# what is quantum mechanics?

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what is a simple difenition of quantum mechanics?

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Is this a trick question?

Some definitions:

http://en.wikipedia.org/wiki/Quantum_mechanics

I don't really know if it can get simpler than that. Some key concepts are quantization (discrete units), wavefunctions and uncertainty at sufficiently small scales. I suppose you could call it a branch of physics that describes the mechanics of microscopic systems that can't be accurately described with classical mechanics.

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I'd probably go with, it's mechanics on which scale the uncertainty principle is not negligable...

I suspect if you formulate it correctly from hamliton-jacobi mechanics you will get some nice equation which states the range over which it is applicable, which will have a h or maybe hbar in it.

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can i just say the interactions of all micro particles?

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can i just say the interactions of all micro particles?

No, antimatter is a special case where it can be considered to be matter going backwards in time. The maths is the same for both cases (antimatter and normal matter going backwards).

Normal matter does not have retrocausality.

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No, antimatter is a special case where it can be considered to be matter going backwards in time. The maths is the same for both cases (antimatter and normal matter going backwards).

Normal matter does not have retrocausality.

this is what really confuses me when im told anti matter is matter going back in time,then im told that they don't expierance retrocausality.what im asking is do anti particles or particles in reality travel back in time?

Edited by ps3
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Quantum mechanics is the study of mechanical systems whose dimensions are close to the atomic scale i think its a cool tech

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Quantum mechanics is the study of mechanical systems whose dimensions are close to the atomic scale i think its a cool tech

The shortcoming of this definition is that QM effects can creep up into macroscopic objects; the cutoff between QM and classical is not distinct.

QM is the treatment of the behavior entities as waves. I think Severian once pointed out that "wave mechanics" would be a more apt description.

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What does that mean?

I got that def from wikipedia.

Wave mechanics is alien to me:confused:

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Probably best for you to avoid commenting in a fashion that seems like you're answering a question, and spend more time asking them then, eh?

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i remeber someone telling that a particle is an anti particle moving backwards in time and time travel to the past was all mixed in with feynman's diagram and t-symmetry.

Edited by ps3
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I'd probably go with, it's mechanics on which scale the uncertainty principle is not negligable...

How would you employ this definition to the photo electric effect and the quantinization of radiation?

Pete

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How would you employ this definition to the photo electric effect and the quantinization of radiation?

Pete

An interesting question. One that can apply equally to:

Quantum mechanics is the study of mechanical systems whose dimensions are close to the atomic scale i think its a cool tech

In a lab at my uni we deal with microwaves that are a few cm in wavelength, clearly not atomic scale and yet you've got to use QM to analyse them....

I think to apply either of them you have to look at the interactions, so the photons are interacting on a scale where both statements are true.

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i remeber someone telling that a particle is an anti particle moving backwards in time and time travel to the past was all mixed in with feynman's diagram and t-symmetry.

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I got that def from wikipedia.
Thanks for letting us know, but next time you cut and paste, reference the source in the same post, OK? Otherwise it's plagiarism.
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what confussed me is if there is any time travel going on in reality?

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We move forward in time at a rate of one second per second.

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Probably best for you to avoid commenting in a fashion that seems like you're answering a question, and spend more time asking them then, eh?

Shut up u dont know everything.

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Shut up u dont know everything.

I agree that I don't know everything, but that's no reason to be so rude in response to a comment that is correct.

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What does that mean?
swansont said:

QM is the treatment of the behavior entities as waves. I think Severian once pointed out that "wave mechanics" would be a more apt description.
He's pointing out that QM really should be known as WM.

Wave mechanics is alien to me:confused:
WM = QM, at least according to Severian (he's one of our physicist members).

Shut up u dont know everything.
Hey! Knock it off! If you want to be understood, don't use textspeak.

And if you want iNow to be civil, don't tell him to "shut up". Ask him if his choice of words was deliberately condescending or if he was dropped hard as a baby. There's probably evidence linking the two and I know he'll appreciate the perspicacity.

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swansont said:

He's pointing out that QM really should be known as WM.

WM = QM, at least according to Severian (he's one of our physicist members).

Yes indeed.

In quantum mechanics nearly everything you do is an application of the mathematics of waves to mechanics problems, so wave mechanics

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or if he was dropped hard as a baby.

I assume that you're joking? Is there a forum policy/rule about not using ad hominem attacks? If not then, IMHO, there should be.

QM is the treatment of the behavior entities as waves. I think Severian once pointed out that "wave mechanics" would be a more apt description.

I disagree. There is more to quantum mechanics than a solely wave description can handle. For example; the state ket

$|\psi> = a|+> + b|->$

represents the super position of a particle which in a superposition of the spin up state and the spin down state. There is no wave function associated with this ket.

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I assume that you're joking? Is there a forum policy/rule about not using ad hominem attacks? If not then, IMHO, there should be.

Would you please give it a rest?

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I disagree. There is more to quantum mechanics than a solely wave description can handle. For example; the state ket

$|\psi> = a|+> + b|->$

represents the super position of a particle which in a superposition of the spin up state and the spin down state. There is no wave function associated with this ket.

And there are quantities on the atomic scale that are not quantized.

The post I responded to stated that QM applied at the atomic scale and below, and that's not really accurate. IMO it's more accurate to say it's the scale when you may have to start treating things as waves rather than as classical particles.

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I assume that you're joking? Is there a forum policy/rule about not using ad hominem attacks? If not then, IMHO, there should be.
No assumption necessary when you use the big green smile.

I know that iNow responds better to an exaggerated and obvious jest than to offended superiority, and I hoped to pass that gem on to Physiman. Smile and wave, that's my motto.

Hey, wave! We're back on topic!

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