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Originally Posted by Eratosthenes
sjastro,
the quantum fluctuations and perturbations were "blown out" during the inflation and expansion period. The variation in density, both with respect to baryonic matter and energy, we observe today are a reflection of the initial fluctuations. In fact it is argued that the trigger for the Big bang is a consequence of quantum instability or fluctuations. What was the nature of the initial singularity that the Big Bang sprouted from? Was is "ideally" perfect? In that case why would it become unstable and trigger a big bang?
Although the Big bang theory isnt settled yet with various cosmological models operating in the Physics market place, the fluctuations in the initial conditions seem to be providing remnants/artifacts on a large scale for Astronomers to observe today. Of course they could be just that - artifacts of our lack of understanding or equipment limitations etc. Who knows.
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Peter,
We seem to be discussing two separate issues here.
I'm referring to the variations in the structure of the CMB not the Universe itself.
The only mechanism that may relate to quantum fluctuations affecting the CMB is B mode polarization of photons due to inflation. This effect however is very subtle compared to the other mechanisms I have mentioned.
In fact the investigation of B-mode polarization in the CMB due to inflation is one of the more embarrassing cases for mainstream science.
It's "discovery" was announced by the BICEP2 team last year and was hailed as one of the greatest recent scientific discoveries rivalling the Higgs boson.
Unfortunately the researchers underestimated the amount of magnetized dust in our own galaxy that produces a similar photon polarization.
The mistake was realised after the Planck probe revealed its data.
So at this stage we have no direct evidence of the CMB being affected by quantum fluctuations.
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Some argue (like Einstein throughout his life) that quantum mechanics, although very accurate and validated by experimentation and measurement, is a Stochastic model of the atomic (and cosmic) world, and a deterministic model may yet be discovered by science. On the other hand, it may prove to be impossible to describe the atomic world with a deterministic model. Who knows?
My gut feeling is that every "scale" science has delineated for convenience or necessity is intimately linked and intertwined in some fundamental way. Finding the linkages or a global model of some kind may well be beyond human endeavors (or just around the corner)
Who knows?
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There are "Theories of Everything" ranging from String theory to Loop and Quantum gravity theories that incorporate GR into Quantum mechanics in "various degrees". Then there are more direct applications of GR into Quantum mechanics pioneered by Stephen Hawking and are generally referred to as Quantum Field Theory in curved space time.
Some aspects of String Theory do not appear to be falsifiable, other such as Quantum gravity are mathematical nightmares that are overwhelmed by infinities when one attempts to calculate the quantum state changes.
The theories are a starting point in a unified field theory.
These theories do make predictions which can either support or sink the theory. For example Hawking's theory predicts that Black Holes can evaporate.
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(and yes, the imaginary number system is very useful in many fields of science and engineering, including electrical engineering as you state. But the square root of negative 1 is undefined by definition, it "exists" (not exists) on an "imaginary" (real) number line as do i^3, i^5, i^7....i^odd integer. But i^2, i^4, i^6....i^even is fine by me)
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Since simple complex numbers can be represented as a coordinate on an X-Y graph there is nothing terribly unreal about imaginary part of the number when they are interpreted geometrically.
They can be used in vector analysis.
A simple example is a target shooter. On a windless day the shooter aims directly at the target and shoots with a muzzle velocity which is a real number.
If there is a strong cross wind the shooter aims left or right of the target.
In this case the velocity is represented by a complex number and is the vector sum of the cross wind velocity which is an imaginary number and the velocity when shooting directly at the target which is a real number.
Regards
Steven