Light waves

[steevey]

I've always been wondering why gamma rays always seem to act like particles, while radio waves which are also photons act more like waves than particles.

So I'm wondering now if the reason is because of the uncertainty principle:

The energy in a radio-wavelength photon is more precisely determined (or in general, just smaller) so its position is less determined, while in a gamma ray its energy is less precisely determined (or in general, larger) therefore its position is more precisely determined.

Edited February 18, 2011 by steevey

[lemur]

I sort of understand how you're applying the logic of the uncertainty principle here, but isn't the amount of energy in any photon precisely determined by the amount of energy that goes into generating it? And don't photons always get emitted in specific "quanta" according to wavelength? Why would one frequency's energy-quanta be more variable/fuzzy than another's? Are you saying there is more variability in emissions spectra at high frequencies than at lower frequencies? E.g. it would be harder to modulate a gamma wave like a radio wave for communications because the gamma wave would simply defy control more than the radio wave? Does the uncertainty principle even apply to photons or just electrons?

[steevey]

I sort of understand how you're applying the logic of the uncertainty principle here, but isn't the amount of energy in any photon precisely determined by the amount of energy that goes into generating it?

 

Well an electron has a specific mass, but that mass is a very precise small number. A proton has a very large mass compared to it, so its a more general number. Its sort of like accuracy in a sense. A smaller and smaller decimal of an irrational constant gives you a more accurate or more precise outcome when using it as a decimal, and a particle's wave function extends indefinitely through space, so in that analogy, a particle's existence like an irrational constant.

Edited February 18, 2011 by steevey

[lemur]

Well an electron has a specific mass, but that mass is a very precise small number. A proton has a very large mass compared to it, so its a more general number. Its sort of like accuracy in a sense. A smaller and smaller decimal of an irrational constant gives you a more accurate or more precise outcome when using it as a decimal, and a particle's wave function extends indefinitely through space, so in that analogy, a particle's existence like an irrational constant.

What you're describing sound like it is an equational artifact. When you're talking about an electron's mass, I think you should be focussed on whether you're referring to its momentum/force or its contribution to the mass of the atom. In relation to the nucleus, isn't the electrostatic force more significant than the mass? As for the wave-function extending indefinitely, isn't that just a mathematical probability? My sense is that the wave function is just an empirically-oriented approximation for the electrostatic force that governs how the electron will behave at various positions relative to the protons. The electrostatic field of the protons can also be described as extending infinitely away from the nucleus, I think, but you would probably focus on the part where the electrons most typically appear, right? Electrons "jump around," but the positive electrostatic fields of the protons they jump around in do not fluctuate, do they?

[steevey]

What you're describing sound like it is an equational artifact. When you're talking about an electron's mass, I think you should be focussed on whether you're referring to its momentum/force or its contribution to the mass of the atom. In relation to the nucleus, isn't the electrostatic force more significant than the mass? As for the wave-function extending indefinitely, isn't that just a mathematical probability? My sense is that the wave function is just an empirically-oriented approximation for the electrostatic force that governs how the electron will behave at various positions relative to the protons. The electrostatic field of the protons can also be described as extending infinitely away from the nucleus, I think, but you would probably focus on the part where the electrons most typically appear, right? Electrons "jump around," but the positive electrostatic fields of the protons they jump around in do not fluctuate, do they?

 

The thing is though, although a particle's wave function extends indefinitely through space, the probability of finding particles that far away become unimaginably small. It's like considering the gravity of Pluto here on Earth. Gravity goes on indefinitely, but it just gets really meaningless and close to nothing after a certain point.

But otherwise, a wave-function is mathematical, but its still derived from the observational fact that a particle can show up in places other than its most probable place, it's just unusual or less frequent, and the mathematical pattern that describes how it shows up in its most probable place also predicts it showing up in any place in the universe, but again, is very unlikely.

Edited February 18, 2011 by steevey

[swansont]

Compare the wavelength of a gamma vs a radio wave. Does that tell you anything?

[lemur]

The thing is though, although a particle's wave function extends indefinitely through space, the probability of finding particles that far away become unimaginably small. It's like considering the gravity of Pluto here on Earth. Gravity goes on indefinitely, but it just gets really meaningless and close to nothing after a certain point.

But otherwise, a wave-function is mathematical, but its still derived from the observational fact that a particle can show up in places other than its most probable place, it's just unusual or less frequent, and the mathematical pattern that describes how it shows up in its most probable place also predicts it showing up in any place in the universe, but again, is very unlikely.

So is there any difference between the concept of a wave-function as a description of the positive electrostatic field of the nuclear protons and using the same concept to describe the probability of a given particle showing up at a given position in a gravitational field at a given moment? E.g. could you say that any molecule that doesn't achieve escape velocity in a gravity field with no atmosphere (like the moon) would have wave function that predicts where that molecule could be at any given moment based on the amount of energy it receiving and expressing?

[steevey]

Compare the wavelength of a gamma vs a radio wave. Does that tell you anything?

 

That's what I was thinking, but I don't know for sure. In a gamma ray, the position and wavelength seems to be more determined but the energy is less determined, while in radio waves, the position or wavelength seems to be less determined while the energy seems to be more determined.

 

So is there any difference between the concept of a wave-function as a description of the positive electrostatic field of the nuclear protons and using the same concept to describe the probability of a given particle showing up at a given position in a gravitational field at a given moment? E.g. could you say that any molecule that doesn't achieve escape velocity in a gravity field with no atmosphere (like the moon) would have wave function that predicts where that molecule could be at any given moment based on the amount of energy it receiving and expressing?

 

Forces and effect where the most probable places are located, but a description of a particle's probable places is different than the forces acting on it. An atom could be by Earth, which has a smallish gravity, but an electron will continue to have a distinct area of probability around an atom even if it was by the sun which has a much higher gravity. The reason the area of probability would change for something other than its position is because of energy. If an electron gains enough energy to become unbound to any particular atom, it will exist as a wave bound to no particular region, although I think there is some sort of shape or concentration like a wave packet like this

 

or this

and I think the peak is the most probable place to exist, or the wave crest.

Edited February 18, 2011 by steevey

[swansont]

That's what I was thinking, but I don't know for sure. In a gamma ray, the position and wavelength seems to be more determined but the energy is less determined, while in radio waves, the position or wavelength seems to be less determined while the energy seems to be more determined.

 

 

The wavelength of a gamma is far smaller, making the interaction more localized.