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Old June 5 2013, 07:23 PM   #88
Crazy Eddie
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Re: Strange Dark Matter Theory

FlyingLemons wrote: View Post
Crazy Eddie wrote: View Post
His reply was exactly this: GPS satellites do not really account for relativistic effects because they don't have to: their onboard clocks re-synch periodically through ground stations to keep them coordinated with both the Earth clocks and one another.
That's the GPS system recalibrating the satellite clock from the ground station to take into account the time dilation that would occur if the satellite clock were left to its own devices.
That's kinda what I mean. The satellites aren't programmed to account for relativistic distortions; they re-synch manually via ground stations. The claim that the satellites have a corrective subroutine that accounts for relativistic effects is more legend than fact. Besides which, the accrued error due to time dilation alone would be relatively small even if it wasn't corrected.

Crazy Eddie wrote:
Theoretical physicists have become so enamored by the possibilities of dark matter that derivative theories about what it could be and what it could DO extend far beyond any logical connection to the data that suggests its existence...
Uh... not really. The media would like to portray it that way, but in actual fact there are quite a few interesting debates going on surrounding that area.
And I've been following enough of those debates to know that several of them are debates between theorists over the nature of the derivative theories and their broader implications in cosmology. Always in such cases I get the sense that theorists are getting way ahead of themselves, debating the properties of something that has not yet been proven to exist in the first place, which explains why alot of those debates bear a rather disturbing resemblance to arguments between Trek fans over the nature of warp drive. In the complete absence of data, otherwise rational scientists begin to substitute personal bias and unsupported assumption in its place. When their peers blow those assumptions out of the water, suddenly it gets personal.

Have you ever tried submitting a paper to Nature, PRD or JHEP? The reviewers there tend to be absolutely merciless if they find a mistake in your math - in my experience papers need to be mathematically watertight to get through at least for those journals. As iguana pointed out, physicists are pretty cut-throat and don't shy away from criticizing each other's work.
I know that, but at the same time it goes both ways. If you construct an equation of great enough sophistication that nobody can actually tell what you did wrong, it becomes easier to attack the credibility of people who disagree with you. Which, again, is pretty much what happened with Reinhart and Rogoff's austerity study until somebody actually dug into the numbers and found them to be bullshit after all.

Uh, what? Where'd you pick this up?
From conversations with a friend of mine working in Fermilab, although I should clarify that this is less a problem with the theorists and more a problem with institutions that fund them (universities and government agencies, for example). This is where politics and the scientific method begins to clash, which is DEFINITELY a relationship that scientists are understandably uncomfortable talking about.

There's plenty of us thinking about modifications and extensions to the theory of relativity because of the wealth of observational data in particle physics and cosmology telling us that something's not quite right with regards to the cosmological constant and high-energy behavior of gravity.
I know, and I'm familiar with a lot of them too. MY personal bias (call it a pet theory) is that Einstein's interpretation of the implications of Lorentz contractions introduced some potentially unwarranted conclusions and there is actually no need to extend the theory beyond Minkowski spacetime. I think that General Relativity would work a lot better if a way could be found to systematically apply Lortentz transformations to a curved spacetime -- say, Minkowsky spacetime with a noticeable curve -- at which point the distinction between special and general relativity disappears.

I'm a particle physicist
I'm a skeptical asshat who reads too much. Pleased to meet you!
Then there's one area I've worked in: that of the application of renormalization group. RG allows the constants of a quantum field theory to become subject to an energy scale, and allows us to vary said constants and study how the phenomenology of the system is affected by this.

Applying it to gravity, you can treat the theory of general relativity as an effective field theory and allow G and lambda to vary from the Planck era. This is quite interesting as some work by Percacci indicates that we could get inflation, reheating and the cosmological constant for "free" rather than through the introduction of new, unknown scalar fields.
I'll update my reading list for the weekend. Thanks for the tip!
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