Thread: People who know about Quantum Mechanics/Physics/Thoery Please come here

Just to warn you, there are going to be a lot of people posting here who claim to know about quantum mechanics but don't actually understand it very well. Really, no one on this site is going to understand it well, since it is a very technical field of physics that requires some very serious study.

The best way to get a good introduction to quantum mechanics is to read a book called "The Elegant Universe" by Brian Greene. The book is actually about string theory, but a large portion of the book is dedicated to first introducing the reader to both general relativity and quantum mechanics in easy to understand terms.

As for your question about the double slit experiment; without knowing specifically what video you were talking about, its hard to tell if it was wrong or not. It has been shown that attempting to observe which slit the electron actually passes through does effect the outcome, but scientists do not claim that this means that the electron "knows" it is being watched. As of now, the way in which the observation affects the outcome isn't really known.

I highly recommend the Elegant Universe as well. It's such a great read, really flows along, unlike most scientific texts.

I don't think an electron's path has to do with being observed. I think the electrons take every possible path, and their end result is derived from the sum total of possible paths available to it. Can't remember where I read that though...

The double slit experiment is when a stream of particles, be they photons, electrons, or even recently, C-60 molecules, is shot at two slits whose separation is comparable to the deBroglie wavelength of the particle in question. When this happens, a rather unintuitive thing happens. First of all, each particle goes through one of the slits (we don't know each one, and in fact, the experiment will only work if it can't be determined which one) and ends up as a seemingly randomly distributed point on the screen. However, if you shoot many particles, even one at a time so they never touch each other, the points on the screen will form a distinct diffraction pattern of bright lines and dark lines. Thus, it appears as though the particles somehow self-interfered going through the slit, and then decohered to single particle after they left. Or in other words, they went from particle to wave to particle again.

We actually did a cheaper variation of that experiment in college. It's really freaky when you prove it with your own eyes. Beware, however of success guru's (such as the creators of the "Secret") who attempt to convince you that you can shape reality via your thoughts. That hit "Secret" movie even references the double slit experiment as "proof" that observation can control reality. Sure it happens at the tiny quantum level but the marketers make an invalid leap into the macroscopic world where, according to them, reality is being shaped by our observations.

I think that Secret video is what you might have seen. If so, Google "The Secret" and you'll find out more information. In the past, many followers of metaphysics claimed to be able to get rich and succeed by simply altering their thought patterns. "The Secret" is simply a variation of that idea packaged with a fancy bow and sold to the world as a scientific breakthrough backed by "proof", that of course being quantum mechanics. Some people do refer to this "Think and Grow Rich" philosophy as cultish. I saw portions of the Secret movie.
In it a boy, using his mind and quantum mechanics alone is able to control a basketball precisely enough to hit the basket without fail.
Millions of folks have fallen for it and bought the book/dvd/movie/course. Larry King even had the creators on one night.

Remember, however, the quantum phenomenon is indeed real AT the quantum level. That's why quantum computer development is so challenging. And, yes it is kind of scary knowing that a simple particle KNOWS if you're watching it.
It's not a theory, it's a verifiable fact. Once you get into quantum entanglement and "teleportation" it really gets strange.

Originally Posted by Lucid Lobster

We actually did a cheaper variation of that experiment in college. It's really freaky when you prove it with your own eyes. Beware, however of success guru's (such as the creators of the "Secret") who attempt to convince you that you can shape reality via your thoughts. That hit "Secret" movie even references the double slit experiment as "proof" that observation can control reality. Sure it happens at the tiny quantum level but the marketers make an invalid leap into the macroscopic world where, according to them, reality is being shaped by our observations.

I think that Secret video is what you might have seen. If so, Google "The Secret" and you'll find out more information. In the past, many followers of metaphysics claimed to be able to get rich and succeed by simply altering their thought patterns. "The Secret" is simply a variation of that idea packaged with a fancy bow and sold to the world as a scientific breakthrough backed by "proof", that of course being quantum mechanics. Some people do refer to this "Think and Grow Rich" philosophy as cultish. I saw portions of the Secret movie.
In it a boy, using his mind and quantum mechanics alone is able to control a basketball precisely enough to hit the basket without fail.
Millions of folks have fallen for it and bought the book/dvd/movie/course. Larry King even had the creators on one night.

Remember, however, the quantum phenomenon is indeed real AT the quantum level. That's why quantum computer development is so challenging. And, yes it is kind of scary knowing that a simple particle KNOWS if you're watching it.
It's not a theory, it's a verifiable fact. Once you get into quantum entanglement and "teleportation" it really gets strange.

I don't think the OP would like this to turn into a debate on the power of positive thinking. You should keep your comments to the discussion of quantum mechanics and physics.

Originally Posted by Xaqaria

I don't think the OP would like this to turn into a debate on the power of positive thinking. You should keep your comments to the discussion of quantum mechanics and physics.

Good point. But actually, I may have answered his question if the video that he was viewing was the Secret. The Secret is based almost entirely on quantum mechanics. It even shows the double slit experiment. The Secret is the only logical possible connection that I can make based on White Wolf's original question,

"I saw a quantum mechanics video and some are saying it's a cult".

If his question had instead been, "Is there truth to the quantum slit experiment that I saw?" the answer would have been a simple "yes".

I guess the debate about the Secret stems from their claim that the mind can control particles at the detailed quantum level as opposed to the power of positive thinking philosophies which are entirely different. Because there are not many scientifically based quantum slit experiments on YouTube while there are tons of "the Secret" quantum slit experiment videos, I'd wager that that the Secret is the one that White Wolf saw. I believe it's called "Down the Rabbit Hole" - a clever reference to the Alice and Wonderland type magical world of Quantum Mechanics.

"What the Bleep do We Know" is another cult-ish New-Agey pseudoscience video based on QM.

Originally Posted by esfx

"What the Bleep do We Know" is another cult-ish New-Agey pseudoscience video based on QM.

That one sucked, in my opinion.

This was a post I made a little while ago, maybe it helps?


part 2
part 3


part 2
part 3


part 2
part 3

that the group that made the video are cult trying to bring people in the cult and also the book I'am reading now does explain the experiment and from what I got from the book I think the video is wrong totally

There are tons of garbage out there. Not all of it, though.
Might want to keep that in mind. If someone tells you what
you 'should' believe, then chances are, the're off. :-)

Thanks everybody who replied. I'am positive that esfx knows what video I'am talking about. It was something like "what the bleep do we know?", Also The title in Youtube had someting like Dr. Quantum or Mr.Quantum it's a cartoon film/video... Oh yea I'am sure I will go and read the book that you guys suggested really interested now. I've also wanted to read books on general relativity and quantum and String theory I guess the book that you guys suggested is an all in one package yahoooo !!!!
K anyways back to Quantum stuff the place I'am in the book is talking about the double slit experiment but a different take on it. It is talking something about delayed choice or something like that. The book is quite confusing when it tries to explain the experiments. But any how thanks a lot guys.

P.S. Gotta check my school library for that book if the don't have that book then I guess I gotta go buy it from Amazon.

Originally Posted by WhiteWolf

Thanks everybody who replied. I'am positive that esfx knows what video I'am talking about. It was something like "what the bleep do we know?", Also The title in Youtube had someting like Dr. Quantum or Mr.Quantum it's a cartoon film/video... Oh yea I'am sure I will go and read the book that you guys suggested really interested now. I've also wanted to read books on general relativity and quantum and String theory I guess the book that you guys suggested is an all in one package yahoooo !!!!
K anyways back to Quantum stuff the place I'am in the book is talking about the double slit experiment but a different take on it. It is talking something about delayed choice or something like that. The book is quite confusing when it tries to explain the experiments. But any how thanks a lot guys.

Delayed choice is a concept in which the decision to 'see' which slit the particle went through is made after it has already gone through. Wheeler's delayed choice experiment showed that even when one chooses to look at what slit the particle went through after it has gone through,, the choice to look still has an effect on what the particle did. Wheeler suggested that the choice could be dragged out indefinitely and this would still be true with the example of a photon going around a star. You may know that sufficiently massive bodies in space, like large stars, bend light with their gravitational field. This picture is of two stars, one in the foreground and one in the distant background. The four points of light around the center one are actually all coming from the same star, the light has just been bent around the massive star in the foreground. If you read down on that first link I posted, you'll see that the experiment suggests that even though the photons have passed the star billions of years ago, we can still effect which side of the star the photons appear to pass based on our decision to detect it or not.

Wow thanks a lot Xaqaria for that website really informational. The book "The Elegant Universe| was taken out damn!!! I have another question what is like the genral Idea of Quantum. For instance the thing about the uncertainty thing, or the copenhengan (notsure if I spelled that right or not) iidea.
Thanks anyway

Originally Posted by WhiteWolf

I have another question what is like the genral Idea of Quantum.

Just watch some Dr Quantum videos.
http://www.youtube.com/results?searc...q=0&oq=dr+quan

I am not a physicist, but I am pretty certain that some of the major principles of quantum physics, such as the Uncertainty Principle and non-determinism, are illogical notions. It appears that quantum physics is to science what left wing ideology is to politics. It is a mass of rationalizations away from reality that allow certain people to pretend that they are extra-intellectual when really they are just extra-dishonest. Watch what happens to the field of physics over the next few decades. I predict that bullshit will be called and proven in our lifetimes.

Originally Posted by Universal Mind

I am not a physicist, but I am pretty certain that some of the major principles of quantum physics, such as the Uncertainty Principle and non-determinism, are illogical notions. It appears that quantum physics is to science what left wing ideology is to politics. It is a mass of rationalizations away from reality that allow certain people to pretend that they are extra-intellectual when really they are just extra-dishonest. Watch what happens to the field of physics over the next few decades. I predict that bullshit will be called and proven in our lifetimes.

Most of the people that really understand quantum mechanics would agree with you that it is/seems illogical. The famous Niels Bohr quote, “If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet” exemplifies that. I'd also like to point out (as I believe I have before) that few or no scientists who study quantum mechanics make the claim that reality is fundamentally uncertain, but only that the way in which we are capable of interacting with reality on the quantum level is fundamentally uncertain. Does it not make sense to you that in order to observe something, one must interact with it, and to interact with something changes it?

I'm also not exactly saying that reality itself necessarily isn't uncertain, only that no one really makes any claims about it one way or the other because it is impossible to know.

I'd like to ask you though, why is it that you seem to accept the evidence for things like evolution, and really all other aspects of science, but disregard the evidence behind quantum mechanics? Do you agree with general relativity, which also seems illogical to the casual observer?

Originally Posted by Xaqaria

Most of the people that really understand quantum mechanics would agree with you that it is/seems illogical. The famous Niels Bohr quote, “If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet” exemplifies that. I'd also like to point out (as I believe I have before) that few or no scientists who study quantum mechanics make the claim that reality is fundamentally uncertain, but only that the way in which we are capable of interacting with reality on the quantum level is fundamentally uncertain. Does it not make sense to you that in order to observe something, one must interact with it, and to interact with something changes it?

I agree with that much of it, but Heisenberg went further than that, or at least his analysis was taken further than that by interpreters of it. It is a common belief among quantum physicists that reality itself is uncertain, not just humans trying to analyze and predict it.

Also, Hawking said, "God does play dice," to contradict Einstein's claim, "God does not play dice." He was arguing against determinism.

Originally Posted by Universal Mind

I agree with that much of it, but Heisenberg went further than that, or at least his analysis was taken further than that by interpreters of it. It is a common belief among quantum physicists that reality itself is uncertain, not just humans trying to analyze and predict it.

Also, Hawking said, "God does play dice," to contradict Einstein's claim, "God does not play dice." He was arguing against determinism.

I won't speak for hawking or any other particular person, but I think the difference is that it is easy to talk about our perception of reality as being "Reality" since its the only version of it that we are capable of being aware of. Our perception of reality is fundamentally uncertain, as far as we currently know. I know it is a very fine line, but its one that I personally choose not to cross because it would be presumptuous to believe that we can make statements about some theoretical objective reality that we have absolutely no evidence for, nor will really ever be capable of finding such evidence.

Originally Posted by Universal Mind

I agree with that much of it, but Heisenberg went further than that, or at least his analysis was taken further than that by interpreters of it. It is a common belief among quantum physicists that reality itself is uncertain, not just humans trying to analyze and predict it.

QM has many different interpretations but Heisenberg is not responsible for one.

Science is based on evidence, QM has made some impressive predictions like anti particles and without it stuff like ultraviolet catastrophe would happen. You can't just dismiss something because it seems strange too you.

On another point QM has been Mathematically formalised. Look up matrix mechanics.

Originally Posted by Universal Mind

Also, Hawking said, "God does play dice," to contradict Einstein's claim, "God does not play dice." He was arguing against determinism.

I'm pretty sure Hawking has a better understanding of the universe then you. On another thing, here http://en.wikipedia.org/wiki/Bohr-Einstein_debates

Einstein lost the debate. Ironically, his great critism became the famous EPR experiment. You should look up EPR.

Originally Posted by wendylove

QM has many different interpretations but Heisenberg is not responsible for one.

He is responsible for the Heisenberg Principle, also known as the Uncertainty Principle. It is not meant to explain all of quantum physics, but it is one of the principles of it.

Originally Posted by wendylove

Science is based on evidence, QM has made some impressive predictions like anti particles and without it stuff like ultraviolet catastrophe would happen. You can't just dismiss something because it seems strange too you.

I don't dismiss the whole thing. I dismiss some of the principles of it.

Originally Posted by wendylove

I'm pretty sure Hawking has a better understanding of the universe then you.

That does not mean I can't see poor logic in one of his points. I'm pretty sure George W. Bush has a better understanding of how the world works than you. Does that mean you can never see poor logic in something he says about it?

Originally Posted by wendylove

Einstein lost the debate. Ironically, his great critism became the famous EPR experiment. You should look up EPR.

Read the very end of the article you posted.

http://www.ipod.org.uk/reality/reali...ntum_intro.asp

Originally Posted by Dog Biscuits

http://www.ipod.org.uk/reality/reali...ntum_intro.asp

wow, just read the first four chapters, very interesting!
I have read and heard some things but it's really great
to read that in a "from start to finish" timeline-way. thanks!

Also it seems to give a pretty good picture.
But I will continue reading that tomorrow, since
it's really not easy stuff and especially since
I don't natively speak english,.. I had to reread
some of the paragraphs over and over.

But I guess since it's quantum physics it might be understandable

Particles behave like waves because particles are bunched up waves.

If mass is energy and energy is waves, then mass is waves, bundled up

here you can take an entire stanford course on quantum physics.

http://www.youtube.com/view_play_lis...7CEA1B8B27EB67

Originally Posted by Dog Biscuits

Particles behave like waves because particles are bunched up waves.

If mass is energy and energy is waves, then mass is waves, bundled up

It sounds nice that way, but it isn't exactly true. Energy is not waves, it is the ability to do work. Potential energy is a static form of energy. Most forms of energy that people think of (like electromagnetic) are actually particles just like matter.

Also, you interpretation doesn't really leave room for situations in which particles don't behave like waves, which is most of the time.

The problem facing modern physics is that we have two sets of rules to describe the universe. We have relativity for the very large and very fast, and quantum mechanics for the very minute.

Since we know the atomic make up and behavior of stars and such, we should be able to predict their behavior at a macroscopic level using quantum mechanics. Likewise we should be able to deduce the quantum specifics of large scale objects from our knowledge of the behavior on the macroscopic level. But in either case, it just doesn't work.

Really, we should only have one set of rules to describe the universe, and the inability of the two theories to mesh really screws things up. That's why String or M-Theory is considered a "unified theory", and a working unified theory is the holy grail of modern physics.