[Q] How would instant communication change what we know about the universe?

[Moontanman]

If someone came up with a way to detect an event instantaneously how would this change our way of thinking about the universe?

 

Would it just mean we could get information about a distant supernova the instant it happened instead of having to wait several years or would it have a more fundamental meaning about the universe?

 

Would it change everything or not?

[Moontanman]

I guess I've finally asked a stupid question :)

[modest]

Not at all a stupid question.

 

The problem is that flt communication (which instantaneous communication is) means it would be fairly easy to construct a method of sending a message into your own past. This happens because our plane of simultaneity depends on our motion. If I'm right next to Bob, but Bob is moving faster than me while we both send messages to the moon that travel instantaneously to the moon then the two messages will reach the moon at different times.

 

Since Bob is moving relative to me then his idea of the moon's "right now" is different from my idea of the moon's "right now".

 

If Bob could see the moon as it exists "right now" then all he would have to do in order to see the moon's past is to move away from the moon with some speed. If he moved toward the moon he would see the moon's future.

 

For a method of using this peculiarity to send messages into one's own past, here's a site: The (Why No) FTL FAQs Page (OA), under "A brief essay on causality"

 

Sending a message to your own past would break down causality making paradoxes that don't seem to have solutions.

 

~modest

[Moontanman]

I am going to disagree here and this is the reason why, if indeed both parties had an instant comlink, then Bobs motion would have no bearing on how fast his view of the moon was. You could send messages back and forth and every time everyone would see the mess at the same time regardless of their time frame or any relativistic effects. Instant communication would not be effected by time dilation. The only thing that would cause it to appear as time travel would be if you were relying on light to check your comlink. I know I must be wrong but it's how I see it, the time travel aspect is an illusion caused by the speed of light being used as your check.

 

I read the link and it still looks like to me that everyone is hiding behind the speed of light. In our thought experiment about the jumping space craft we saw how it would look to the guy in the ship as though clocks on the earth were going backward as he progressed forward but it was just an illusion caused by jumping ahead of the light traveling from the earth. I guess I need it explained to me in baby steps. How would me seeing a nova 1000 light years away the instant it happened be communication with the past?

[modest]

... if indeed both parties had an instant comlink, then Bobs motion would have no bearing on how fast his view of the moon was.

 

But, it would. If Bob and Alice have an instant com link then they could talk normally while Bob and Alice are motionless to one another. If Bob suddenly started moving away from Alice at near the speed of light then his instant com link would suddenly be talking to a younger and younger Alice. Each subsequent "instant" message he sent to her would reach a younger Alice. This is absolutly demanded by the theory of relativity.

 

Relativity is as much about simultaneity as it is about time dilation. It might help to read:

 

Rietdijk-Putnam argument - Wikipedia, the free encyclopedia

 

Things that are simultaneous to me (ie my idea of "right now") changes as I accelerate.

 

~modest

[Moontanman]

Ok, I read your link and I think I am going to be able to show just how ignorant of reality I really am but while I'm getting my thoughts together on this lets talk about the idea of me being aware of a nova 1000 light years away the instant it happened. How would this relate to the idea of FTL communication involving a time paradox?

[modest]

The easiest way to think about it (at least for me) is to imagine you've got a friend at the nova 1000 light years away. If you send a message to him instantly then he could accelerate away from you as soon as he gets the message. He wouldn't have to accelerate very fast since he's a good distance away. As soon as he gets a bit of velocity he could send the same message back to you and the message would arrive before the original message was sent.

 

If my back-of-the-envelope math is correct, a person 1000 ly away would have to accelerate to about 50,000 meters per second to send a message one day into earth's past. The same thing could be done without a distant helper (but entirely on earth) if faster speeds were used for example with a particle accelerator.

 

But, the idea is that the fella out in deep space has his "present moment" or "plane of simultaneity" shift when he accelerates. If he accelerates away from earth then his present moment (or his present moment view of the earth by your description) will shift into earth's past.

 

~modest

[modest]

The same thing could be done [sending a message back a day] without a distant helper (but entirely on earth) if faster speeds were used for example with a particle accelerator.

 

I take this back. :) A single message where both the sender and receiver are on earth would not be able to go back more than about a tenth of a second. It still would be possible to send a message back days or months or whatever, but the system would have to do it in steps—successively catching messages a fraction of a second from the future and sending them a fraction of a second into the past.

 

Such a relay system would be crazy-fun to design :)

 

~modest

[Michael Mooney]

Hi Moontanman,

As per your suggestion I will address your last question posted in my thread here.

 

I asked this question again in the question and answers section so maybe we should move it there but I would like to say that I see no reason the think that the ability to detect something happening the instant it happens would confer some sort of omnipresent view point. From my perspective the speed of light is instantaneous between me and the house next door but it still doesn't confer to me what is going on behind closed doors. Being able to detect something as it happens doesn't mean you would be aware of everything that is happening.

 

The "cosmic perspective" I have been presenting does not claim to confer omniscience. It is a presentation appropriate to "the philosophy of science" that an overview of the cosmos as a whole, as percieved from the transcendental state of "omnipresent consciousness" would (does, for mystics in cosmic consciousness!) see the cosmos as it is now rather than limited to what local perspectives can see within the relative limitation of the speed of light as the conveyance of images.

 

Again Modest's replies are all based on his firm belief that "It is all relative" and that time is a medium through which an observer can travel depending on velocity variables.

 

This is false from the ontological basis of "what time is" which I have presented in my thread.

Again, from cosmic perspective it is, presently now everywhere regardless of who can see what and when from local perspective, depending of course on lightspeed. And "elapsed time" is simply the recognition of event duration, as per the usual conventions... that an earth revolution requires 24 "hours," etc., and that it "takes time" for light to travel from one place to another, though it is all "happening now" everywhere.

 

Michael

[Moontanman]

Ok, I am trying to divide this up into chunks I can understand, lets say for now that we are not talking about sending message to anyone. We are just able to detect something that has happened , say a nova, the instant it happens. We are not telling anyone else about the nova or anything like that. Lets say it's a natural phenomenon that occurs when some high energy occurrence happens and we are able to detect it the instant it happens no matter where the phenomenon is. No relativistic motion is involved.

[modest]

Ok, I am trying to divide this up into chunks I can understand, lets say for now that we are not talking about sending message to anyone. We are just able to detect something that has happened , say a nova, the instant it happens. We are not telling anyone else about the nova or anything like that. Lets say it's a natural phenomenon that occurs when some high energy occurrence happens and we are able to detect it the instant it happens no matter where the phenomenon is. No relativistic motion is involved.

 

The difficulty is that "the instant it happens" needs to be rigorously defined. In relativity, two events may be instantaneous for one observer while they are not instantaneous for another observer who is in the exact same spot as the first observer. This is a complication to the idea of 'instant viewing'.

 

Consistent with the Andromeda paradox I linked above, if someone could 'see' all the events happening in their present instant then they would have a certain view of the universe but as soon as they start moving (even a little bit), that view will change. Your example above has somebody viewing a nova the instant it happens. We might say the person viewing the nova is driving a car in the direction of the nova when he sees it happen.

 

He looks up and notices the flash with his instant vision, so he decides to stop the car to get out and get a better look at whats going on. But, as the person stops the car he notices (with his instant vision) that the nova gets dimmer and disappears. When he gets out of the car he sees the star where the nova will be. The nova hasn't happened yet. Stopping the car and adjusting the motion of the viewer has shifted his perception of the universe's "right now".

 

The guy that saw the nova might tell somebody on the street corner that there's about to be a nova and then, indeed, there is one. So, this is a somewhat odd situation and not easily reconciled with logic. How could two people in exactly the same spot see two distinctly different things with their instant vision? One would see a star while the other sees a nova. The typical resolution to this "paradox" is that information cannot be sent faster than c making the nova impossible to observe until its photons or neutrinos or whatever other particles reach the observer.

 

To examine the effects of this kind of instant vision, it's most helpful to consider situations in the form of Minkowski spacetime diagrams.

Here there are two inertial observers (green and blue) and a nova (red). Time is pointing up on the diagram. As things move upward in the diagram along their path they are moving forward in time. Space (a single dimension) is left and right on the diagram. As things move left or right on the diagram they are moving through a single dimension of space.

 

Green is at rest. It is moving through time upward but not through space left and right. Blue is moving relative to our coordinate system. It is moving away from green and toward red (the nova). As time moves forward (as things move up on the diagram) blue gets further away from green (the other observer) and gets closer to the nova. The star/nova is at rest relative to the green observer—moving up on the diagram, the distance between them remains the same.

 

This is the situation then... A couple of observers are some distance from a star when it goes nova. The red dot is the nova. Light is emitted at the speed of light from the nova and intersects our observers. Light is the yellow line and it intersects the solid green and blue lines where they are predicted to observe the nova—toward the top of the diagram.

 

But, what if the green and blue observers could see distant things happen instantly. Those are the blue and green dotted lines. At the point a, blue and green are at the same point in space and time (they are touching), albeit they are moving relative to one another. At that moment they both look at everything in their "right now" along their dotted lines. Blue sees a nova remnant while green sees the star before the nova happened. Their spatial axes are not parallel so they have different instantaneous views of the universe around them.

 

The way blue's time axis and space axis are rotated is a visual representation of the Lorentz transformations and its what relativity is all about. I realize that if you're new to looking at spacetime diagrams then this might seem to confuse things more than clarify them, but, trust me, if you become comfortable with the diagram it will become a way of thinking about the situation which makes things very intuitive.

 

~modest

[Moontanman]

I think this may be the answer to my question: if the speed of light is the limit and relativity is real then there is no preferred frame of reference. But if there was instant communication there would have to be a preferred frame for reference the "same instant everywhere" this would invalidate the time paradox. The paradox occurs only if there is no time frame shared by all observers. I think that if there was an instant communication the time frame would not be relative and would be shared by all observers. What causes the paradox is the assumption of no preferred time frame and a preferred time frame. One invalidates the other. If I'm on the right track then it asks yet another question i won't ask until we get this idea right.

 

I also keep seeing the difference between the two observations being caused by one being closer to the nova than the other, but this is not true? Right?

[modest]

I think that if there was an instant communication the time frame would not be relative and would be shared by all observers.

I know of no physics that makes this so. If it were true, then the Lorentz transformations and special relativity would necessarily be wrong. That said, we're looking at a hypothetical that breaks the known laws of the universe as a matter of course, so who's to say one flavor of illogical conclusion is any better than any other :shrug:

 

I also keep seeing the difference between the two observations being caused by one being closer to the nova than the other, but this is not true? Right?

 

Correct, not true, I've carefully kept the two observers collocated (touching) when they make the observation.

 

~modest

[Moontanman]

I do not have the math skills to understand those links, can you give me a real world example of these effects?

[modest]

A real-world example of special relativity? Well... remember the color of gold...

 

~modest

[Moontanman]

Is that a real world example of the Lorentz transformations?

[modest]

Is that a real world example of the Lorentz transformations?

 

Yes, yup, absolutely, no doubt.

 

If gold is silver then we can throw out the Lorentz transformations because they're broken and don't work worth a darn. If gold is, on the other hand, gold, then we're stuck with 'em 'till somebody comes up with something better.

 

Allowing me to wax philosophical for a sec... an example of special relativity (and the lorentz transformations) presents itself any time something moves relative to something else. "relativistic effects" is not the same as "relativity". "Relativity" is any and all movement relative to something else (at any speed).

 

~modest