If a Tree Falls in a Forest...

Lisandro

...and no one is around to observe it, does that tree make a sound?
























No, it's a quantum tree.

IRWolfie-

It is in a superposition of the making a sound state and not making a sound state.

Anonymo

This is an old one. This being a physics forum the answer is unequivocally yes. The tree when it falls will create a pressure/sound wave due to its impact on the ground. The sound wave is what physics defines as sound. In other domains, sound is defined more as the sensory reaction to the sound wave. In that case, if there is nobody around then the answer would be no. Essentially the answer to this question is an exercise in semantics!

krd

Anonymo wrote: »

This is an old one. This being a physics forum the answer is unequivocally yes.

No. The tree is actually in a superposition of not only having fallen or not, but an infinite number of other possible states.

You have to integrate all the possible paths the tree may have taken to the ground, then realise the figures look ridiculous - so then you re-normalise them. Then the tree has fallen, but in another universe it hasn't - so it depends on what you universe you're in. But in one of the universes you will be there to hear the tree fall, and in another you won't.

So, does the tree falling make a sound or not?......The answer is unequivocally both.

Anonymo

krd wrote: »

No. The tree is actually in a superposition of not only having fallen or not, but an infinite number of other possible states.

You have to integrate all the possible paths the tree may have taken to the ground, then realise the figures look ridiculous - so then you re-normalise them. Then the tree has fallen, but in another universe it hasn't - so it depends on what you universe you're in. But in one of the universes you will be there to hear the tree fall, and in another you won't.

So, does the tree falling make a sound or not?......The answer is unequivocally both.

Incorrect. We are told that the tree fell. You are trying to make this into a Schrodingers cat type of argument which it isn't (as it's phrased in any case).

Anonymo

Anonymo wrote: »

Incorrect. We are told that the tree fell. You are trying to make this into a Schrodingers cat type of argument which it isn't (as it's phrased in any case).

In fact if you want to make a quantum argument about this, you could make one about the coherency of the wave function itself. The usual properties of the wave that we would perceive, i.e. the localisation of the pressure wave, is only true in a quantum sense when we observe the wave. Thus it is the sound wave itself that you can invoke the quantum criterion to. In this sense there may indeed be a superposition of sound and no sound, unless we are there to observe it. So your answer, krd, is correct but for the wrong reason!

IRWolfie-

Anonymo wrote: »

Incorrect. We are told that the tree fell. You are trying to make this into a Schrodingers cat type of argument which it isn't (as it's phrased in any case).

I suppose the correct answer then is: it didn't fall if noone observed it. The question is flawed.

krd

Anonymo, I liked the way you were able to pass your opinion through two comments and create an opinion interference pattern.

twistyj

If a tree falls and no one is around, does the hipster still buy the soundtrack?

doctoremma

Anonymo wrote: »

This being a physics forum the answer is unequivocally yes. The tree when it falls will create a pressure/sound wave due to its impact on the ground. The sound wave is what physics defines as sound.

Interesting. My answer to this question is always "no", as, with the lack of a detector, the pressure waves are not converted into a sound.

Are you saying that a physicist would (and legitimately) describe the pressure waves as a "sound" wave, even with the recognition that nothing is there to convert the pressure into a sensory experience? Or is the use of "sound" wave a bit of a shorthand?

And the same applies to "light"? In that even with the lack of a detector (or one able to detect the appropriate wavelength), you still use the word "light" in a formal sense?

Morbert

The question is actually regarding an entirely different philosophical issue. It is about solipsism, and mind vs reality, not about how "sound" should be defined.

locum-motion

Will you all stop trying to answer the original question: it was evidently posted just to set up the punch line of a joke, not looking for an answer!

The original question itself is a nonsensical one.

Lisandro

Anonymo wrote: »

Incorrect. We are told that the tree fell. You are trying to make this into a Schrodingers cat type of argument which it isn't (as it's phrased in any case).

Actually, no, it is a Schroedinger's cat situation. It's a classical scenario hijacked by quantum mechanics.

Anonymo

No it isn't. Like I said we are told the tree fell. There is no ambiguity. We're told the tree fell. If we were told that Schrodingers cat had died there would be no problem with the Schrodingers cat (aside from its mortality)!
The second argument I gave about the collapse of the wave function itself to form a coherent sound is also just a stretch to make this debate into a quantum argument. But the scales that such an argument are valid on are microscopic compared to the expected amplitude of a sound wave created by a falling tree so I don't actually think that it's relevant in this case.

Lisandro

Anonymo wrote: »

No it isn't. Like I said we are told the tree fell. There is no ambiguity. We're told the tree fell. If we were told that Schrodingers cat had died there would be no problem with the Schrodingers cat (aside from its mortality)!
The second argument I gave about the collapse of the wave function itself to form a coherent sound is also just a stretch to make this debate into a quantum argument. But the scales that such an argument are valid on are microscopic compared to the expected amplitude of a sound wave created by a falling tree so I don't actually think that it's relevant in this case.

We're not debating whether or not the tree fell, we're debating whether or not it made a sound. I would suggest that the Schroedinger's cat equivalent would be, "If we know for certain that a cat and a cyanide capsule are stuck in a box, does the cat die?" rather than the one you provided. In other words, we have an a priori established fact from which we want to infer if a certain event follows or not.

The point is, however, we only know that a tree generates pressure waves (from empirical evidence) if it is a classical tree. Because it is actually a quantum tree, there is a non-zero probability amplitude corresponding with the scenario in which the tree falls, but does not cause the molecules of its surroundings to vibrate and generate sound. Making an observation of the tree falling collapses this wavefunction, which yields the joke's punchline.

I can't believe I'm making a serious argument about a joke, because this all presupposes the existence of such a quantum tree, which we have never observed in reality!

Anonymo

Lisandro wrote: »

We're not debating whether or not the tree fell, we're debating whether or not it made a sound. I would suggest that the Schroedinger's cat equivalent would be, "If we know for certain that a cat and a cyanide capsule are stuck in a box, does the cat die?" rather than the one you provided. In other words, we have an a priori established fact from which we want to infer if a certain event follows or not.

The point is, however, we only know that a tree generates pressure waves (from empirical evidence) if it is a classical tree. Because it is actually a quantum tree, there is a non-zero probability amplitude corresponding with the scenario in which the tree falls, but does not cause the molecules of its surroundings to vibrate and generate sound. Making an observation of the tree falling collapses this wavefunction, which yields the joke's punchline.

I can't believe I'm making a serious argument about a joke, because this all presupposes the existence of such a quantum tree, which we have never observed in reality!

grand but the 'point' you make is a rehashing of an earlier comment I made.

Lisandro

Anonymo wrote: »

grand but the 'point' you make is a rehashing of an earlier comment I made.

That point was the reasoning behind the punchline, I didn't just come up with it after you started posting. As well as that, when I read your comment, I thought you meant localisation of the sound wave as opposed to the sound wave's wavefunction, but if its wavefunction is what you meant, I don't know why you said it wasn't a Schroedinger's cat situation.

Edit: I just reread the post that was in response to, where the poster talked about amplitudes of the tree falling and not falling. Different Schroedinger's cat criterion then.