

How do you do that?

The message is relative to the reciever, when they get it, until then it's relative to the source; either way time is only stopped for one relative to the other, the message doesn't care which one.

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11 hours ago, dimreepr said:

How do you do that?

It's a fictional example. Everything has their own clock, and they can't all be stopped "at the same time". In fiction where "time stops" in some contrived way, some observers' clocks stop while other observers keep observing, because if there's nothing to observe that some clocks have stopped, the stop is meaningless and doesn't look good on tv etc. When they use "time is stopped" for things like time travel, it's some made up way with most likely no basis in reality.

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12 hours ago, md65536 said:

It's a fictional example. Everything has their own clock, and they can't all be stopped "at the same time". In fiction where "time stops" in some contrived way, some observers' clocks stop while other observers keep observing, because if there's nothing to observe that some clocks have stopped, the stop is meaningless and doesn't look good on tv etc. When they use "time is stopped" for things like time travel, it's some made up way with most likely no basis in reality.

OK, so what's your point?

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My point is that "if time stopped" doesn't mean anything on its own, it needs more details, and those details can describe something that breaks the laws of physics including causality, or something that doesn't.

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22 hours ago, md65536 said:

My point is that "if time stopped" doesn't mean anything on its own, it needs more details, and those details can describe something that breaks the laws of physics including causality, or something that doesn't.

My infinate improbability drive can get there before you send the message; what's your point now???

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Ill-posed questions are missing one or more of the following properties ... 

  1. a solution exists,
  2. the solution is unique,
  3. the solution's behaviour changes continuously with the initial condition

From      https://en.wikipedia.org/wiki/Well-posed_problem

Maybe the OP can scrap this one, and try again.

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