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Most Detailed View of Dark Matter Mapped By Hubble
astroengine writes "Building on previous studies by the Hubble Space Telescope, new analysis of gravitational lensing data has revealed the most detailed map of the distribution of dark matter yet. The distribution appears as a beautiful ghost-like or ethereal haze and could have serious ramifications on our understanding as to how galaxy clusters form and evolve."
TFA is firewalled off, but I found a better FA -- straight from NASA's JPL. here is a hi-res photo of the "dark matter" lensing.
Free Martian Whores!
I'm just asking the question, because I don't have a great deal of knowledge about this, but could an alternative explanation be that our theory of gravity is wrong?
Kind of.
In all other experiments, our understanding of Gravity works just fine. In this one situation however, it does not. Someone proposes the idea of Dark Matter - which fits the bill almost perfectly, as it accounts for what we've seen.
Alternatively, our understanding is wrong. We don't know how its wrong, or why its wrong, it's just not working. When we look at hundreds of other examples, it works. When we look at this one, it doesn't.
Is it more plausible to discount our theory based on the 1 case where it doesn't hold up, or assume there is something special about that one case that seperates it from the others.
Thats why Dark Matter holds some water. But - by all means, it is entirely possible that we don't have it quite right, we could be missing some variables that simply are negligable at a non-cosmic scale.
God: Bender, being God isn't easy. If you do too much, people get dependent on you, and if you do nothing, they lose hope. You have to use a light touch. Like a safecracker, or a
Bender: Or a guy who burns down a bar for the insurance money!
God: Yes, if you make it look like an electrical thing. When you do things right, people won't be sure you've done anything at all.
I just pooped your party.
I just learned that Allan Sandage died this weekend. He was a giant among astronomers and did a lot of work with the Hubble. Take some time and learn about him if you care about astronomy http://en.wikipedia.org/wiki/Allan_Sandage
but could an alternative explanation be that our theory of gravity is wrong?
Yea. The discovery is that, IF our theory of gravity is correct, this is more evidence for the existence of dark matter.
It is something more along the lines of this:
We have a good number of formulas and calculations that work properly with the things we can measure - planets, the sun, cars, planes, kitchen scales.
One of these might be:
y + 3 = 5
Nice and simple for this example. Lets say that the "y" here represents gravity and the formula has been proven in every experiment we have done.
We therefore assume that this calculation is correct and true. BUT when we try to use this calculation when looking at things like galaxies, we seem to find the wrong answer:
y + 3 = 7.2
This is clearly not correct, but as we don't want to throw out all the formulas and understanding we have about how things work, we add another variable to the formula like so:
y + 3 + x = 5
The "y" still represents gravity, but now we add the "x" which represents something we don't understand and we don't know where it came from. We call it Dark Matter because we can't see it, don't seem to be able to interact with it and have no real idea of what it is - but with this new addition to the formula, the answer once again comes out at what we know (think) to be true. We just now need to find what this x variable is.
THAT is why finding/understanding Dark Matter (and on that note, Dark Energy) is so important. We know (think we know) the right answers, but our formulas just don't seem to fit so well when applied to certain really, really, really big things (like clusters, superclusters etc). When we find this "x" in the formula, it will once again work perfectly for all our calculations.
Moved to http://soylentnews.org/. You are invited to join us too!
Long answer: Dark matter wasn't invented just because someone saw some anomalous behavior that didn't agree with theory, and said to themselves: "Oh, there has to be something mysterious at work here, we'll call it dark matter.". There are several reasons for believing in dark matter, for example that when measuring gravity we notice gravity coming from directions where we can't see any matter. However, the source of this gravity behaves a lot like matter would. For example we can observe these "invisible gravity sources" being thrown around when two galaxies collide. Because these "invisible gravity sources" acts a lot like matter, except for the fact that we can't see it, it's called dark matter.
If you're not yet convinced, take a look at this recent blogpost by a professional astrophysicist: http://scienceblogs.com/startswithabang/2010/11/the_simplest_argument_for_dark.php In this post, he basically explains how we can derive the existence of dark matter from: A) Assuming that the theory of general relativity is valid, B) assuming that the big bang theory is valid, and C) our observations of the cosmic microwave background.