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posted by
Dopefish
on Sunday February 23 2014, @08:00AM
from the where's-carl-sagan-when-you-need-him? dept.
from the where's-carl-sagan-when-you-need-him? dept.
pjbgravely writes:
"Scientists use gravity lensing measurements to determine mass of galaxy clusters. Anja von der Linden, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California, is using the Subaru telescope and the Canada-France-Hawaii telescope, both on Mauna Kea in Hawaii. The results are 40% higher than the measurements done by the Planck collaboration.
I guess there goes Douglas Adams' theory that the missing mass was in the packing material of the scientists' equipment."
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(Score: 3, Interesting) by evilviper on Monday February 24 2014, @12:42AM
Well OF COURSE it fits observations. It was a theory created to fit the discrepancy between accepted theories and actual observations. That just shows the discrepancy is uniform, but not really proof of anything by itself.
I wasn't trying to suggest MOND or some other existing theory is accurate, just that dark matter and dark energy are a "fudge factor" without a firm theoretical basis, nor any evidence or observations seen on a local scale.
I'm not opposed to it being found and quantified, but in the mean time, it's just a bit of a stretch to assume that a fudge factor is a real, physical object floating around in space, even if it might be.
Hydrogen cyanide is a delicious and necessary part of the human diet.
(Score: 1) by khchung on Monday February 24 2014, @01:52AM
You wrote this as if our current theories are just a bunch of curve-fitting functions with a whole bunch of free parameters we can tune. The truth cannot be farther than that!
What makes the current physical theories "beautiful" is the fact that these theories often start with very simple and clear premises, and then much of everything flows logically from them, with almost no room for tuning or "fudging".
Take Special and General Relativity as example, the premises "Every observer is the same", "the speed of light is constant for everyone", "you cannot distinguish between an accelerating lift and a lift in gravity", etc, are all either measurable, or would make the universe quite incomprehensible if wrong ("every observer is the same"). Then you work out the math and got the equation, and if observation did NOT fit, BAM! the theory is wrong.
If the precession of Mercury was not exactly what GR predicted, there is nothing else you can play with without causing it to fail in other areas.
Sure, you can postulate that it was GR that was wrong instead of the existence of some dark matter. But until you can come up with another theory of gravity that worked as well as GR AND do away with dark matter, then having one workable theory (GR) + one unknown (dark matter) seems better than having no workable theory at all.
(Score: 1) by evilviper on Monday February 24 2014, @12:38PM
It doesn't have to invalidate the entire theoretical basis of GR/SR, just because the equations need a fudge factor to work. Just consider the Cosmological Constant... Or consider how it falls apart with black holes or other quantum phenomena.
It's not an either-or. You can keep using it, but you should acknowledge that there seems to be something "wrong", rather than acting like it's an entirely solved problem. Think of Newtonian mechanics before GR... Nobody invented exotic new theoretical types of matter to make the equations match more closely than they do.
Better yet, just TRY to consider the possibility that in the next couple decades there will be numerous experiments trying to identify and study dark matter / energy, and it's possible they'll all simply come back with a negative result. Then you still have numbers that work, but without the conceit that they might be theoretically sound.
Hydrogen cyanide is a delicious and necessary part of the human diet.