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Old Apr 22nd 2008, 09:01 AM   #1
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New take on an Old question

If a particle whizzes through the universe,but doesn't interact with any other particles,does it exist?
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Old Apr 22nd 2008, 10:08 AM   #2
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Originally Posted by MBW View Post
If a particle whizzes through the universe,but doesn't interact with any other particles,does it exist?
I see someone has been taking walks in the forest and looking at the trees.

Well, the particle can't be seen, heard, felt, or more importantly measured.

According to Classical Physics, the answer is "Why not?"

According to Quantum Theory I would say that the existence of such a particle can only be postulated if the particle is self-aware, so it can be its own observer. The rest of the Universe cannot observe the particle and the particle cannot observe the rest of the Universe. Which, then, has the more "real" existence? The particle or the Universe?

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Old Apr 22nd 2008, 10:31 AM   #3
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Originally Posted by MBW View Post
If a particle whizzes through the universe,but doesn't interact with any other particles,does it exist?
If the particle has mass then it has to interact with ALL other particles in the universe.
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Old Apr 22nd 2008, 10:49 AM   #4
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I guess it could be argued that a particle is defined by its iteractions (eg mass).

Even a neutrino has to interact, at least at one end of its existance.

I suggest that existance is imposible without interaction.

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Old Apr 23rd 2008, 10:46 AM   #5
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Well as far as the possible existence of such a particle in current theory I would agree that this situation is impossible. Even a massless particle has energy (as it has to travel at speed c its frequency would have to be 0 Hz in order to have no energy, and such a "particle" has no meaningful existence), and so must still move under the influence of gravity, and hence will cause all other particles in the Universe to be influenced by it, according to Newton's 3rd law.

However it is fun to speculate on what would happen...

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Old May 1st 2008, 10:24 AM   #6
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Just playing with ideas...

OK, we seem to have concluded that interaction is a necessary prerequisite for existance.

If so what is the simplest possible universe that could be postulated?
2 particles interacting via a third intermediary?

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Old May 1st 2008, 10:55 AM   #7
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Originally Posted by MBW View Post
OK, we seem to have concluded that interaction is a necessary prerequisite for existance.

If so what is the simplest possible universe that could be postulated?
2 particles interacting via a third intermediary?

Mark.
Probably. Of course, then we have the question, "Interacting in what kind of space?"

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Old May 2nd 2008, 07:34 AM   #8
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What is space?

Are particles and their interactions kinks in the fabric of spacetime,
or is spacetime a product of the interaction of particles.

Or are they both a product of our imperfect human interpretation of reality.
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Old May 3rd 2008, 07:13 AM   #9
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Originally Posted by MBW View Post
What is space?

Are particles and their interactions kinks in the fabric of spacetime,
or is spacetime a product of the interaction of particles.

Or are they both a product of our imperfect human interpretation of reality.
Good question. I think that the current wisdom attributed to the Quantum Field Theory versions of General Relativity have space-time as a kind of fluid that reacts to the presence of mass and energy. More on this I am not able to say with any certainty.

The issue is not really that a particle can exist that is non-detectable, the issue is whether such a particle has any relevence to our Universe. By definition such a particle cannot. What this means is that could be any number of undetectable "layers" to our own Universe: sets of particles (and perhaps even people?) that we cannot see. However Occam's razor cuts this argument to shreds: If we can't detected it supposing an existance for it is meaningless.

So as far as "human reality" goes, space-time is what we view it, and the Mathematical models are going to dominate. One possible viewpoint that would take space-time to be a constructed hallucination takes the form that perceived distance is merely the result of a quantum operation measuring a property which we call displacement. So the "space" of space-time is merely a Mathematical construction that our eyes give us because they can perceive (or use) that quantum operation. This is not such a silly notion: Most field theories assume the existance of such Mathematical, but not physical, dimensions. So why should space itself be any different?

-Dan
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Old Nov 27th 2013, 07:24 AM   #10
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Hmm... Well I think you are familiar with my toroidal fields. If they do exist and are the primary constituents of the universe, then the existence of a particle is an interaction. The particles existence would affect everything in the universe. We may not be able to measure it, but esoterically it does exist because it may have interaction that we can measure in the future.

Does the universe exist outside of what we can observe?
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