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QUESTION: What is the smallest scale at which the force of gravity has been measured or detected, in terms of the total masses and densities involved? And, conversely, strictly in the world of mathematics, does the force of gravity exist in any degree at a quantum level? If so...where? What conditions?
ANSWER: Wow...the scope of the questions....
The smallest scale at which the force of gravity has been described is a matter of some debate. There are our high-energy particle accelerators which describe matter at very tiny length scales. There also exist sub-millimeter direct gravitational attraction experiments. So, depending on the physics being explored, everything from the 10^-18 meter scale to the 10^-3 meter scale has been looked at. The masses and densities vary by ridiculous values.
The world of mathematics doesn't dictate whether or not gravitation is quantized. That's a matter for physics. The journal of quantum gravity was headquartered on the same hallway I was a 2nd year grad student, so I'm aware of the relevant issues here. No one has quantized gravitation. At some point we know that gravitation and QM can't coexist, but we're not to the point where we can judge one over the other or determine how they fit.
If you need more details, ask a follow-up.
---------- FOLLOW-UP ----------
QUESTION: Just as a bit if clarification, by "quatized" you, I take it, are in reference to giving (or finding) the most basic/standard particle or media by which gravity would act in the quantum world, right? I mean, the "graviton" I believe has been theorized here, but not very successfully examined because it is so difficult to find/detect. This part of the dilemma of "quantizing" that we have yet to accomplish, is it not?
That is basically what I mean, yes. Also, the lack of observation of the graviton is indeed one major difficulty in coming up with a theoretical description of quantum gravitation. Hopefully spacecraft-based interferometers such as LISA (http://lisa.nasa.gov/) will shed some light on the subject.
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| Comment | These are some questions ya can't get answered just anywhere. lol You were extremely helpful in shedding a bit of light on this. Thank you very very much. You are an eloquent and knowledgable fellow. Is it frowned upon to have correspondance outside of the site? Encouraged? lol It would be very nice to get to know an intelligent and versed individual like yourself. If you get any time at some point, my email is cullyomeara@aol.com. (Dunno if you can just see it or if it's hidden on the site) But, I want you to know that it was very difficult to find the right place to get that answered in a timely manner, and without wading thru "questions of the week." And, it's been plaguing me for some time. Thank you very much, friend. (I'll be recommending you for volunteer of the month) =) | ||
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Steve Nelson
Expertise
Fusion, solar flares, cosmic rays, radiation in space, and stellar physics questions. Generally, nuclear-related astrophysics, but I can usually point you in the right direction if it's not nuclear-related or if it's nuclear but not astrophysics.
Experience
Currently a physics professor at the University of Texas of the Permian Basin. Doctoral dissertation was on a reaction in CNO-cycle fusion, worked in gamma-ray astronomy in the space science division of the naval research laboratory in the high-energy space environment branch.
Organizations
Physics professor at the University of Texas of the Permian Basin.
Education/Credentials
Ph.D. in physics, research was on nuclear fusion reactions important in stellar fusion.
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