Friday, November 23, 2007

Honey, I doomed the universe!

Those of you familiar with the famous Schrodinger's Cat thought-experiment -- in which a cat's very survival is dependent upon the effect our observations may or may not have upon the quantum system in which it's said to be entangled -- will be interested to hear that according to two "controversial" physicists, the entire universe is in the same position as that cat.

One false observation, they claim, and apparently our universe gets it! Story here from 'New Scientist' magazine: Have we sealed the universe's fate by looking at it?

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9 Comments:

Anonymous Anonymous said...

I never fully understood that cat thing.

11/23/2007 03:30:00 pm  
Anonymous Falafulu Fisi said...

Here is how the Schrodinger's Cat's (SC) is interpreted in a real world experiment. The SC interpretation says, that the cat is neither alive nor dead in a sealed box. While the box is closed (unobserved), the cat is both alive & dead simultaneously. If an observer is to opened the sealed box and peek in to see what state the cat is at, then the cat only (collapses) materializes into one of the two states (ie, alive or dead) but not both, as it is interpreted when the box is unobserved (still sealed).

To summarize:

#1) When the cat is not being observed (ie, the observer can't see anything since the box is still sealed) ---> The interpretation is that the cat is both alive and dead simultaneously.

#2) When the cat is being observed (ie, when the observer opens the lid of the sealed box and tries to peek in to see what state either alive or dead state - that the cat is in) ---> What is being observed in real experiment (using sub-atomic particles) is that the cat only materializes into either one of the 2 states, depending on what the observer way of looking at it (or how he chooses to measure the state of the cat).

You can watch an animation of Schrodinger's Cat (SC) here at YouTube. Here is how the experiment is interpreted, and remember that this is real, you could see this at a University Physics lab near you about the double slit experiment using single photon (or electron) source. The relation of this real experiment to SC is something like this. The source in the YouTube animation is an electron gun. The gun fires a stream of electrons (particles) towards the double slit and then observes the distribution of how the particles are being detected at a screen behind the slits. In Copenhagen Interpretation, an electron is like a cat, ie, it is neither a real particle nor a real wave (as in ocean wave concept, etc), but it is both. It exists as a particle and a wave simultaneously, until an observer (the experimenter) decides to peek in and find out what state (particle or wave) that the electron is in. In the process of peeking in to see what state the electron is in, the electron (collapses) materializes into one of the 2 states (particle or wave) depending on the methods the observer chooses to adopt to peek in.

Dr Quantum - Double Slit Experiment

PS: The experiment had been replicated with molecules and the same thing is being observed as the double slit animation shown above. So, do we think that molecules are waves or particles? If you don't look (observe or measure), then it is both, but once you measures (peek in) , it only reveal itself as one of the 2 (a particle or a wave). It is inferred , that the universe obeys this interpretation.

11/23/2007 06:40:00 pm  
Blogger KG said...

A neat explanation, FF.
Something else which I find fascinating in particle physics is the apparent "communication" between particle pairs.
(ie particles separated in an accelerator, a force is applied to deflect the course of one particle and the other particle alters course by exactly the same amount)
Very strange indeed....

11/23/2007 10:34:00 pm  
Anonymous Falafulu Fisi said...

Yes KG, that is the instantaneous communication between a correlated particles. It is called quantum entanglement. This was first observed at Insbruck University about 10 years ago, and many others have replicated the experiments since then .Physicists have now keep pushing the the distance even further and into kilometers of fibre-optics apart. They send 2 (correlated) particles in opposite directions via fibre-optics from a laser source in the middle. One photon say, travels thru arm A fibre-optic cable, and the second one travels in say arm B. No matter how far apart these particles have traveled away from the source (in the middle) respectively, if one (an observer) perturbs (ie, does experiment) with one particle (say the one at arm A), he would immediately know the outcome at arm B without observing it. It seems somehow that these 2 correlated particles do communicate with each other at a speed faster than light, which is a contradictory according to relativity. Here is another animation by Dr. Quantum again at YouTube, but this video clip is not that good as his other video clip for the double-slit I have posted in my last message.

What is Quantum entanglement

11/24/2007 12:05:00 am  
Anonymous lgm said...

Taking the Copenhagen Interpretation further, one soon sees that what is in the box has many simultansous states which collapse into one state on opening the box to peek. Yes, the creature in the box is also a dog, a horse, Paris Hilton (with no clothes on- surprise, surprise) and a P-lab (the preferred state of the consensus of scientists) simultaneously. It is only once the observer peeks in that it collapses into one state or another. Hopefully it will be the naked, living and writhing Paris Hilton (complete with bottle of baby oil), otherwise the oberver will have to close the box and try again.

Interestingly, Schrodinger did not believe the Copenhagen Interpretation of his thought experiment. Obvioulsy he was not a fan of Paris Hilton.

Oh well.

LGM

11/24/2007 07:41:00 am  
Blogger KG said...

Wow! Thanks Falafulu--I had no idea this stuff was available on YouTube.
Maybe this way more people will become interested.
There are more than enough mysteries in the universe to keep us occupied, without having to invent spooks, eh?

11/24/2007 08:38:00 am  
Blogger Brian S said...

This comment has been removed by the author.

11/24/2007 10:35:00 am  
Blogger Brian S said...

Guys,

I think the point of PC's post was to pooh-pooh the Copenhagen Interpretation, which, basically, is an attempt to evade explanation.

11/24/2007 10:39:00 am  
Anonymous Falafulu Fisi said...

Yeah Brian, I am now not in favor of the Copenhagen Interpretation on the basis that it is subjective and not objective.

I had a recent debate over the blogospheres with some proponents of paranormal (psychic believers), and they quoted that paranormal capability is the result of Quantum Mechanics (entanglement), because we're all interconnected with everything else in the Universe (ie, the Copenhagen Interpretation - CI). This claim by psychics is all being dreamt up to retrofit their present mentality that these phenomena does actually exit physically. We all know that that paranormal phenomena is bollocks, because it has been demonstrated time and time again in controlled experiment that they don't exist. They only exist in the minds of the deluded.

I realized that I can't win in debating with psychic believers, if I cling to the unintuitive principles of CI, because I am dismissing their claims that paranormal exists on one hand but at the same time, I can't reject their claims that psychic phenomena is explained by quantum mechanics, since that can never be verified. This is exactly the same as the cat lives and dies simultaneously, ie, it can never be physically verified.

I frequently quoted the following article to psychic proponents to read, since the article clears some of the misconceptions. It also debunked the claims by psychic proponents that quantum mechanics explains paranormals.

Quantum Quackery

11/24/2007 09:13:00 pm  

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