Instantaneous Communications plus Time Dilation Equals ???

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Well' date=' you see, there's this guy named Einstein who had a few thoughts on that very subject....[/quote']

 

OK, so how does the light do both? I don't mean appear to do one or the other depending on where you're standing, I mean actually do both?

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

The two aren't mutually exclusive. It seems like they should be, but they're not. The universe allows "they hit at the same time" and "they hit sequentially" to both exist.

 

Luckily the universe is kind enough to throw time dilation into the mix, so even though simultaneity doesn't mean what we think it should, causality is not violated. You can't exploit the lack of simultaneity to, say, see what's going to happen before it happens.

 

Until you throw wormholes into the mix. Then you get the freak show we're discussing in this thread.

[dmjalund]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

2 events cannot be determined to be absolutely simultaneous, they can be determined to be:

1) the light from event A could theoretically reach event B - event A is therefore in event B's past

2) the light from event B could theoretically reach event B - event A is therefore in event B's future

1) light from one event cannot reach the other event - the relationship between the events are called 'space-like' and can be seen to be simultaneous to SOME observers (depending on the Observers' speed)

[Zeropoint]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Yep, as confusing as it is, "at the same time" is NOT an absolute for events separated in space. Confusing, but true.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

None of which changes the fact that the train is either moving in relationship to the photons from the flash, or it isn't. It cannot be both.

 

If it is, then the photons reach the back before they reach the front. If it is not, then the photons reach both ends at the same time. It doesn't matter what the guy on the train sees, or the guy on the platform sees.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Light is a freaky thing. It moves faster than anything else can. It behaves according to observations that haven't been made yet. It always travels at the same speed to any observer, regardless of anything else going on.

 

That last one is the key here. It really does matter who's watching. There's no absolute frame of reference. That's why it's called relativity.

 

I'm not sure how many other ways we can phrase this. If you want crunchier explanations, there are plenty of books that lay out the math as detailed as you want to get. It may seem less crazy with graphical aids we don't have in this text environment.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

I'm not suggesting an absolute frame of reference.

 

It's just that:

 

A) two mutually exclusive things cannot be true, and

if a tree falls in the forest and no one is there, it still makes the same noise -- the observer is unnecessary to the continuance of reality.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

The point is, they're not mutually exclusive. Consider the headlight-on-a-train analogy. I'm standing on the platform as the train goes by. It switches on its headlight. What I see is the beam of light moving forward at c. I also see the train moving in the same direction at a lower speed v. To me, the beam of light is pulling away from the train at a speed of c-v.

 

The train engineer looks out his window when he switches on the headlight. What he sees is the beam of light moving away at c. Not c-v, but c because the speed of light is constant in all frames of reference.

 

Is the train moving in relation to the photons?

 

When the engineer switches on the headlight, he also fires a rubber science rocket-camera mounted on the front of the train. The camera travels at a speed infintesimally close to c. From the platform, I see the beam of light moving away from the projectile at some infintesimal speed. The camera sees the beam of light moving away at c. Is the camera moving in relation to the photons?

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

So there's a difference between perception and reality, then, or something.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

That's the weird thing. It's not an optical illusion. It is reality. That's where the time dilation comes from. The reason the engineer sees the light beam moving away from the train faster than I do is because time is moving slower for the engineer. Time is moving much slower for the rocket camera, due to its speed.

 

(Incidentally we tend to simplify the thought experiments by anthropomorphizing them with humans, cameras, etc. But when I say "observer," I don't mean there has to be some intelligence or perception mechanism. Anything that has any kind of contact with the object can be called an "observer.")

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

That's the weird thing. It's not an optical illusion. It is reality. That's where the time dilation comes from. The reason the engineer sees the light beam moving away from the train faster than I do is because time is moving slower for the engineer. Time is moving much slower for the rocket camera, due to its speed.

 

(Incidentally we tend to simplify the thought experiments by anthropomorphizing them with humans, cameras, etc. But when I say "observer," I don't mean there has to be some intelligence or perception mechanism. Anything that has any kind of contact with the object can be called an "observer.")

 

Which I admit keeps tripping me up; it's one of those unfortunate terms of art.

 

 

But I think I'm just going to drop it. That there can be two different realities of the same event is just too impossible to take seriously.

[Nyrath]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

But I think I'm just going to drop it. That there can be two different realities of the same event is just too impossible to take seriously.

Well, not to put too fine a point on it, but engineers who design high tech equipment have to take it seriously.

If you do not take into account Einstein's relativity, things like GPS devices will not work. They have to make corrections for relativistic effects.

 

From a practical standpoint, it does not matter if it seems to be impossible, it is just the way the universe works.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Well, not to put too fine a point on it, but engineers who design high tech equipment have to take it seriously.

If you do not take into account Einstein's relativity, things like GPS devices will not work. They have to make corrections for relativistic effects.

 

From a practical standpoint, it does not matter if it seems to be impossible, it is just the way the universe works.

 

Experimental and engineering confirmation of relativity, sure.

 

Two different actual realities of the same event? Not a chance.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Experimental and engineering confirmation of relativity, sure.

 

Two different actual realities of the same event? Not a chance.

Think of it as akin to the Doppler effect. If I'm on the train, the pitch of the horn is constant. If I'm on the platform, the pitch of the horn changes as it passes.

 

Question: What's the pitch of the horn?

Answer: It depends on your frame of reference.

 

Is that two different actual realities of the same event? No, it's one reality as it affects two different frames of reference. The "reality" is the horn vibrates the air at a certain frequency in its reference frame. Its effect changes in different reference frames.

 

Same with the simultaneity scenario. The reality is "two beams of light are emitted in opposite directions in the train car." The effect changes in different reference frames.

 

Anyway.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Think of it as akin to the Doppler effect. If I'm on the train, the pitch of the horn is constant. If I'm on the platform, the pitch of the horn changes as it passes.

 

Question: What's the pitch of the horn?

Answer: It depends on your frame of reference.

 

Is that two different actual realities of the same event? No, it's one reality as it affects two different frames of reference. The "reality" is the horn vibrates the air at a certain frequency in its reference frame. Its effect changes in different reference frames.

 

Same with the simultaneity scenario. The reality is "two beams of light are emitted in opposite directions in the train car." The effect changes in different reference frames.

 

Anyway.

 

The Doppler effect is an actual change in the frequency of the sound or other wave.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

I surrender. At this point, reviewing the thread, I have to conclude that you understand what we're saying, but you don't want to accept it. That's fine. Let me just say that special relativity is not a matter of perception or personal philosophy or even common sense. It's a scientific framework that has been challenged, and confirmed, over the course of a hundred years by lots of very smart people who are fully aware of how crazy it sounds. I urge you to research it further using whatever scientific sources you trust. Hopefully it'll click one day, because it's pretty cool, mind-expanding stuff.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

I surrender. At this point' date=' reviewing the thread, I have to conclude that you understand what we're saying, but you don't want to accept it. That's fine. Let me just say that special relativity is not a matter of perception or personal philosophy or even common sense. It's a scientific framework that has been challenged, and confirmed, over the course of a hundred years by lots of very smart people who are fully aware of how crazy it sounds. I urge you to research it further using whatever scientific sources you trust. Hopefully it'll click one day, because it's pretty cool, mind-expanding stuff.[/quote']

 

As far as I'm concerned, there has to be a solution that doesn't involve mutliple realities of the same event. I had no problem with relativity as a concept until I read the train example, and then the whole thing fell apart for me.

[BobGreenwade]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Getting back to the original question (or at least something related to it):

I get the whole "time passes more slowly for Unit B". I really do.

 

What I don't get is how that makes Unit B in 2150 connect to Unit A's past, not Unit A in 2150.

The combination of relativity plus the wormhole is what makes unit B in 2150 remain in connected to Unit A in 2051. One year passes for Unit B, and therefore one year passes for the wormhole. The wormhole keeps the two units synchronized in subjective time, as experienced through the wormhole. Thus, as one year of subjective passes for Unit B while 100 years pass for Unit B (and the general, "objective" time reference), the wormhole only advances one year, including the end at Unit A.

 

They key to understanding it is accepting that, in relativity, subjective time makes a real difference (as it demonstrably does for the GPS network).

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Setting aside wormholes, I'm still curious about the interaction between time dilation and entangled particles. I know they've experimentally shown that entanglement transmits state FTL (granted the info isn't accessible FTL). Shouldn't it be possible to test the effects of multiple entanglement state changes under relativistic conditions?

 

I'm not clear on how you verify state transferred via entanglement. Can you keep tweaking the same entangled pair over and over? Could you tweak one particle at a given frequency, move the other particle at relativistic speed, check it at the same frequency (time-dilated) and see if the results correlate?

 

Or does that even have meaning with entanglement? I know QM doesn't much factor time into its equations. That's why I suspect, unlike a wormhole, an entanglement device wouldn't lock the two particles into a single frame of reference.

[Nyrath]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

The Doppler effect is an actual change in the frequency of the sound or other wave.

Ummmm, I'm confused. The person on the train hears one frequency, the person on the platform hears a different frequency. So what frequency is it? How can it be two different frequencies simultaneously?

[BobGreenwade]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

That's why I suspect' date=' unlike a wormhole, an entanglement device wouldn't lock the two particles into a single frame of reference.[/quote']I'm not aware of any actual, trained physicist (which, of course, I'm not) making any conjecture on how time dilation or any other aspect of relativity would affect quantum entanglement. The best that I can figure, based on recent and extensive reading, is that whatever affects one entangled particle equally affects all others -- which leads to effectively the same conclusion you reached, albeit for a different reason.

 

I do know that there is no known practical way, even in conjecture, to communicate data via quantum entanglement. Dozens of thought experiments have been designed, only to be shot down on careful examination. I don't know that even the level of time dilation at the far end can be measured, at least using any equipment we'd have around today. I personally think that something will eventually develop, but not in the near future and not based on the principles of physics as we now know them -- and that's just my own speculation.

[austenandrews]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

I do know that there is no known practical way' date=' even in conjecture, to communicate data via quantum entanglement. Dozens of thought experiments have been designed, only to be shot down on careful examination. I don't know that even the level of time dilation at the far end can be measured, at least using any equipment we'd have around today.[/quote']

You can't communicate exclusively through entanglement, but as I understand it, you can send data that's retrievable through other means. So even though you wouldn't know what your frequency readings meant until you received the "key" through conventional means, you could still do the measurements. I just don't know if that kind of information would have meaning in an entanglement context.

 

I personally think that something will eventually develop, but not in the near future and not based on the principles of physics as we now know them -- and that's just my own speculation.

Speculation is fun. This thread makes me want to catch up on the current state of this stuff.

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Ummmm' date=' I'm confused. The person on the train hears one frequency, the person on the platform hears a different frequency. So what frequency is it? How can it be two different frequencies simultaneously?[/quote']

 

I suspect you know the answer, and that the Doppler effect is not the same class of phenomenon as what's being suggested in the "train example" for light.

 

(For those who don't know, the person on the train doesn't experience the Doppler effect that the person on the platform does because he's moving with the train and the horn.)

[Old Man]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Actually it's exactly the same phenomenon. If we were discussing light, then the viewers would perceive light of different colors (assuming a really fast train). What color is the light in "reality"?

[Kristopher]

Re: Instantaneous Communications plus Time Dilation Equals ???

 

Actually it's exactly the same phenomenon. If we were discussing light' date=' then the viewers would perceive light of different colors (assuming a really fast train). What color is the light in "reality"?[/quote']

 

If you'd read the linked Wiki article, you'd see that we're not talking about Doppler shift in light.