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Author Topic: Can any two events in the universe happen at exactly the same time?  (Read 2996 times)

Offline galaxysim

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Can any two events in the universe happen at exactly the same time?

I got asked this and i really could not answer it to my satisfaction

https://en.wikipedia.org/wiki/Planck_time [nofollow]

Anyone want to dazzle me with some hard science ?


 

Offline Pmb

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Can any two events in the universe happen at exactly the same time?

I got asked this and i really could not answer it to my satisfaction

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

Anyone want to dazzle me with some hard science ?
Classically the answer is yes. If you were to ask this and wanted to answer using quantum mechanics then it might be no. In non-relativistic quantum mechanics there's no problem with that and with both special and general relativity there's no problem with that. All of these theories say that it's possible. However if you turn to quantum gravity there is no answer because as of yet there is no quantum theory of gravity.
 

Offline galaxysim

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FYI this is the  'simple answer' we got to in the debate elsewhere

If the number of events that can happen is larger than the smallest unit of time we can measure then some of those events must happen simultaneously.

By reducing 3d space+1d of time to 1d of space we get

 'there are so only many matchsticks you can lay end to end on a ruler without them touching'







« Last Edit: 06/07/2013 17:02:44 by galaxysim »
 

Offline Pmb

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Correction - I forgot to mention the fact that in order for two events to happen at the same time their spacetime interval must have a spacelike spacetime interval.

Keep in mind that time between two events is observer dependant. Different observers in different inertial frames of reference will generally measure different times between two events, the time difference being a function of the relative speed between the two events. So in cases where the events have a spacelike spacetime interval there is an inertial frame of reference in which the events happen simultaneously.

Thanks for asking this problem. If you didn't then I never would have realized that I forgot to mention the spacetime interval in my webpage on spacetime. I need to go back and add a section on the geometry of spacetime.
 

Offline galaxysim

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thx for reminding me also, lol

the other debate was bogged down in 'lay comprehension issues' we never quite got to the finer details, lol

science is particularly hard if you are coming to it late and are rushing in from the side rather than climbing up the mountain of comprehension from bottom to top
 

Offline galaxysim

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@PBM agree / disagree

At the quantum level, yes. Two single electrons that are entangled are *exactly* the same particle, utterly indistinguishable other than that they occupy different locations in space, and whatever happens to one happens to the other, regardless of distance. It is not known why such entangled particles can be separated in space, but they can be, and it is believed that the interaction between them is *instantaneous* since empirically it is has been shown that their synchronization speed is at *least* 10,000 times faster than the speed of light, and it has been shown they can be separated by many miles and still have such synchronization happen, and it is believed they can be separated arbitrarily far from each other.
 

Offline Pmb

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Quote from: galaxysim
At the quantum level, yes. Two single electrons that are entangled are *exactly* the same particle,...
I disagree. I can't understand why you'd make a statement like this. Just because they're indistinguishable it doesn't mean that they're the same particle. In fact it's not clear what you mean by such a statement. E.g. consider two particles which scatter off each other and you can't tell which is which. Later on one particle is detected in one detector and the other is detected in another detector which is spatially separated by a large distance. Please explain what you mean in an operational sense when you say that they are the same particle.

Thank you.

Quote from: galaxysim
utterly indistinguishable other than that they occupy different locations in space, and whatever happens to one happens to the other, regardless of distance.
That statement is incorrect since their entanglement only lasts until the first measurement is made. After that they are no longer entangled.

Quote from: galaxysim
It is not known why such entangled particles can be separated in space, Ö
Who made that claim? Itís intuitively obvious even to the most casual observer why that statement is wrong. It canít be said that we donít know why particles can be in different places at the same time. Itís just so simple that we canít describe it.

Quote from: galaxysim
but they can be, and it is believed that the interaction between them is *instantaneous* since empirically it is has been shown that their synchronization speed is at *least* 10,000 times faster than the speed of light, and it has been shown they can be separated by many miles and still have such synchronization happen, and it is believed they can be separated arbitrarily far from each other.
I disagree. People get the wrong impression about entanglement as if there is a causal relationship where measurement of one particle has a physical relationship with the other article. Thereís nothing about quantum mechanics that would make such a statement true.
 

Offline galaxysim

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It was a  reply someone else made....i haven't brushed up much on entanglement recently so i was in a poor state to dissect it..thought you might have  spare minute to run through it. Thx for your time.

The world is complex, and we feeble minded humans tend to over simplify I guess there is a practical limit to how well the public can be educated, Most people go shopping at Dunning and Kruger


It would be nice if we all had a PHD in physics...it would certainly help with the stamp collecting

We have such a crappy education system and the world imposes many more immediate pressures.
The power of plausible speech is near universal the ability to think like an experienced scientists far rarer.

Information is everywhere, but wisdom as ever is in short supply.

I think  there would still be many educational issues even if the average IQ of the populace was 130

The lack of scientific comprehension in government the 'actual' societal crime
education  efforts should be focused on government and decision makers. They are the ones that impact and influence the populace...bit off topic, but education...or perhaps the increasing the  utility of education is a primary goal of the naked scientist project.

« Last Edit: 06/07/2013 19:54:03 by galaxysim »
 

Offline evan_au

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Yes, two events in the universe can happen at exactly the same time.

In fact, a surprisingly large variety of events which occur at different points in space can be made to look as if they are simultaneous, provided you are free to select the frame of reference of the events and the observer(s).

To overcome the inherent ambiguity of measuring time, in relativity it is simplest if the observer(s), and the events being monitored are all collocated, in the same inertial frame of reference.
 

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