Wave particle duality? Magic?

[Jazzz]

ZWord, I was pretty freaked by the double slit experiment when our physics teacher went over it.

"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe, is as good as dead: his eyes are closed."

 

[angry bob]

Well Feynman reckons it does, at least it shows the duality within light.

No he doesn't and no it doesn't.

The double slit experiment demonstrates the wave-nature of light.

(as all of your original links make clear).





(or else I'm completely missing something)

 

[888]

no, it demonstrates the wave-particle duality, because you fire a single electron (particle) at a time, but it still makes an interference pattern.

http://physicsweb.org/articles/world/15/9/1

(we're not talking about the old double-slit experiment performed with trillions of photons at once)

 

[gurrier]

no, it demonstrates the wave-particle duality, because you fire a single electron (particle), but it still makes an interference pattern.

http://physicsweb.org/articles/world/15/9/1

(we're not talking about the old double-slit experiment performed with trillions of photons at once)

Yep, but one should bear it in mind that it just shows that photons are funny things that are neither classical particles, nor classical waves. They are released in discrete packets and they interfere with each other as if they were waves with a particular frequency. In reality, both of these effects and all the quantum funniness are probably just manifestations of whatever is going on at the levels that are too small for us to look at (eg strings).

 

[laptop]

Donald M. Eigler was involved in imaging the "electron corral" at IBM's Thomas J Watson research centre:

He gives a nice quote in an (Open University?) program on quantum mechanics:

"If you treat it as a wave, you get the right answer every time".

I take him to be suggesting that the "particle nature" of an electron is merely a result of thinking the wrong way about what the equations are saying.

 

[888]

In reality, both of these effects and all the quantum funniness are probably just manifestations of whatever is going on at the levels that are too small for us to look at (eg strings).

That's just what you'd like to believe. There's no evidence at all for that. There's probably no reassuring ultimate cause.

 

[gurrier]

That's just what you'd like to believe. There's no evidence at all for that. There's probably no reassuring ultimate cause.

Not at all. I'm not at all attached to string theory and don't want to believe anything in particular about wave-particle funniness, just the idea that when things behave in ways that seem paradoxical to us, it's normally because we are ignorant about what is going on at levels that are not visible to us.

I really hope there isn't an ultimate cause. It would be pretty shit if we were able to express everything in terms of an equation. I optimistically assume that every fresh level of understanding that we arrive at will open the door to ever more layers of seriously weird shit.

 

[ZWord]

Yeah, but no matter how weird it gets, you'll neer believe it's intelligent or that the intelligence that it is, is.

The paradox of Schrodinger's cat has a very simple resolution,

The cat knows whether it's alive or dead, obviously.

How come no physicist has pointed this out?

 

[laptop]

Zword - look up Wigner's Friend. Far more interesting than Schroedinger's cat.

And if you think about it clearly you'll see why the cat's awareness or otherwise is not relevant.

 

[angry bob]

no, it demonstrates the wave-particle duality, because you fire a single electron (particle) at a time, but it still makes an interference pattern.

http://physicsweb.org/articles/world/15/9/1

(we're not talking about the old double-slit experiment performed with trillions of photons at once)

It demonstrates the wave-particle duality of electrons, not light.

All this talk about doing the experiment at home is nonsense (unless you have your own electron gun).

 

[angry bob]

Yep, but one should bear it in mind that it just shows that photons are funny things that are neither classical particles, nor classical waves. They are released in discrete packets and they interfere with each other as if they were waves with a particular frequency. In reality, both of these effects and all the quantum funniness are probably just manifestations of whatever is going on at the levels that are too small for us to look at (eg strings).

OK someone really had better point me to a link to back this up.

Otherwise I'm gonna continue to say that:

the double slit experiment does not demonstrate the wave-particle duality of light

and it does not tell us anything about photons ... it points to the wave-nature of light and thus implies the non-existence of photons.

It was used by Young to effectivly disprove Newton's idea that light was particles.

 

[FridgeMagnet]

I optimistically assume that every fresh level of understanding that we arrive at will open the door to ever more layers of seriously weird shit.

It's elephants all the way down, you know.

 

[angry bob]

Yeah, but no matter how weird it gets, you'll neer believe it's intelligent or that the intelligence that it is, is.

The paradox of Schrodinger's cat has a very simple resolution,

The cat knows whether it's alive or dead, obviously.

How come no physicist has pointed this out?

That's beside the point.

The most widely accepted resolution is that the triggering of the geiger counter constitutes the measurement.

It is hardly satisfactory though ... but does at least avoid alll the bullshit about human consciousness.

The point of Schrodingers cat was to show how absurd QM is on a macroscopic scale.

 

[gurrier]

OK someone really had better point me to a link to back this up.

Otherwise I'm gonna continue to say that:

the double slit experiment does not demonstrate the wave-particle duality of light

and it does not tell us anything about photons ... it points to the wave-nature of light and thus implies the non-existence of photons.

It was used by Young to effectivly disprove Newton's idea that light was particles.

The single photon version of the experiment can hardly prove the non-existence of photons!

I think that the 'particle' part of the experiment springs from the discrete nature of the light emitted - ie the 'wave' is emitted in a discrete packet corresponding to a precise amount of energy in an all or nothing way - if you add 99% of the energy required nothing comes out, if you add 100% of the required energy a photon comes out. If you add 199% a single photon still comes out - which is, as I understand it, where the 'particle' nature of light comes into it (and as I noted above, it doesn't mean that light is a particle, just that it behaves as if it were one in being composed of discrete and integral packets).

 

[angry bob]

The single photon version of the experiment can hardly prove the non-existence of photons!

I think that the 'particle' part of the experiment springs from the discrete nature of the light emitted - ie the 'wave' is emitted in a discrete packet corresponding to a precise amount of energy in an all or nothing way - if you add 99% of the energy required nothing comes out, if you add 100% of the required energy a photon comes out. If you add 199% a single photon still comes out - which is, as I understand it, where the 'particle' nature of light comes into it (and as I noted above, it doesn't mean that light is a particle, just that it behaves as if it were one in being composed of discrete and integral packets).

I had never heard of the 'single-photon' version, until now. Hardly something you could do at home though!

Your energy argument is the basis of the photoelectric effect and does indeed demonstrate the particle nature of light.

 

[MysteryGuest]

I had never heard of the 'single-photon' version, until now.

They showed it on telly as part of those christmas science lectures, a couple of years ago, with a ?laser turned right the way down so that photons came out one at a time, and a detection screen hooked up to a camera. It was absolutely amazing to watch single photons gradually build up a wave-like interference pattern.

 

[ZWord]

It's elephants all the way down, you know.

No, turtles..

And according to this guy I heard, the one at the bottom has got something to say.