FTL (Faster Than Light) communications?

--- Not if the measurement is done correctly. Consider:

+-->COM PATH 1-->[EDGE DETECTOR]COM PATH 2-->[FIXED DELAY]--[EDGE DETECTOR]--+

Set up the system so the pulse generator is continuously putting out pulses of a convenient width and PRF, and arrange the fixed delay time so that with the scope trigger source set to A and the horizontal speed set so that no more than one pulse is visible, the rising edge of the received pulse will be seen at some convenient point to the right of the start of the sweep. Now, if a working SSD is inserted into COM path 1,:

+-->COM PATH 1-->[SSD]--[EDGE DETECTOR]COM PATH 2-->[FIXED DELAY]--[EDGE DETECTOR]--+

the propagation time through COM path 1, by the pulse used to trigger the scope, will be decreased and the rising edge of the pulse on the B input will be seen to move to the right of the position it occupied on the display when no SSD was fitted.

Of course, if long COM paths were desired, (say to the moon and back) transponders could be installed on the moon at opposite points on the face it always points at us and the experiment performed that way. Matter of fact, I think that ESP is superluminal and that's part of an experiment which could be performed to determine whether it exists and, if it does, how fast it goes. Wanna hear about it?

-- John Fields

I think I read something in a quantum mechanics book, article etc. that each photon in light has a linked twin, what is done to one happens to the other. So if you could somehow capture the twins and separate them would allow signals to be applied to one and received from the other.

Now how would you capture and hold a photon.

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http://physicsweb.org/article/news/8/6/18

In article , John Fields wrote: [....]

[... ascii art snipped ...]

How far away is the scope? Who's looking at it?

How do we know that the signal on the scope isn't just the result of crosstalk from the input side of the experiment to the output?

How can we prove that the display on the scope really became valid when it claims it did? IE: Could we have a semi-fed cat situation. Since the effort here is to prove something about quantum physics, you can't just assume the current theory is right because that leads to circular logic. You've got to use some really bullet proof logic to prove FTL.

--
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kensmith@rahul.net   forging knowledge

--- Why should either of those matter? All the scope is doing is "recording" the time between two events, one _known_ to occur before the other, and the looker is merely observing whether the leading edge of a repeating pulse moves in a certain direction or not. Why it may or not is unimportant to the observer, who only cares _if_ it does.

---

--- We know what we're doing and we're smart enough to know how to set up our equipment properly.

---

--- We assume the current theory is right, so far, because it has never been disproved (well, except for photon entanglement) and then we carry on with our carefully thought out and executed experiment to determine whether our SSD really works. There's nothing magic about it, if it takes a certain amount of time for a pulse to go from point A to point B and you can, somehow, shorten that time without altering the transmission medium, then you've exceeded C for that medium.

Check out Cherenkov radiation. C gets violated all the time.

-- John Fields

[...]

This is the part of my point you didn't get. To pick a single example assume you are doing an experiment where the results could prove either (A) FTL or a (B) mistake on page 7 in the big book on QM. If you don't rule out the flaw in QM the best your experiment can do is prove either (A) or (B) must be true. It can't prove (A)

You have to prove that you have really shortened the time and not created some sort of semi-fed cat situation.

I don't think so C is the speed of light in free space. Cherenkov happens when something's speed exceeds the speed of light within the medium. It all happens at less than C.

--
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kensmith@rahul.net   forging knowledge

--
Nothing can _prove_ A, but the very fact that the result of the
experiment yielded the possibility that A _might_ be true certainly is
a starting point for more rigorous study of the purported SSD.  And QM

I do. Nothing moves as a result of quantum entanglement, and it can't be used for FTL communication.

John

In article , John Fields wrote: [...]

In this case the scope or to be more exact parts of it would be the semi-fed cat.

FTL communications implies that information got to the scope before a beam of light could have. You do not know the true state of the scope until you look at it. This is when you make the "measurement" of the state of the scope.

The trouble is that you actually make that measurement after light could have gotten there. You assume that things are working like they always do and that the scope doesn't suddenly change its story about the past. This is reasonable under the current view of QM.

FTL communications, however, can be troublesome for the current view. The current view doesn't rule out the semi-fed cat. The semi-fed cat is just too weird and, it was discovered, not needed to make the predictions come out right. If it is discovered that somehow the scope seems to be changing its story, a fault in QM and not the FTL communications is proven.

If matters a whole bunch. "C" is the top speed of communications in the universe. It just happens that light goes that fast. Other types of communication also have "C" as an upper limit. "c" on the otherhand depends on the medium. It may even be that somethings still work at "C" through the medium that slows light.

[...]

I find FTL communications about as troubling as semi-fed cats. Entanglement may or may not provide a means to do FTL. So far, no-one I know of have communicated any information via it. If they do, I will find Entanglement troubling.

--
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kensmith@rahul.net   forging knowledge

--- I don't see why when the scope gets its trigger matters. Think about the experiment this way:

The two fastest runners on earth, Racer A and Racer B, are equally matched, consistent, and always run the same distance in the same time. Now, for the sake of an experiment, Racer B is forced to wear running shoes which weigh one ounce more than Racer A's. As a result of that, Racer A crosses the finish line before Racer B, starting a clock which stops when Racer B crosses the finish line, and the clock _always_ reads 100ms when it stops, no matter how many races are run.

Now, to determine whether it's possible for Runner A to run faster than his "limit", he's given a substantial hit of speed and the race run again. This time, at the end of the race, the clock reads one second. Knowing that good old, dependable, Runner B ran the race as he always had before leads to the conclusion that Runner A ran faster than he normally would have.

Notice that the clock didn't care about how fast Runner A was going or how long it took it to get to the finish line, all it did was record the difference in time it took for the two runners to cross the finish line.

But, just to keep everybody happy, and since we don't really know how the speed is going to affect Runner A, what we do is set up a concurrently running second experiment which measures the time it takes for Racer B to run the race and use that to make sure that the larger than normal time difference at the finish line wasn't due to Runner B going more slowly than he had before. We could, of course, also attempt to directly measure the time it took Runner A to run the race, but we save that for a later experiment since we can derive it from the results of the two we ran.

---

--- The scope doesn't care about the past; all it's doing is getting triggered by an event.

---

--- We don't know that for sure, it's just that _we_ can't seem to find anything going faster because _we're_ bound, so far, by what we don't know.

---

--- Only as the limit allowed in a vacuum, and it varies just like everything else does depending on the density of the medium it's traversing.

---

--- _Any_ types of communication, so far.

---

--- Assuming that things which work at C can't go slower than C, then it seems reasonable to assume that the "slowing" isn't a slowing at all, but the extra time required for the thing to bounce around in the medium before it finally comes out.

---

--- I'd find it exhilarating!

Just imagine, a crack in the door that's been closed to us since the beginning of time!

Ultimately, the elimination of one of the barriers that keeps us from going to the stars...

-- John Fields

--- Maybe not yet, but check out:

and note, in particular:

"To demonstrate open-destination teleportation, Pan and co-workers first teleported the unknown quantum state of a single photon onto a superposition of three photons. They were then able to read out this teleported state at any one of the three photons by performing a measurement on the other two photons."

-- John Fields

I read in sci.electronics.design that John Fields wrote (in ) about 'FTL (Faster Than Light) communications?', on Sat, 14 Aug 2004:

THREE photons? Is this the birth of the TRI-corder?

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

But none of this implies useful signal FTL communication, as you seem to be suggesting that by the "Maybe not yet, but check out".

Its an accepted given by all pro physicists that entanglement can not be used to send FTL signals. Its simply not debatable under QM, unless QM is wrong. Its a basic result proved based on the postulates of QM. There is no escape from this mathematical proof, unless QM is wrong. So, why this FTL stuff keeps getting churned out is beyond me. Its simply not allowed under accepted QM. Period.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

I read in sci.electronics.design that Kevin Aylward wrote (in ) about 'FTL (Faster Than Light) communications?', on Sat, 14 Aug 2004:

Like everything else in science, QM is wrong. We just haven't found anything more correct yet, and when we do, that will be wrong as well.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

--- I'm suggesting nothing of the kind. The "Maybe not yet" part should have made that clear, since to imply otherwise I would have written something like "Oh, yeah? then check out..."

The "Maybe not yet" part was meant to imply that how to do FTL _will_ eventually come to light (groannn :^), and the "but check out" part was just a pointer to another brick coming out of the wall.

---

--- Yes, and to pro clerics neither was anything but a terracentric universe allowed up until a very few years ago.

It's probably a good thing that not _everyone_ accepts the edicts of current authority as immutable truth, since there's still a lot out there we don't know anything about, and looking for it in the face of naysayers and, sometimes finding it, is fun.

-- John Fields

I have, but nobody seems to want it.

Cheers! Rich

[... using runner instead of photons ..]

You've missed the whole point of my argument. Switching to human runners doesn't help. Lets try this:

You have some electronics in one room with a push button on it. In another room you have two devices that display numbers. You believe that the numbers these devices display are the time since Jan 1, 1980 until a pulse arrives at each input.

You press the button and go look in the other room. When you get there they show a difference of 1 second. From this you would conclude that the travel time down the two paths is really one secon different.

You believe that your measuring method is correct. You also believe that this 1 second difference is proof of FTL.

Lets further assume that your currently accepted theory of physics say both that the equipment is indeed measuring the speed correctly and that FLT is imposible. You have just proven that this theory is wrong.

Lets say, there is another theory of physics which states that the entire contents of that other room does not exist unless you are looking at it. Under this theory, the equipment and the measurement even the windows and drapes and potted plants wink in and out of existance. This theory is so weird you've rejected because (A) its weird (B) you have another theory that worked perfectly.

Now you are in a bind. The theory you have been using is now proven to be false and the truely weird one may be all you've got. Under this truely weird theory, there was no information in the room at all until you opened the door. In this theory FTL is still imposible.

I agree we can't really be sure its right but that is what I mean by "C".

Exactly "C" is an upper limit.

I agree

It could also be that light never really travels at "C". It may always travel at "c".

Warping through space would be nice. Some of the other things it implies would be less so, I think.

--
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kensmith@rahul.net   forging knowledge

Essentially, yes, but technically implemented differently.

In fact, its the other way round photons *always* travel at "C", i.e. the 3e8 max speed in vacuume. Atoms consist of 99.99etc% of vacuume. Photons can't slow down, ever. The speed of light in a medium is an

*apparent* speed. Atomic electrons absorb photons, go to a hifger energy state, then after a delay, emit a new photon. It is this delay that makes for an effective slower velocity. You know its the whole exited electrons is an atom bit, Balmer series and all that jazz.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

Ok.

My point being that, sure, in a bigger scheme of things QM might be wrong, but non of these researchers/experiments are actually claiming that what they are doing violates QM in any way to date. They are just presenting some of the strange aspects of QM as it stands.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.