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Author Topic: where does the direction of gravity come from?  (Read 5251 times)

Offline thebrain13

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where does the direction of gravity come from?
« on: 27/10/2010 19:32:23 »
If particles have no "true" location before they are measured. In what direction does gravity come from when an object is still in transit?


 

Offline Bill S

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where does the direction of gravity come from?
« Reply #1 on: 27/10/2010 19:46:46 »
thebrain13, are you talking about individual particles (quons, sensu Nick Herbert)? if so, without a theory of quantum gravity, it may be difficult to answer this question.
 

Offline thebrain13

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where does the direction of gravity come from?
« Reply #2 on: 27/10/2010 20:25:46 »
ya, if one electron travels through a twin slits apparatus. Where is the gravity coming from between the times the electron is emitted and received?
 

Offline Soul Surfer

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where does the direction of gravity come from?
« Reply #3 on: 27/10/2010 23:22:11 »
The answer to the question is perfectly obvious it is  whatever direction the apparatus and direction of particle/wave travel was set with respect to any local gravitational field while the experiment was being performed.  In general this has no effect on the results unless the gravitational field is extremely strong.
 

Offline Bill S

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where does the direction of gravity come from?
« Reply #4 on: 28/10/2010 00:40:07 »
Quote
without a theory of quantum gravity, it may be difficult to answer this question.

I was thinking more of particles in a "zero gravity" situation when I made that comment.
 

Offline thebrain13

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where does the direction of gravity come from?
« Reply #5 on: 29/10/2010 22:00:18 »
soul surfer, I didn't mean what direction is gravity going to pull obviously it is "down", I meant is the gravity going to be viewed as coming from a point, or a spread out smudge of the electrons probability wave? remember quantum mechanics says the location of a particle is not determined until it is "viewed". So where is the gravity coming from when an electron is still in transit? Is it one place or many?
« Last Edit: 29/10/2010 22:14:18 by thebrain13 »
 

Offline Bill S

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where does the direction of gravity come from?
« Reply #6 on: 30/10/2010 17:13:42 »
Quote from: thebrain13
So where is the gravity coming from when an electron is still in transit? Is it one place or many?

Is it in any way meaningful to ask where the gravity is coming from when the electron is in transit?  When superposition is involved; is there a real distinction between one place or many?  In fact, when the electron is in transit, can we be sure that the electron even exists, as such?

Then again; if the electron does not become "real" until it is observed, perhaps there is no gravity involved until it is observed. 

Makes yer 'ead spin, dunnit?
 

Offline NotSoGrim

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where does the direction of gravity come from?
« Reply #7 on: 31/10/2010 01:19:59 »
remember quantum mechanics says the location of a particle is not determined until it is "viewed". So where is the gravity coming from when an electron is still in transit? Is it one place or many?

OMG, I love the thought of gravity not having a direction without a 'view'.  Stop looking and you never know where you will end up :o ;D
 

Offline Soul Surfer

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where does the direction of gravity come from?
« Reply #8 on: 31/10/2010 11:10:33 »
In general, gravity plays absolutely no significant part of particle interactions until it is extremely strong and outside the observable limit.   it is just about possible to detect gravitational deflection of particle beams in the lab under extremely cold conditions  as far as the way the particles behave it is just as if the particle was any projectile falling under the influence of gravity.  Quantum effects do not cause deviations from classical behaviour under these conditions.
 

Offline yor_on

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where does the direction of gravity come from?
« Reply #9 on: 31/03/2011 23:31:44 »
:)

Sweet thinking Brain.
If the moon isn't there when I'm not looking, shouldn't gravity scream :)
 

Offline thebrain13

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where does the direction of gravity come from?
« Reply #10 on: 01/04/2011 00:58:04 »
I'm glad you brought this topic back up. As soul surfer says, gravity is too small and insignificant to measure. And Its a pretty reasonable bet that we will never find out for sure where gravity comes from in context of an individual particle. However, that does not diminish the fact that this question WITHOUT A DOUBT has an answer. Gravity is coming from somewhere, it has to come from either one spot or many, there are no other options.

In my opinion, if they actually did create an experiment sensitive enough to measure if the gravity from one particle comes from one spot or many while "not being viewed" it would be a big hit to the idea that objects only exist when we look at them.
 

Offline imatfaal

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where does the direction of gravity come from?
« Reply #11 on: 01/04/2011 14:21:12 »
I'm glad you brought this topic back up. As soul surfer says, gravity is too small and insignificant to measure. And Its a pretty reasonable bet that we will never find out for sure where gravity comes from in context of an individual particle. However, that does not diminish the fact that this question WITHOUT A DOUBT has an answer. Gravity is coming from somewhere, it has to come from either one spot or many, there are no other options.

In my opinion, if they actually did create an experiment sensitive enough to measure if the gravity from one particle comes from one spot or many while "not being viewed" it would be a big hit to the idea that objects only exist when we look at them.

Nope - this is the desire to impress a classical view onto a non-classical situation.  It is this human necessity to reduce all ideas to classical simplicity that bell's theorem shakes - simple either/or questions can become unanswerable.
 

Offline yor_on

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where does the direction of gravity come from?
« Reply #12 on: 01/04/2011 22:05:17 »
In a way that is true Imatfaal. but QM still have a way to go if they want to reduce everything to 'quanta/particles'. Einsteins SR and GR seems to work any which way as far as I know. But I agree, QM have shown us some remarkable properties as HUP (Heisenberg's Uncertainty Principle) for example. The problem isn't to prove them wrong, rather to find a way of describing it that rhymes with the theory of relativity. And that you can do differently, defining it all as motion, energy and particles/quanta, or start to try to reduce the parameters expected first, and then look at what that reduction might bring you.

Is there one thing both relativity and QM tells you, then it is that we're prejudiced, just by being born where we are.

« Last Edit: 01/04/2011 22:06:48 by yor_on »
 

Offline JMLCarter

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where does the direction of gravity come from?
« Reply #13 on: 01/04/2011 22:21:09 »
Before we move on to gravity I would like to know where does a photon come from when it is emitted by an electron wave function constrained to an atom.

Is the answer not that the photon is a wave function too, so on that scale its origin is undetermined (until measured).

The same would be true of virtual force carriers, photons and presumably of gravitons if they ever get discovered some day in the distant future.
« Last Edit: 01/04/2011 22:27:34 by JMLCarter »
 

Offline JP

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where does the direction of gravity come from?
« Reply #14 on: 01/04/2011 22:51:07 »
Before we move on to gravity I would like to know where does a photon come from when it is emitted by an electron wave function constrained to an atom.

Is the answer not that the photon is a wave function too, so on that scale its origin is undetermined (until measured).

The same would be true of virtual force carriers, photons and presumably of gravitons if they ever get discovered some day in the distant future.

I'm not sure I understand your question fully, but in general if you have to write the electron as a wave function, you're describing it as a bunch of possible electrons in different positions.  You can write an emitted photon as a bunch of different photons emitted from those different electrons, rather than a single photon emitted by one electron transition.  In a sense, they're entangled, such that if you measure the photon and it "chooses" one state to be in, then your electron must have been in the same state, but until you measure it your photon and your electron can be in many states.

It might be easier to think of the analogy of the two slit experiment.  The number of slits is analogous to the number of states an electron could be in.  In the simple case that you have one slit, which is analogous to knowing your electron's state, the photon you measure is just given by a contribution from that one slit.  If you have two slits, then the photon suddenly becomes a combination of a photon coming from slit 1 and a photon coming from slit 2 (the electron analogy would be that your photon is a combination of a photon from electron state A and one from electron state B). 
 

Offline yor_on

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where does the direction of gravity come from?
« Reply #15 on: 02/04/2011 03:28:17 »
It's such a nice view of reality :) All paths taken, or none, just letting probability create it. I think Feynman is/was right in that he's suggesting that there should be something more than just uncertainty ruling, although I think it all lies in the interactions myself. Well, I do :) I don't like propagation :) Too lazy?
 

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where does the direction of gravity come from?
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