/sci/ - Science & Math

>>5492740
If you mean the "Dr. Quantum" video that makes the mistake explained in the picture, then yes, that video is inaccurate. Quantum mechanics is not bullshit, but I think you knew that.

>>5492740
but you do get #2 for a single slit

>>5492740
no you still get a diffraction pattern

Sure, everything you don't understand is bullshit.

http://en.wikipedia.org/wiki/Single_slit_diffraction#Single-slit_diffraction

gtfo Hs fags

>>5492752
So what does that imply ? Can we all agree that this is bullshit ?

Fixed the image to deal with the concerns of
>>5492746
>>5492752

If the slits were as wide in comparison to the spacing between them as the original image showed, you would indeed expect to see the single-slit diffraction bands on a diagram that shows the double-slit bands.

>>5492777

>>5492784
Yeah, that's better. Missed that.

>>5492765
Yep

Trolling isn't a function of effort. It's about simplicity and subtlety. You need people to believe you are serious. Your post has all the subtlety of a freight train. That's why you have so few replies. Look at the "Portal A or B" post for an example of an effective troll.

>>5492765
The double slit experiment is not bullshit. You can trivially perform the basic version of the experiment yourself by making a pair of slits and shining a laser pointer through them toward a distant wall in a dark room. If you don't screw something up, you will see an interference pattern.

If you are asking whether there are experiments where the presence of a conscious observer changes the interference pattern created, then no, there are not.

>>5492852
> actual chart that makes a point
> calls troll because he cant comprehend what it says
this is sad...

>>5492927
Dude, you can't bring this thread back, it's too obvious. Go back to the drawing board. The hint you should get from the "Portal A B" troll is that you need something to argue about that doesn't have an objective resolution.

>>5492959
Since you've gone full defensive mode, I assume you seriously didn't get anything or you're trolling yourself. I bet on the second option. Anyway, rest of the people in this thread understood what it says except for you, so thanks for the bump but I got the answer, so you can leave now.

The double slit experiment is definitely not bullshit.

The belief that it means that our looking at an electron collapses it's wave-function as if it has anything to do with being conscious is definitely bullshit.

The belief that it means that our looking at an electron collapses it's wave-function in a physical way as a result of photons is probably an incorrect quirk of what the math seems to be telling us, but it might actually be like that.

Double-slit experiment sounds like the name of a really bad physics-related lesbian porno.

>>5492982
> The belief that it means that our looking at an electron collapses it's wave-function as if it has anything to do with being conscious is definitely bullshit.
It's the fault of the lack of explanation really. When it says observer, people automatically assume it must be a human or a conscious being. And they automatically conclude that photons have to do something with consciousness.

>>5492980
Are you getting mad?

Does a p-doped semiconductor have a conduction band?

>>5493010
Yes, it just has more holes in the valence band than electrons in the conduction band.

Any means of measuring the position of the particle as it passes through the slits necessarily transfers momentum from the measuring device to the particle. Changing the particle's momentum changes the position of the fringes. And the momentum transfer is random and different for each particle, so it has the effect of blurring the pattern, taking you from (1) to (2). If (3) were what happened, that would be very weird, but it isn't.

It's possible to measure the momentum of your measuring device and correct for it to reconstruct the interference pattern you see in (1), but doing so necessarily destroys the information about which slit the particle went through. You can even set it up so that the choice to measure position or momentum takes place after the particle has hit the screen. They've actually tried this IRL, except in the real experiment, they didn't use momentum to reconstruct the (1) pattern but a different variable.
http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

There's no experiment where having a conscious observer makes any difference. If you measure which slit the particle went though and don't look at it, you still get pattern (2).

>>5493015
Why do n-doped semiconductors have three times the conductivity as p-doped?

>>5493041
Surely this figure of three depends on what material you're using and how strongly you dope the stuff? But it shouldn't be surprising for holes and electrons to contribute differently to the conductivity. You would expect the effective mass of electrons and holes to be different at the very least.

>>5493078
I was taught that the same amount of doping leads to three times more conductivity for n-doped versus p-doped. Allegedly it has something to do with the states or the the number of states that "holes" must tunnel to compared to that of electrons.

>>5493073
IIRC the n doping pushes the Fermi level/energy just above the band gap letting a lot of electron to be mobile in the near empty conducting band

>>5493084
Well, the effective mass is definitely one factor, but I don't know enough about this to say if there are any others.

>>5493090
How?

That isn't a sufficient explanation. :\

>>5493104
Effective mass? What do you mean? The "hole" is the same mass as an electron because it is actually electrons moving.

>>5493109
A few(lot) free levels for electrons(virtual positrons) to move around in p type compare to a ton(few) of level the same amount of electrons(virtual positrons) can move in n type. In Si electrons move 3.11111111 times faster than virtual positrons so 3 time the conductivity.


http://en.wikipedia.org/wiki/Electron_mobility#Relation_to_conductivity

>>5493118
You're not really dealing with free electrons, just electrons that behave sort of like free electrons. I don't know how familiar you are with quantum mechanics, but when you work out the dynamics of the particles, they move as if they had a different mass than they really do.
http://en.wikipedia.org/wiki/Effective_mass_%28solid-state_physics%29

>>5492859
>>5492982
>>5493002
>>5493064
Thank you all very much. I have been misled by TV.

>>5493134
The math doesn't come out of a magic hat. There is an explanation. I'm wondering what it is.