Is Simultaneity Relevant in Intergalactic Communication?

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Discussion Overview

The discussion revolves around the relevance of simultaneity in the context of intergalactic communication, particularly focusing on a hypothetical scenario involving a message sent from Planet X to Earth and the timing of events related to a Nobel Prize. The scope includes conceptual exploration of time, causality, and the implications of special relativity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the message from Planet X takes ten years to reach Earth, raising the question of whether the Nobel Prize was received before the message was sent.
  • Another participant argues that an effect cannot precede its cause, questioning the validity of the scenario.
  • A different participant asserts that there is no absolute time throughout the universe, implying that simultaneity is relative.
  • One participant acknowledges that while simultaneity is relative, concepts of time still exist, citing the Cosmic Microwave Background (CMB) as an example.
  • Another participant emphasizes that the events of sending the signal and receiving the Nobel Prize could be perceived in reverse order in certain reference frames due to their space-like interval in Minkowski space.
  • One participant expresses confusion about how the question relates to relativity, suggesting a misunderstanding of time dilation.
  • Another participant proposes that defining simultaneity could help clarify the discussion and avoid what they perceive as trivial questions.

Areas of Agreement / Disagreement

Participants express a range of views, with some agreeing on the relativity of simultaneity while others contest the relevance of the question to physics. There is no consensus on the implications of the scenario or the validity of the question itself.

Contextual Notes

Participants reference concepts such as "space-like" intervals and "light cones" without fully resolving the implications of these terms in relation to the scenario. The discussion includes assumptions about the nature of time and causality that remain unexamined.

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Suppose someone from Planet X, In another part of our galaxy, is trying to communicate with the earth. He sends out a message. This is, of course an electromagnetic wave that travels through space with the sepeed of light. Assume that it takes ten years for the message to travel to earth. Twelve years before a radio astronomer on Earth receives the message, the astronomer has received a nobel Prize.

Does this permit us to say that he received the prize before the message was sent from planet X?
 
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Where does Planet X come into the picture? btw, an effect cannot precede its cause.
 
Sorry about that... they are the same planet...
 
How is this a "relativity" question? In fact, how is this even a physics question?

Zz.
 
there is no absolute time throughout the universe by which absolute simultaneity can be measured
 
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Karma said:
there is no absolute time throughout the universe by which absolute simultaneity can be measured

Well, there sort of is. For example, we often talk about how the CMB was emitted 300,000 years after the Big Bang, and we say that the universe is 13.7 billion years old. While simultaneity is relative, special relativity does not void the concept of time altogether.

By the way I'm fairly certain that the answer is yes, the astronomer received the prize before the message was sent. As someone else said, I'm not sure that this is actually a physics question.
 
My initial response still holds true.

Edit: OK, I just reread your question and see that you've changed it. So you might not see how the entire cause-effect thing applies to your situation.
 
Karma said:
Suppose someone from Planet X, In another part of our galaxy, is trying to communicate with the earth. He sends out a message. This is, of course an electromagnetic wave that travels through space with the sepeed of light. Assume that it takes ten years for the message to travel to earth. Twelve years before a radio astronomer on Earth receives the message, the astronomer has received a nobel Prize.

Does this permit us to say that he received the prize before the message was sent from planet X?

I still don't see what is "relative" here, or anything to do with relativity. Either you have severely misunderstood "time dilation" in SR, or this has nothing to do with it at all.

Zz.
 
I disagree with everyone. First, this is a perfectly valid question, and I think, a profound one. Second, the simple answer is no, there will exist a reference frame where these events happen in reverse order. This is because the two events, the sending of the signal and the awarding of the nobel prize, are related by a "space-like" interval in "Minkowski space". They happen outside each other's "light cone". i.e. they happen at a proper distance of 10 light years apart, and only two years apart in proper time. If they were "time like" then one could say with certainty that one happened before the other. i.e. If they happened one light year apart (proper length) and 10 years apart (proper time), then no "lorenz transformation" would reverse the order.

For more info, google the terms I put in quotes.
 
  • #10
is simulataneity is something we should define? won't it be better if we were confined with oer own world ('within' our time cone) coz' that would shut stupid questions like these!
 

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