Quantum entaglement as propulsion - Interstellar spaceflight possible?

Dook · 2004-08-13 01:03:28

...circadian rhythms and I suspect that there would be some important issues on how these react to microgravity, ambient light, activity levels, etc. as we get away from Earth. Some of this MUST have already been investigated.
http://www.ortho.lsumc.edu/Faculty/Mari … html]Frank Brown as a founding investigator regarding Circadian rhythms. And http://www.space.com/scienceastronomy/v … 05-2.html] Joe Miller for a martian 'radioactivity footprint'.

BTW I'm 43 but I suppose one could say I am a student with a hobby studying the organisation of alphabets, number, time and shape. I retired from a 20 year career with Londons Tube Network, London Underground due to illness. I have a hobby trying to find what surrounds nothing on the smallest scale and its primary applications.

Ant

Guess I'm a little late in responding to your question but the body knows how to age by cell division. Each time a cell divides the DNA transfers from the original cell to the new cell and the DNA, in effect, gets narrower. The bars (telemeres) connecting the two strands of DNA shorten with each division.

Euler · 2004-08-13 01:42:08

So I guess the question is, are the changes that are the result of observation the same as the changes due to intentional manipulation of the entangled particle? If not, then there is no conceptual problem with something polling the entangled particles periodically to see if they have changed. If they are the same, then it would seem that extracting the information might be complex.
Another question. If an entangled particle is manipulated, does it then "disentangle" from its partner or is the entanglement maintained? If the latter, and if the operations needed to "read" the information cause spin changes in the entangled particles, then the sender could know immediately if her message had been read.

I am not completely sure, but I am beginning to think that the entangled particles can't be manipulated, or at least they can't be without disentangling them. If that is indeed the case, then FTL communication is certainly not possible and we would not ordinarily think that anything unusual is happening. It is just the quantum mechanical idea that by measuring something that you are forcing it to choose a state that makes it seem weird.

This is one of the hardest parts for me. Whenever I read about quantum mechanics, the experimenter is always actively looking for something and doing something to the particles. Does this imply that in the quantum world, you can't simply be sitting there looking at your instruments and something happens serendipitously? For example, when a particle's spin is changed from "up" to "down" is that all that happens? Is energy absorbed or released? And if energy, is, for example, released, can't it be picked up by passive detectors that are not "looking for" it but simply put in a likely place to be irradiated by it.

I think that the different spin states have the same amount of energy. As I said above, I currently don't think that the particles ever actually change from "up" to "down" at all, the just change from "undecided" to "up" or "down".

we must be dealing with semantics about the meaning of "transferred". Since, if one particle's spin is determined to be "up", it's partner's is always "down" it looks like a NOT gate to me.
I don't know about "transfer" between particles, but somehow in the experiment as a whole there is a relation, and therefore a transfer of information, between the states of entangled particles and the rest of the experimental situation or else the previous experiments could not have been successfully performed and it would be absurd to talk about "quantum computing". Yet granting agencies seem to be taking this seriously.

Even if "transfer" of information only appears due to semantics, this could still have some useful applications. One that I have heard about is quantum cryptography: you have two people that each have a set of entangled particles. One person uses his set as a "one time pad" to encrypt a message, and then the other person uses his set to decrypt the message. Assuming the states of the particles are random (and I think that they are) then the system would be theoretically unbreakable. In addition, you could probably also set it up so that it is impossible for anyone to make a duplicate decrypting key, as an additional security measure.

Is this true for ALL events which appear to be simultaneous in our own reference frame? Or is the "universe" composed only of that subset of events which never appear to be going backwards in time regardless of the reference frame?

In relativity, space-time has three regions. There is a light cone going into the future which contains everything that can be influenced by an event with light speed communications. This is the absolute future. There is also a light cone going into the past, which contains everything that could have influenced the event. This is the absolute past. Everything else is ambiguous, and is past in some reference frames, simultaneous in others, and future in the rest. So yes, ALL events that are simultaneous in our reference frame will not be simultaneous in most other reference frames (assuming that the events do not occur in the same place).

ant of stargrail · 2004-08-13 03:54:41

I think that the different spin states have the same amount of energy. As I said above, I currently don't think that the particles ever actually change from "up" to "down" at all, the just change from "undecided" to "up" or "down".

Is not "up" and "down" relative to the observer? An analog clock has a clockwise motion when viewed from the face. an anticlockwise motion when viewed from behind.

I understand that science is trying to identify which spin a hidden paricle has, so it's on it's way towards cracking the Heisenburg uncertainty principle, or the fictional Star Trek transporters. Once someone has identified the spin this can be commumicated and set.

Everything else is ambiguous

But history is relative and written by the victors, it depends on what one is told/read/experienced.

http://www.stargrail.co.uk]Ant

Morris · 2004-08-13 21:11:33

I understand that science is trying to identify which spin a hidden paricle has, so it's on it's way towards cracking the Heisenburg uncertainty principle, or the fictional Star Trek transporters. Once someone has identified the spin this can be commumicated and set.
Everything else is ambiguous
But history is relative and written by the victors, it depends on what one is told/read/experienced.

http://www.stargrail.co.uk]Ant

Is not "up" and "down" relative to the observer? An analog clock has a clockwise motion when viewed from the face. an anticlockwise motion when viewed from behind.

I think they are just terms for two possible states described by the system math. If so, the math would provide the reference frame.

ant of stargrail · 2004-08-14 06:09:40

I think they are just terms for two possible states described by the system math. If so, the math would provide the reference frame.

The math I believe comes from shape.

In the 3 in 1 shape pictured earlier, the 3#3#3 frame cube is composed of two shapes.

Each of these shapes has a framework of 8 tetrahedrons. The 8 tetrahedrons are linked at the corners and when they are spun, each shape appears to turn into both shapes.

One shape is the frame of a centred cubeoctohedron the other is a stellated octohedron. When each shape is spun is gives the appearance of 16 interlocking tetrahedrons, one enmeshed with the other.

This must be an example of quantum entanglement on the smallest level.

http://www.stargrail.co.uk]Ant

SBird · 2004-08-14 18:12:36

Thanks for making us aware of the Everett interpretation. How would this interpretation explain the results of those experiments in "quantum teleportation" which have already been done and have been determined to be valid by replication?

But by looking at them you can predict with complete accuracy what the spin of the entangled "partner" particle must be? And, if you change the spin of a particle, and actually observe it's new spin, then you can also predict with perfect accuracy what the spin state of it's entangled partner must be?
If the above statements are both true, then we must be dealing with semantics about the meaning of "transferred". Since, if one particle's spin is determined to be "up", it's partner's is always "down" it looks like a NOT gate to me.
I don't know about "transfer" between particles, but somehow in the experiment as a whole there is a relation, and therefore a transfer of information, between the states of entangled particles and the rest of the experimental situation or else the previous experiments could not have been successfully performed and it would be absurd to talk about "quantum computing". Yet granting agencies seem to be taking this seriously.

Whew, now I'm really going round and round. I thought that the basis of entangled relations between particles was spin states. Are different spin states at different energy levels? Or are spin states just examples of the properties which can be involved in entanglement?

The Everett interpretation, AFAIK, has been entirely consistent with all observations of quantum events. Basically, it's just as successful as the Copenhagen interpretation and suffers far less from some of the logical inconsistencies and paradoxes. The only big argument against the Everett model is that it calls for the constant generation of new universes. However, this objection (which is suprisingly common even among physicists) is false as the actual Everett model doesn't call for the generation of parallel univeses. Instead, it simply posits that the quantum wave functions never collapse.

Changing the spin of an entangled particle after they are seperated has NO effect upon its entangled twin. What you've done is taken one entangled particled and interacted its spin with another particle's spin, changing it. If one takes the spin of the particle used to change the spin and knows the spin transfer dynamics of the interaction, you can deduce the spin of the entangled partner. Basically, if you had two coins that are both heads up and then flip one of them over, you don't change the fact that the other coin is still heads up. However, by knowing that the coin you have has been flipped, you know that the other is heads up and not tails.

Quantum conputing is an entirely different thing, although related. Basically, before the wave function collapse posited by the standard Copenhagen interpretation, a quantum particle explores all possible solutions to its wavefunction. By carefully setting up the interaction of different quantum objects, you can make a computer that can work on many aspects of a problem simultaneously. The transfer of information in these computers works much as you would expect except for the fact that it occurs in a parallel fashion that is imposible in classical mechanics.

IT's not just the spin state of a particles that's entangled - it's any quantum state that is comehow connected between two particles. It just happens that spin is a value that's easy to measure unambiguously. However, the articles talks about transferring power through the entanglement which is a clear violation of the conservation of mass-energy. Even though it's not as obvious, the transfer of spin or other quantum states through the entanglement link is also just as verboten.

Morris · 2004-08-15 09:04:49

Changing the spin of an entangled particle after they are seperated has NO effect upon its entangled twin. What you've done is taken one entangled particled and interacted its spin with another particle's spin, changing it. If one takes the spin of the particle used to change the spin and knows the spin transfer dynamics of the interaction, you can deduce the spin of the entangled partner. Basically, if you had two coins that are both heads up and then flip one of them over, you don't change the fact that the other coin is still heads up. However, by knowing that the coin you have has been flipped, you know that the other is heads up and not tails.

Thanks for the coin analogy! I now see how you can have information about the state of a distant particle though no information has been transferred (at least in the usual sense of the meaning of the word "transfer").

Basically, before the wave function collapse posited by the standard Copenhagen interpretation, a quantum particle explores all possible solutions to its wavefunction. By carefully setting up the interaction of different quantum objects, you can make a computer that can work on many aspects of a problem simultaneously.

Neat!

IT's not just the spin state of a particles that's entangled - it's any quantum state that is comehow connected between two particles.

Thanks for clarifying this one.

However, the articles talks about transferring power through the entanglement which is a clear violation of the conservation of mass-energy. Even though it's not as obvious, the transfer of spin or other quantum states through the entanglement link is also just as verboten.

Yes, I can see that power transfer would be impossible. What I still need to know is just what is going on in the "quantum teleportation" of laser beams. Maybe Scientific American wrote an article on it.

Again, thank you very much for taking the time to explain these things. It has helped a bunch .

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#26 2004-08-13 01:03:28

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#27 2004-08-13 01:42:08

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#28 2004-08-13 03:54:41

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#29 2004-08-13 21:11:33

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#30 2004-08-14 06:09:40

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#31 2004-08-14 18:12:36

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

#32 2004-08-15 09:04:49

Re: Quantum entaglement as propulsion - Interstellar spaceflight possible?

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