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axon
03-10-2004, 06:33 PM
interesting article for the physics lovers:

http://www.businessweek.com/magazine/content/04_11/b3874102.htm

your thoughts? I actualy read a similar article in this past Friday's Wall Street Journal...unfortunately I can't find it on their webpage.

your thoughts?

XSquared
03-10-2004, 09:13 PM
At my highschool, we had a researcher from the Perimeter Institute for Theoretical Physics (http://www.perimeterinstitute.com/) visit us and talk about the theory behind quantum teleportation, including entanglement, and the like. I personally found it quite interesting, although it went way over the heads of most of the other people in my class.

Clyde
03-11-2004, 09:47 AM
Quantum computation holds great potential, if it can be done and it is done i think the chemical revolution following it will be astounding.

Quantum mechanics itself is IMO a fascinating subject, its is probably the most powerfull theory of the twentieth century, and yet there is still debate surrounding the interpretation and how to resolve (and even i think if you need to resolve) some key issues like the measurement problem, and the EPR paradox.

caroundw5h
03-11-2004, 10:40 AM
Originally posted by axon
interesting article for the physics lovers:

http://www.businessweek.com/magazine/content/04_11/b3874102.htm

your thoughts? I actualy read a similar article in this past Friday's Wall Street Journal...unfortunately I can't find it on their webpage.

your thoughts? Damnit, i can't believe you beat me to it. I have no technical knowledge on this subject, but this seems to tell me - computer implications aside - time travel is possible, and parralell universes are real. there is a possibility for every possible choice one can make, which in my opinion is either a 1 or 0, yes or no.

if every one is a result of there yes or no choices -- never mind, this article is just exciting. I don't have enough knowledge to be babbling, but this article was wow!!!!

Dante Shamest
03-11-2004, 10:57 AM
in which each of many millions of atoms act identically and are everywhere in the sample at once

For real?

Is it saying all the atoms everywhere have the same properties....

or is it really saying that each atom is literally everywhere?

Ken Fitlike
03-11-2004, 11:22 AM
>>or is it really saying that each atom is literally everywhere?<<

Literally everywhere. They exist in a superposition of all possible states but some of these states are considerably more probable than others.

Clyde
03-11-2004, 11:33 AM
time travel is possible


The Bose-Einstein condensate does not indicate anything about time-travel.



parralell universes are real


There is an interpretation of quantum mechanics known as the "many worlds hypothesis" though as far as i'm aware its not a widely held view among scientists.



there is a possibility for every possible choice one can make


I'm not quite sure what you mean here.



or is it really saying that each atom is literally everywhere


It's trying to put quantum superposition into words, if you have a quantum system like say an electron in a small box prior to measurement the electron is not actually at one position with one momentum rather it is spread across multiple positions and multiple momenta. (edit: Ken beat me to it)

axon
03-11-2004, 10:04 PM
The wall street journal gives a very simple explanation and example to this rather hard to grasp subject, and I quote:


In a whimsical version of superposition, quantum pioneer Erwin Schrödinger once imagined a cat locked in a box with a radioactive atom. The atom has a 50-50 chance of decaying in one hour. If it decays, it emits a particle that hits a vial of cyanide and releases toxic gas, killing kitty. After an hour, is kitty alive or dead?
The standard answer is that the atom is on a superposition of intact and decayed, so kitty is in a superposition of alive or dead. Only when an observer peeks into the box does a single possibility - alive or dead - become an actuality.


I hope this clears up the whole subject a bit.

This leads to another topic that Heidegger wrote about many years ago, and that is that only philosophers and poets will understand the world and its nature. Scientists get the raw facts, but it is the philosophers that make heads or tails of it. This might seem ridiculous, but what about Einstein and his famous quote about the moon?

RoD
03-11-2004, 10:17 PM
>>although it went way over the heads of most of the other people in my class.

they done did what to the who now?

Clyde
03-12-2004, 05:57 AM
The standard answer is that the atom is on a superposition of intact and decayed, so kitty is in a superposition of alive or dead. Only when an observer peeks into the box does a single possibility - alive or dead - become an actuality.


Actually as far as i'm aware there is no standard answer to Schrodinger's cat. Schrodinger himself used this example to demonstrate an apparent absurdity of quantum mechanics. Schrodinger goes on to argue that the only way to resolve the paradox is to appeal to the limits of knowledge itself.

This is essentially the measurement problem:

You have a system like an atom in a superposition of states, when it get's measured it collapses down to a single state.... but if you put both the measuring device and the atom in another box, then they form a new system which is in superposition untill measured... etc. So when does this collapse occur? It looks like you would just end up with more and more superpositions, and yet we observe a definite world.

To clarify, imagine a person in a box, is the person really both alive and dead until measured by another person? and is then the person-person in a box system in all possible states untill measured by a third person... and on and on. This completely jars with our experience of the world around us.

Von Neuman (a mathematician who put quantum mechanics into a riigious mathematical framework) argued that the collapse occurs in the first conscious mind to observe the situation, so our cat is then not superpositioned after all and is really either dead or alive. But most people seem to reject this interpretation as it lacks any formal basis ie. why? how? does consciousness cause the wavefunction to collapse (interesting physicist Roger Penrose tries to answer these questions in his book "The Emperor's New Mind", i have yet to read it but again his arguments do not appeared to have swayed many physicists), and further given are knowledge of evolution is seems to throw into question how you could ever get the first conscious mind.

Most scientists who regularly use QM seem to go along with the view that when stuff gets big superposition collapses, some form of quantum decoherence goes on. Now as far as i know this also runs into problems because supposedly we have managed to place a cation into a superposition, a cation is a negatively charged atom and is small compared to a cat but as far as i know is large enough to mean problems for simple big = collapse views, which is why its sometimes jokingly refered to as Schrodinger's cation.

So that leaves us back at square one, where does the collapse occur? Some people do not even think there is a collapse at all, they think that QM is incomplete that a so called hidden variable model will reveal a hidden layer of determinism and solve all the quantum weirdness once and for all. This view is generally not accepted but I have come across some arguments convincing enough to make me want to read into it further.

The orthodox interpretation was developed by Heinsenberg, Bohr and Pauli but i still do not really know what it really says, i do know it is similar in some ways to the positivist philosophy adopted by people like Hawking that essentially claims talking about how reality "actually is" is meaningless, i think that ties in with what Heisenberg says about his cat paradox its beyond the limits of what is knowable but i'm not sure.

caroundw5h
03-12-2004, 03:56 PM
Originally posted by axon
The wall street journal gives a very simple explanation and example to this rather hard to grasp subject, and I quote:


I hope this clears up the whole subject a bit.

This leads to another topic that Heidegger wrote about many years ago, and that is that only philosophers and poets will understand the world and its nature. Scientists get the raw facts, but it is the philosophers that make heads or tails of it. This might seem ridiculous, but what about Einstein and his famous quote about the moon?

YOu mean like reality is only what we perceive it to be?

Dante Shamest
03-12-2004, 03:59 PM
Does this mean Elvis may still be alive?

axon
03-12-2004, 05:07 PM
>>Ou mean like reality is only what we perceive it to be?

more like only what we can see, as that example goes.

axon
03-12-2004, 05:07 PM
>>Does this mean Elvis may still be alive?

this means that you either have a brain or you don't.

JaWiB
03-13-2004, 09:08 PM
This whole subject is fascinating to me. I really should learn more about it rather than playing video games all the time ;)

Isn't this Bose-Einstein condensate the same one that light travels extremely slowly through?

caroundw5h
03-13-2004, 10:54 PM
by any chance have any of you ever heard of sitchin (http://www.dcsi.net/~bluesky/bs5.htm)

axon
03-13-2004, 11:53 PM
I've read something by him a long time ago...but what does he heave in common with our topic? :rolleyes:

caroundw5h
03-15-2004, 09:05 AM
Originally posted by axon
I've read something by him a long time ago...but what does he heave in common with our topic? :rolleyes: :o Just makes me wonder about exactly what we are discovering. whether if in the grand scheme of things this is only the tip of the iceberg. Just how much more farther do we have to go and has anyone discoered it all before. Sitchin believes that a group of individuals from another planet discovered much of what we are present day only now coming into awareness of. He believes we are only just now catching up to ancient technology. He believes we were gentically enginered for this planet by the Nefilim. He has very convincing arguments, using bilical facts, historical facts and even genetics to prove his point.
He discribed certain things the ancients already knew - like our solar system - with unbelievingly accuracy. Just makes me wonder how much are we being laughed at when we "discover" things like quntum physics. Plato was an intelligent man - ubelievingly intelligent. One who required facts to accept anything, and he swore that Atlantis existed. Just makes me wonder. thats all.
I chose my signature for a reason. If you get it, you get it. If you don't..can't help you.
Someone on this thread spoke about how this world is for the poets and philosphers - or its for us to understand. Either way i agree with them. I believe in each of us there is an innate ability to discern the secrets of the universe and our reason for existance - i also believe science is behind what many poets and philosophers already know about our abilities and universal possibilities. However being the nature that science is, it needs empirical evidence. Things it can put names to and manipulate. Poets just accept it and work with it.

Anyways. It just made me wonder thats all. It just made me wonder. Many years from now when our generation is just a memory faded to dust and scattered to the winds. Will our descendants laugh at our puny accomplishments? our ridiculous beliefs and customs? How much truth will they have discovered in comparison to us? Just makes me wonder that is all.
:o :confused:

Clyde
03-15-2004, 09:27 AM
Sitchin believes that a group of individuals from another planet discovered much of what we are present day only now coming into awareness of. He believes we are only just now catching up to ancient technology. He believes we were gentically enginered for this planet by the Nefilim. He has very convincing arguments, using bilical facts, historical facts and even genetics to prove his point


Sounds like high grade nonsense.



I believe in each of us there is an innate ability to discern the secrets of the universe and our reason for existance


The only innate ability is the faculty of reason and the only way to discover nature's secrets is to probe them with experiment.



Many years from now when our generation is just a memory faded to dust and scattered to the winds. Will our descendants laugh at our puny accomplishments? our ridiculous beliefs and customs?


We do not laugh at Newton we hold him up to be an example of a brilliant mind, customs and "beliefs" rarely age well but scientific advancement does, we do not look back at the accomplishments of Newton, Darwin or any of the legion of brilliant minds that have come and gone as "puny" nor indeed the artistic genius of Mozart or Shakespear, some feats do not lose their grandeur with age.



How much truth will they have discovered in comparison to us?


That is an interesting question, from our current point view it looks like we've got atleast part of reality fairly well sowed up, the accuracy of the standard model of particle physics is astoundingly good, but there remain major challenges that could herald revolutions in our understanding. Never the less i would be very suprised if the scientists of the future had done away with quantum mechanics.