View Full Version : Physics Help
03-25-04, 10:08 AM
I'm currently in the process of writing a paper on Quantum teleportation. I've been reading up on the subject, its pretty cool - the problem is I have absolutely no training in physics. I have basic chemistry and I'm pretty good at differential and integral calc, but other than that, I'm scrooged. I understand the basic principle of everything, but the main thing that confuses me is the concept of EPR entanglement. I'm going to post a clusterfsck of links here for anyone interested. Any help would be really appreciated.
PDF File Dealing with EPR
An early paper published on the subject, its a little technical. (PDF)
HowStuffWorks guide to teleportation (God, I love this site)
If you all turn up any interesting links, please feel free to share. (Especially if the links regard anything like stumbling blocks to the process and/or philosophical implications.) Thanks!
03-25-04, 12:45 PM
Quote:the main thing that confuses me is the concept of EPR entanglement
Imagine a particle decaying. When this particle decays it emits 2 particles. These two emitted particles (p1 and p2)both have a 50% chance of being in a certain state, lets call one state green and the other red. The thing about quantum particles is that they have no definate states before we measure them, so while these particles fly happily through space, we can say they ar eniether red nor green as they may change in flight.
However, if we decide to measure p1 and p2, and most interestingly, if we decide to measure p1 before p2 we see a very strange phenomena. If we measure p1 to be in a green state, then p2 even though it is in an undertermined state and has yet to be measured, must measure as red.
So no matter how far apart the particles are when they are measured, the state of one determines the state of the other.
This is a (very) paraphrased example of the Einstein-Podolsky-Rosen paradox, the first inklings of what has now become the ridiculous theory of quantum teleportation. For the first major work regarding this idea look up John S. Bell around 1964. I'm going straight to hell, just like my momma said.
03-25-04, 01:02 PM
Thanks a bunch, that does make it a little clearer - do we know what causes the phenominon, though?
Quote:ridiculous theory of quantum teleportation
I thought this, too, but it turns out - the theory is not so rediculous:
Quote:In 1998, physicists at the California Institute of Technology (Caltech), along with two European groups, turned the IBM ideas into reality by successfully teleporting a photon, a particle of energy that carries light. The Caltech group was able to read the atomic structure of a photon, send this information across 1 meter (3.28 feet) of coaxial cable and create a replica of the photon. As predicted, the original photon no longer existed once the replica was made.
We'd just need some super heavy-duty computers to arrange the particles and so forth. (Quantum computing, perhaps?)
03-25-04, 03:05 PM
Quote:do we know what causes the phenominon, though?
It's pretty much a natural result of the Heisenberg Uncertaincy Principle, and Quantum Mechanics. Kind of like the phenomenom of planetary orbits being the result of gravity.
The problem here is that while this certainly works in theory, teleporting anything larger than particles would consume to many resources to even consider. I'm pretty sure just a chair has something like a trillion trillion atoms, which i think is like less than our current deficit under Bush but still quite a lot...
I see this eventually being regulated to the same "almost could-a-been innovations" catagory with stuff like cold fusion. I'm going straight to hell, just like my momma said.
03-25-04, 03:23 PM
Yeah, but with the advent of quantum computers, non-binary format, and superposition of code, computing power may very-well reach the point of such calculations.
Desperate plea: Somone please join Xan and I in this discussion. I feel like we're being those two nerds that sit around and discuss how the inventions off of star trek could feasably work. Perhaps philosophy tickles your pickles more... if you were to be teleported and your original body were, would you still have the same soul?
03-25-04, 03:31 PM
The energy required to transport anything of a mass that would matter is completely prohibitive. It's a cool "ooh ahh" thing, but has no practical aplication in the star trek sense.
03-25-04, 03:48 PM
we have plenty of energy - imagine if we were able to convert a penny into pure energy... it sounds all sci-fi and shiz, but it's technically possible.
03-25-04, 04:22 PM
Then try reconstructing it exactly and everything at the same time Misalignment of mere angstroms could be catastrophic with a living organism, especially in say, the brain area. Or, if the head is constructed before the rest of the body, you have to deal with extreme shock and probably blood loss.
It would have to be in a vacuum, right, or else where would the air go when a whole organism is created right there? Either it would become trapped, causing death, or somehow miraculously pushed out of the way. If it is in a vacuum, the lack of pressure would kill it instaneously anyway.
Plus, even if you did create a replica of an organism would it retain its intelligence and psyche?
What if a fly flew into the machine and ended up crossing DNA with you to create a super fly headed man with wings?
03-25-04, 05:05 PM
It would create an overpaid one-trick pony with an 80's haircut and cliche 'smart dude' glasses.
03-25-04, 06:13 PM
Quote:Somone please join Xan and I in this discussion. I feel like we're being those two nerds that sit around and discuss how the inventions off of star trek could feasably work.
No that would be what happened when the CS study group back at university found out I was a physics major.
/shudder I'm going straight to hell, just like my momma said.
03-25-04, 10:07 PM
There is another... kinda of not so known part of "Quantum Teleportation"
When you teleport things through Quantum measures, you send them, and since they each take different times to get there (unless you send em through a Coaxil cable, which onl really demonstrates that they could send light through a cable, hi fiber optics), you dont know which particle is which.
Its like sending 400,000 packets to someone, but not giving them directions on how to put it back together. And you can now see the flaw in this means of 'travel' (at least in todays technology). In order to know the code, its allready been sent by a different means, so the new one is useless
Ive been doin some research on these aspects too, SuperString Theory is something to look at, as it is prolly more plausable than Quantum Teleportation.
03-25-04, 10:39 PM
I've read up on some stuff about super string, but it was all crackpot theory on time travel. Could you link me to the site where you found it applied to teleportation?
That is an interesting hypothesis, I think - but I am a little confused. (I acknowledge that I'm most likely confused because I have grossly misinterpereted what you were saying. Bear with me, they don't teach us good in TN.) It seems to me like you are suggesting we transfer the particles as well as the information. The particles are reassembled in another place after getting the information. So technically, once you have all the info, then you reconstruct it from raw materials.
The whole idea of teleporting people creeps the seamen out of my eurethra though. I only see this @#%$ as feasable for a 3-D fax machine... which would be bitchin. The idea of human teleportation - even if possible - just carries too many naughty philosophical connotations. And another thing... if we were to teleport a person, we'd have their atomic information stored, right? So what's to prevent us from just making a second copy?
03-25-04, 10:50 PM
You couldn't make a copy without a way to reconstruct with perfect detail atom and molecular structure. You'd have to be able to create complex carbon chains and all sorts of stuff perfectly, and know where it all goes exactly. Putting it all together would be hard, and making it all exactly right would be hard too.
Plus, just because you threw a glob of carbon, oxygen and hydrogen together doesn't make it turn to life. If it did, couldn't we make pretty much any life form we want? Just string together a bunch of human/pig/goat/beetle/fish organs and put it in a flesh sack, BAM new species.
03-25-04, 11:09 PM
take out hard and put in impossible
understanding Folding is still in its BABY stages. So no way could we actually reproduce that kind of protein.
Even still, You still need to have the 'key' to reproducing the item on the other side. So you need to have allready have the key travelling there, on a Seperate path than the "Quantum" level.
Which is why I said to read up on Super String theory and Time Travel (in general), rather than Quantum Teleportation, its more feasible (though we wont see either in the next few generations less there are super babies with stephen hawking dna )
Everything I know about Quantum Teleportation I learned through Crichton's book "Timeline".
In other words, it's interesting but I don't feel like taking several college classes or reading Hawkings' work to understand it. However, I have read some stories on Quantum Computing and it sounds badass....
03-26-04, 12:25 AM
Quote: Quote:Somone please join Xan and I in this discussion. I feel like we're being those two nerds that sit around and discuss how the inventions off of star trek could feasably work.
No that would be what happened when the CS study group back at university found out I was a physics major.
Yeah, I feel your pain, man. One of my bio nerd friends and I were sitting at a table in class one day and I had tears in my eye from a problem I had read in my biology book. He asked me what was wrong and I told him the story. A real company invented a diet drug in 1994, the FDA (food and drug administration... not the newgrounds thing with the butt...) let it pass through. It was later repealed because people kept dieing. My voice escalated into a crescendo of laughter as I explained to him that the drug worked by making the inner cristae of the mitochondria permeable to hydrogen. (If you don't get it, I envy you.) We both nearly fell out of our chairs laughing... then we stopped and looked around... Thats one of those moments where you can't help but think, "I will never f*** anyone in this room...ever."
Anyways, back to physics... Timeline is actually what got me interested in this. The more I study it, though... (just for the record, I'm still working on grasping the concept of superstrings) teleportation (of inanimate objects) seems plausible by matter reconstruction... just not in the near future. I think the most plausibility comes with the concepts of wormholes and so forth. I still don't agree with the theory that wormholes will provide time travel, because I don't agree with the theory that time really exists... but then again, time travel always comes down to a semantics argument, so I'll dodge that bullet. Wormholes, however, seem like they might actually have some pretty practical use for interstellar travel.
The real curious thing is the limitations of all these seem to be the age of people. Teleportation could never be instant. It could just be at the speed of electricity, or whatever medium you chose to transfer the information through. So lets say we wanna go way the hell out to alpha centauri, so we open up a wormhole, then use the matter reconstruction theory of teleportation to send the data through a wormhole (we're saying theoretically that we could reconstruct the matter on the other side). Even ducking through a wormhole might still take several light years, so by the time the colonists arrived, the people that sent them would all be long dead and the technology long outdated. The only way we might be able to communicate with our outposts would be using EPR connections to create devices somewhat like ansibles (damn you, Orson Scott Card).
Hmm.. I'm getting into too much theory, I need to write this up in some way shape or fashion. Keep talking, I'm thinking about citing you all as a source in my paper... that is if you don't mind. (Just one of those "interesting theories and discussion" blurbs.)
03-26-04, 01:10 AM
Quote:We'd just need some super heavy-duty computers to arrange the particles and so forth. (Quantum computing, perhaps?)
Well we just need some heavy duty computers, and a @#%$ of energy to arrange atom and we can create our very own humans, or whatevr other object you can think of. In theory building object from scratch is not that hard, but in all practical application, 6e23 is a large number, and bulding a gram of material at a bilion (1e9) atoms per second still takeds 6e14 seconds or around 2 milion years.
You also need to transfer this information somehow. At some point you run into theoretical boundaries with transfer speeds as well. But lets say we can transfer data at 10 million Gigabits per second, and that an atom can be store and 10 bits, you are still looking at 2 years just to transfer the data build 1 gram of material. Ishwar - level 65 Barbarian Rogue - GM smith
03-26-04, 05:23 AM
In a graduate level Quantum physics course we looked into what would be required to teleport the average human.
If you imagine a working quantum computer with the square root reduction in processing time that the parallel states provide and made such a computer out of every single electron in the universe (negating the single electron theory), performing one operation per second per electron, you would still need about a billion years to figure out how to re-arrange a human with any sort of quantum teleportation device.
Now this example took many liberties but needless to say it isn't possible with the current techniques.
If I'm going to Alpha Centauri, why in the world do I need to wake up there with the exact same fingernail molecules and gut fauna?
Transmit the software, I don't care what happens to the meat it runs on.
03-26-04, 08:39 PM
And when I say "a lot of energy" I mean greater than the magnitude of a black hole.
03-26-04, 10:34 PM
Quote:or reading Hawkings' work to understand it
Actually Hawkings "A Brief History of the Universe" is an EXCELLENT read, even for those with just a passing interest in physics... or hell even Sci-Fi. I would also suggest "The God Particle" by Leon Lederman. I'm going straight to hell, just like my momma said.
The God Particle is a very sad book. It was published in 1993, and Lederman was so excited about the Superconducting Supercollider...
03-27-04, 10:02 AM
It's even sadder to drive by the site and see the abandoned houses after reading the book. I was so severly pissed off about that whole debacle. I'm going straight to hell, just like my momma said.
03-27-04, 10:29 AM
Have you guys seen PBS's The Elegant Universe .
It's a 3 hour version of 'strings for dummies'. I've seen torrents of it around. The website also includes some further material on discoveries since the book came out.
03-28-04, 01:13 AM
A good book that I bought a while back is "The Physics of Star Trek" by Lawrence M. Krauss.
It takes some of the theoretical stuff discussed or used in the Star Trek shows/movies and explains the why and how behind them. In theory of course. A good read if you are a physics fan, an even better read if you are also a star trek fan (even a casual one).
03-28-04, 09:30 AM
Allright, I'm actually into the meat of the paper, and now I can accurately describe what about the process of teleporting small matter I dont understand. If anyone has the answer to these, they get a cookie.
1. When we do the initial disruptive scan of the object, how do we go about this?
2. Are the EPR scans and the disruptive scans simultaneous or does the EPR scan happen first. It would stand to reason that EPR takes place first because if we disrupt more than we scan with the disruptive scan (lets say 61% gets disrupted for every 60% we scan), then we've disrupted information that cannot be retrieved by our EPR associations. I can reason which is done first, but I'm not willing to make that kind of logical leap.
3. I'm reading up on things that say EPR is actually a kind of light. (i.e. this and this) Any idea on how I can come to terms with this?
4. I'm still cloudy on how exactly the EPR connections retrieve their part of the information from the object being scanned. Do entangled particles X and Y get separated and then we entangle particle X with parts of the object we're scanning, which therefore makes particle Y immitate the object?
5. How do we reconstruct the object, both physical construction, and interperetation of scanned data. Because if we scan the data out of the EPR connection, doesnt that just disrupt it and make us run back into our good friend, Heisenberg?
You all have been a wonderful help so far, I know the policy of "don't take medical/academic/etc. advice from the safehouse" but most of what you all have been saying is backed up by a lot of the research I've found. The problem is before I see it in lay man's term's I can't understand what the hell my source is saying. Thanks a bunch for the help so far, and any you can provide on this next leg of the journey.