Really good presentation of HUP and the Casimir effect by 60 Symbols:



Can't get youtube tags to work, sorry.

Edit: Fixeded. Weird, it didn't work like that on the old server.

Love that channel.

hackenslash wrote:Really good presentation of HUP and the Casimir effect by 60 Symbols:

https://youtube.com/watch?v=IRcmqZkGOK4

Can't get youtube tags to work, sorry.

You have to change the "https" to "http" i.e. drop the s....

Thanks for the link!

Very weird effect....not sure I understand why putting plates in place PREVENT long-wavelength particles from being created...guess the difference between 'space' and 'matter' Hmmm.....

kennyc wrote:Very weird effect....not sure I understand why putting plates in place PREVENT long-wavelength particles from being created...guess the difference between 'space' and 'matter' Hmmm.....

What causes the reaction is, in essence, duality. It is known that all particles are observational manifestations of the excitations of fields, but they have another aspect, namely the wave-like manifestation. In short, each particle comes with an associated wave. That's not entirely accurate, in fact, but it's close enough for our purpose here. As with all waves, these waves come in varying lengths.

Now we have to go back to the birth of QM, and some work done by Max Planck. He was thinking about the energy inside an oven. When he added up all the frequencies, he realised that the resultant energy should be infinite, which is clearly nonsense, because if the energy were infinite it would be hotter than the sun. So he thought about how some of the frequencies could be excluded and thus not contribute to the energy. He realised that, if he excluded all the frequencies whose wavelength was such that it couldn't reach the 'zero crossing' (an audio term for a similar phenomenon) within the walls of the oven, it couldn't contribute. Here's an image of a sine wave to demonstrate:



As you can see, the wave starts at the zero line, goes up, comes back down and through the zero line, then down and back up. This is a complete cycle (1 cycle per second equals 1 Hertz = 1Hz). For the sake of simplicity, let's assume an oven whose walls are 20 units apart. This wave would be allowed, because one cycle completes in 20 units. If the wavelength were twice that, it would also be allowed, because 1/2 cycle could complete in 20 units. If the wavelength were half that, it would also be allowed, because it completes two cycles in 20 units. Only frequencies whose waves reach the zero crossing exactly, whether by half or a full Hz, is allowed to contribute. This is quantisation, and it is the reason why it's called Quantum Mechanics.

Now, coming back to the Casimir force, again, only frequencies that can complete a half or full cycle exactly and reach the zero crossing precisely at the plate can exist between the plates, while outside, all frequencies are allowed. This means that there is more energy outside the plates than inside, which creates a pressure differential, drawing the plates together.

TMI, but yeah, I get it...

What I find interesting is the synchronicity of your having posted this as I have been mulling over the concept of virtual particles and Hawking radiation the last couple of days.....have to have something to keep me occupied eh? I think there is a poem forming in the black hole of my muse's subconscious consciousness.....

hackenslash wrote:

kennyc wrote:Very weird effect....not sure I understand why putting plates in place PREVENT long-wavelength particles from being created...guess the difference between 'space' and 'matter' Hmmm.....

....

Now, coming back to the Casimir force, again, only frequencies that can complete a half or full cycle exactly and reach the zero crossing precisely at the plate can exist between the plates, while outside, all frequencies are allowed. This means that there is more energy outside the plates than inside, which creates a pressure differential, drawing the plates together.

Which means (as I said above in minimalistic terms) the presence of matter prevents the 'creation' of the virtual particles....which is a bit weird in itself whether the can be measured/detected/ or not, but that appears to be what is happening if in fact we can measure the 'pressure' pushing the plates together.....but again totally weird.....

Here's a crazy thought, perhaps this pressure could be somehow used (like the Bernoulli principle) to cruse interstellar space!

There seems to be one little issue with his explanation, and that is that photons, as chargeless bosons, are their own anti-particle, so cannot annihilate with each other in the manner of, say, electrons and positrons (and when electrons and positrons do annihilate, the result is two photons, not nothing). I guess this has to do with annihilation of virtual particle pairs being somehow diffferent from annihilation of real particle pairs, but this aspect seems to have been glossed over.