Dynamically Newton.

My Advanced Dynamics class will be pretty challenging. The difficulty will be worth it though just to hear my professor get super excited about Newton and Physics.

Let’s get geeky.

One thing the professor mentioned was Modified Newtonian Dynamics (MOND), something I had known nothing about. I decided to do a little extra research on the matter and share it with the world.

We’ve all heard of Dark Matter. The big reason Dark Matter is believed to exist is because galaxies act a little funny. Let’s first look at things that aren’t galaxies… take for example our solar system.

Mercury is close to the sun. Because of this, the sun’s gravity influences this little planet more than the sun influences… say… Neptune. As a results, Mercury rotates much faster around the sun than the rest of the planets. Not only does it follow Newton’s law F=ma, it just makes sense.

Unlike our solar system however, all bodies in a galaxy move around the center at about the same speed. This doesn’t make ANY sense. If gravity is huge and imposing at the center of the galaxy, it should be weak and pathetic at the edge of the galaxy. Until 1981, everyone had assumed that the only explanation of this would be if there was some mass that we didn’t know about that was adding some muscle to the weak edges. And thus DARK MATTER was born.

Dark matter, as Newton followers believe, forms a ring around the galaxy that equalizes the gravitational forces. The result is that all bodies in a galaxy would rotate at the same speed. ta-da! problem solved!!

Mordehai Milgrom, an Israeli physicist, was NOT COOL WITH THIS.

Milgrom suggested that perhaps when the acceleration of F=ma is really tiny, things get funky.

Tiny is relative of course… but when we’re looking at galaxies, tiny accelerations could be pretty substantial by our standards. So Milgrom suggested F=ma be changed to:

F= m u(a/a0)a

There’s plenty of data on that equation on the internet, so if you’re interested I would recommend checking out this site.

The problem with MOND, is that it’s extremely hard to TEST. This is because we can’t really deal with a scale big enough to make accelerations really tiny. So far all scientists seem to be able to do is observe OTHER galaxies and say “hey… that one has constant speeds too.”

11 thoughts on “Dynamically Newton.

  • 9/14/2006 at 8:05 am

    I don’t agree with the theory of dark matter either. I suppose it depends on whether the gravitational force of the universe is powered by external force or internal magnetism. I’m a little rusty on my scientific theories. TIme to crack open my college textbooks. I always did like physics.

  • 9/14/2006 at 8:52 am

    I am looking forward to tonight’s marketing class, actually.

  • 9/14/2006 at 10:25 am

    We should start a completely arbitrary “anti-dark matter’ campaign. We could picked at major political gatherings and see if we could get candidates to give us their opinion on the matter.

  • 9/14/2006 at 11:05 am

    Dark matter is bogus. This is the Aether all over again. I mean where else does something like this happen:
    Scientist 1: “This doesn’t make any sense.”
    Scientist 2: “Yes, we don’t understand how this works.”
    Scientist 1: “You know…this WOULD make sense if we just made something up that explained it perfectly.”
    Scientist 2: “Will people buy that?”
    Scientist 1: “Only if we give it a cool name.”

    Hooray for physics!

  • 9/14/2006 at 2:14 pm

    I’m a proponent of the “dull matter” theory. The extra matter is visible, but so boring no-one notices it.

  • 9/24/2006 at 11:32 am

    I’m with Roland. I have another theory with regard to the dark matter debate. It goes like this: Who gives a **bleep** ?!

    Something tells me my life will suck regardless of what the “experts” think. What is, is. Scientific theories do not change what already exists, they only change the perceptions of the impressionable/gullible. Life is a mystery for a reason, and probably a darn good one. Until such time as the mystery is supposed to be revealed, they should just leave sick enough alone.


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