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Old Sep 2nd 2014, 04:45 PM   #1
MBW
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Is the Universe Random?

Does Physics describe a fixed deterministic universe?

At the quantum level there only seems to be a probabilistic description of behaviours,
and this appears to be the actual basic essence of existence at this level.

At the macroscopic level things seem to average out to give a completely predictable outcome, but is the universe fundamentally random?
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Old Sep 2nd 2014, 11:17 PM   #2
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Originally Posted by MBW View Post
Does Physics describe a fixed deterministic universe?

At the quantum level there only seems to be a probabilistic description of behaviours,
and this appears to be the actual basic essence of existence at this level.

At the macroscopic level things seem to average out to give a completely predictable outcome, but is the universe fundamentally random?
It would appear to be somewhat random. There are some restrictions on how many random variables you actually have, so chaos doesn't reign supreme. But almost.

-Dan
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Old Sep 4th 2014, 04:01 AM   #3
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Originally Posted by MBW View Post
...but is the universe fundamentally random?
I don't think so. IMHO things happen for a reason.

Originally Posted by MBW View Post
At the quantum level there only seems to be a probabilistic description of behaviours
It isn't a true. That's just the Copenhagen interpretation. It's adherents will tell you that's how it is, they won't tell you it's just one idea about how things are. If you look around you can find articles on "weak measurement" like In praise of weakness. You can also find Jeff Lundeen's web site where you can read his semi-technical explanation:

"So what does this mean? We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory."
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Old Sep 4th 2014, 11:34 AM   #4
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Originally Posted by Farsight View Post
"So what does this mean? We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory."
There is also one other major contender besides the Copenhagen Interpretation...it's called "Many Worlds." This is essentially the idea that new Universes are created by every quantum "decision" made. It sounds kind of ridiculous but it makes exactly the same predictions that the Copenhagen Interpretation does. You have a choice about which uncomfortable interpretation you want to work with.

I'll admit that I haven't followed the links you provided but I must ask...How do you think you can redefine the wavefunction as something else more "measurable?" The wavefunction is what it is. If you want to talk about something else then fine. But there is no way to redefine it.

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Old Sep 4th 2014, 12:02 PM   #5
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Originally Posted by topsquark View Post
There is also one other major contender besides the Copenhagen Interpretation...it's called "Many Worlds." This is essentially the idea that new Universes are created by every quantum "decision" made. It sounds kind of ridiculous...
I'm not a fan of the MWI. To be perfectly blunt I think it's pseudoscience woo. I really don't know how it was ever taken seriously.

Originally Posted by topsquark View Post
I'll admit that I haven't followed the links you provided but I must ask...How do you think you can redefine the wavefunction as something else more "measurable?" The wavefunction is what it is. If you want to talk about something else then fine. But there is no way to redefine it.
That's what Jeff Lundeen said. He's basically saying it's something real right there in the lab. And that it's not just some probability thing.

See Aephraim Steinberg's website http://www.physics.utoronto.ca/~aephraim/ and Jeff Lundeen's website: http://www.photonicquantum.info/ . These guys and their et als were first and second place in the Physicsworld breakthroughs of 2011, see http://physicsworld.com/cws/article/...oughs-for-2011

"Second place goes to another group that has asked a "forbidden question". Led by Jeff Lundeen at the National Research Council of Canada in Ottawa a former colleague of Steinberg a team has used weak measurement to map out the wavefunction of an ensemble of identical photons without actually destroying any of them. Quantum tomography, in contrast, maps out the wavefunction at the expense of destroying the state. As well as boosting our understanding of the fundamentals of quantum mechanics, the technique could prove useful in cases where tomography cannot be used."
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Old Nov 2nd 2014, 06:32 AM   #6
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Sketchy Analogy

These weak measurement techniques seem to be a way of gaining a statistical analysis of the wavefunctions of a large number of "identical" particles (photons in the case of experiment described in the website link).

Is there a sense in which the wavefunction is an emergent property of many particles, perhaps a bit like pressure in a gas.
It is difficult to talk about the "pressure" of a single atom/molecule, but put a lot together and take the average, and the concept becomes much more meaningful.
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Old Nov 3rd 2014, 02:32 PM   #7
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If the universe is infinite then all possibilities are... and each occurs infinitely through space and time, this creates a fractal through space and time... would that be random or predetermined? Mute point me thinks!
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Old Nov 3rd 2014, 06:31 PM   #8
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Originally Posted by Troll View Post
If the universe is infinite then all possibilities are... and each occurs infinitely through space and time, this creates a fractal through space and time... would that be random or predetermined? Mute point me thinks!
(sighs) Will you please stop talking about the *&^** fractals until you can present a consistent theory with them. You have not supplied one in the past and I doubt you will now.

Knock it off.

-Dan
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Old Nov 5th 2014, 03:51 PM   #9
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Originally Posted by topsquark View Post
(sighs) Will you please stop talking about the *&^** fractals until you can present a consistent theory with them. You have not supplied one in the past and I doubt you will now.

Knock it off.

-Dan
The idea of an infinite universe is not new! How could it not produce fractals?
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Old Nov 5th 2014, 05:07 PM   #10
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Originally Posted by Troll View Post
The idea of an infinite universe is not new! How could it not produce fractals?
For the same reason I keep telling you about.

Look, let's try this. An infinite Universe does not imply that anything can happen. In fact such a state could be disastrous. All of the "spacey" sciences all have one core assumption: The entire Universe (whatever that may be) runs under the same physical laws that can be measured here and around Earth. So, for example, General Relativity has been measured to be a reasonably decent theory of gravity in the Solar System. Since we can't directly measure anything in the Large Magellanic Cloud we have to assume that GR works well there too until given evidence to the contrary.

Back to the infinite Universe: Not everything is possible...The only things possible are those that can happen according to any reasonable theory; It is stuff that is governed by the same laws as are in our own backyard.

You aren't going to find fractals out there because you don't get them here, either.

-Dan
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