The Short Answer: (If you don’t read anything else, read this)

Using the force of gravity, astrophysicists predict the existence of a “dark matter” particle. It would make their math work out correctly. Particle physicists predict the existence of a particle with the EXACT same characteristics as the “dark matter particle,” but their predictions are based on the strong and weak forces – which are completely independent from gravity.

The Story and Explanation:

Up until June 2008 I didn’t believe that dark matter was really the best explanation for the inaccuracies that lead to the theory of dark matter. So at the American Astronomical Society conference I went seeking someone who could convince me that dark matter really was the best theory. I found someone.

Why Dark Matter Was Proposed:

You can calculate the mass of things in space based on how they move. You can also look at things in space, and knowing what they’re made of, you can total up what you think they should “weigh” based on how much stuff you can see.
When you weigh a galaxy based on motion you get a mass that’s double or more what you get when you total up the mass of all the the stars, dust, gas, and black holes that you think are actually there. Obviously there’s something missing, something you can’t see. This invisible stuff is called “dark matter.”

Why I Liked Modified Newtonian Dynamics (MOND):

I believe in human fallibility. We’ve gotten so much physics so wrong in the past (We used to think the Earth was the center of the solar system!), that the simplest answer is probably that we just don’t know all the laws of physics yet. Why believe that there’s invisible stuff in the universe, when you can just change the math?
That’s what MOND says: we’re doing the math wrong. If you change the math in a certain way, it matches our observations better, and you don’t need some mysterious invisible matter. MOND’s specific way of changing the math works for galaxies, but it doesn’t apply to anything else. In fact, it makes that math for other physics not work very well at all. So, I agree, MOND itself is wrong, but maybe there’s another change we could make to the math instead.

Bullet Cluster (blue is dark matter, pink is gas) Credit: NASA/CXC/CfA

What Convinced Me:

There is another, simple change you can make to the math to make it work: add a “dark matter particle.” If you account for these particles in your math, everything works. Yeah, pretty much everything.
More importantly particle physicists have also predicted the existence of a “dark matter particle.” Particle physicists are doing completely different math than astrophysicists. Astrophysicists use gravitational force and electromagnetic force (light) to do all their observations and calculations. Particle physicists are working on a different scale: they can have laboratories and manipulate particles, and the elementary forces they study are the strong force and the weak force. This means that they independently came up with the need for a “dark matter particle.” They weren’t even solving the same equations. They were truly independent.

Paul Sutter, the grad student I was speaking with says, if they fail to detect dark matter particles with the Large Hadron Collider within the next 10 years, then the theory should be reexamined. Until then, it’s pretty likely.

Want More?

Bullet Cluster
About Dark Matter
LHC and Dark Matter

Where’d I Get My Info?

I spoke with a grad student, Paul Sutter, at the University of Illinois who is studying dark matter.

I’m long overdue for a post on my new agreement with (or is that understanding of?) the theory of dark matter. I promise I’ll work on it, but till then, here’s a hilarious music video of a new rap song about Cern’s new LHC (Large Hadron Collider)

The beginning is great, then you may start to feel like it’s dragging, but if you last through the first 3 minutes or so, you’ll get an pretty cool explanation of this “Higgs” that everyone is talking about.

Found it on BoingBoing.
Did you like that? Here’s more from AlpineKat.

For this week’s AstroInfo I’m going to answer a set of questions posed by youth who are currently training to offer space-related interactive activities out among the Pacific Science Center’s exhibits. In several places I express my personal opinion – which you should note is NOT the same as fact.

When can the general population go into space without paying a lot of $?
Who knows, maybe 10 years? Maybe two years, maybe 50? There is a competition called the “X Prize” that’s trying to jumpstart space travel (and other sciences). Until a couple years ago, no new spaceships for carrying people had been invented since the Shuttle. The Ansari X-Prize (http://www.xprize.org/x-prizes/ansari-x-prize) offered $10 million dollars to anyone who could “launch a spacecraft capable of carrying three people to 100 kilometers above the earth’s surface, twice within two weeks.” Burt Rutan and company completed the task on October 4, 2004 – after spending more than $100 million creating SpaceShipOne (go to the Museum of Flight to see a mock-up of it). This should push the space-travel industry along a little faster.

How plausible is human colonization of Mars/Moon in the next 50 years?
My opinion: It’s not. I say that because you used the word “colonization” which I think will take a long time. Right now there’s a plan to send humans back to the Moon and eventually to Mars, but just to visit.
The program is called the Constellation Program and it has three components:

• Orion Crew Vehicle – like the current shuttle
• Ares Launch Vehicles – rocket to carry the Orion
• Altair Lunar Lander – landing people on the Moon

How do they come up with the ideas for finding stars or researching about stars?
What usually happens is that someone notices something strange about a star or something else, and they decide to find out what’s happening. A simple example is a variable star. Someone studying a variable star would notice that on different nights it appeared brighter or dimmer. Then they would want to find out why – is there something traveling in front of the star? Is the star flashing or pulsing? Is the star spinning, and is one part brighter than another? Any of these might affect brightness.

Is there intelligent life outside Earth?
Not that we’ve detected. My opinion: yes.

Does dark matter exist?
Most scientists believe so. Though the evidence is pretty overwhelming, I’m not quite ready to believe it. Redacted as of 6/4/08.

What elements are found in the gases on Uranus?

Edited as of 6/6/08: The atmosphere of Uranus has Hydrogen (mostly), Helium (a little), Methane (a trace), Water (a trace), Ammonia (a trace). The methane, water, and ammonia are all aerosol ices – suspended crystals of ice (not ice cubes or blocks of ice). A later AstroInfo will explain Uranus in more detail. I was embarrassed to realize at the Spring 2008 meeting of the American Astronomical Society that what I thought I knew was significantly wrong.