And I forgot...
May. 4th, 2005 06:28 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
labellementeuse... I learned something really interesting today! (audience: *gasps*) Yeah, yeah, shut up. This is actually interesting- or I think so, anyway. It was in Astrophysics, which was even more surprising. :p You know Dark Matter? Well...so Dark Matter is this theory physicists and cosmologists have come up with to explain these serious problems they're having with a whole range of problems, called the "Missing Mass Problems." These go from varying degrees of complicated; in class at the moment we're looking at the mass of the galaxy and its comparable rotational curve- don't ask me, I'm not entirely sure I understand it either. Anyway, I've heard a bit about Dark Matter, on and off, but the most interesting theory I've ever heard about it is the one presented to me today- apparently it's the pet theory of someone in the Department, David Wiltshire (I think.)
His idea, basically, is that the Missing Mass problems are not caused by actual, you know, invisible mass that we can't detect; that in fact, they're caused by our poor understanding. I think this pleased me most because of its comparision with various other science mysteries. Way back in the time of the Greeks, when received wisdom held that Earth was at the centre of the universe and the planets all orbited it in circular paths, the Ancients had a real problem in that they couldn't work out a way that the stars could orbit the Earth while still following the paths they appeared to in the night sky. In other words, the data didn't fit the theory. What they ended up doing was tweaking their ideas of the orbits to add lots and lots of little loops, because they couldn't conceive of elliptic orbits that did not centre at the Earth. They had the theory, and the data didn't fit, so they made something up to fill in the gap. This kind of thing happened- happens, even- all the time. It's most particularly interesting in the case of the Missing Planet, which was actually early-ish last century (I think.) Scientists had gotten used to plotting the orbits of the planets using Newtonian Mechanics, which indeed proved to be very accurate for the orbits of Earth, the Moon, Jupiter, Saturn, and so on and so forth. But when measurements got very good, it was discovered that mercury- which is right up next to the Sun- and Uranus- which is a long way away from the sun- didn't quite fit the Newtonian orbit predicted for it. This caused something of a kerfuckle in astronomy, and eventually it was decided that the variations in Mercury's orbit must have been caused by another, undetected planet, named "Vulcan." Astronomers hunted for this planet for ages and ages, right up until Einstein came along with his Theory of General Relativity, which showed that it wasn't that there was an extra, invisible planet- it was that Newtonian mechanics were not accurate for Mercury (to do with its proximity to the Sun's great mass, IIRC.) In other words, just like the Greeks, physicists had actually made something up to cover for the inaccuracies of received wisdom, because they couldn't see, or rather didn't know, that Newtonian mechanics were incomplete.
So this is the theory... that Dark Matter is just something made up to cover for the vagaries of, rather than Newtonian physics, the General Theory of Relativity. Isn't that a cool idea?
... no? Well, I think it's awesome. ;)
His idea, basically, is that the Missing Mass problems are not caused by actual, you know, invisible mass that we can't detect; that in fact, they're caused by our poor understanding. I think this pleased me most because of its comparision with various other science mysteries. Way back in the time of the Greeks, when received wisdom held that Earth was at the centre of the universe and the planets all orbited it in circular paths, the Ancients had a real problem in that they couldn't work out a way that the stars could orbit the Earth while still following the paths they appeared to in the night sky. In other words, the data didn't fit the theory. What they ended up doing was tweaking their ideas of the orbits to add lots and lots of little loops, because they couldn't conceive of elliptic orbits that did not centre at the Earth. They had the theory, and the data didn't fit, so they made something up to fill in the gap. This kind of thing happened- happens, even- all the time. It's most particularly interesting in the case of the Missing Planet, which was actually early-ish last century (I think.) Scientists had gotten used to plotting the orbits of the planets using Newtonian Mechanics, which indeed proved to be very accurate for the orbits of Earth, the Moon, Jupiter, Saturn, and so on and so forth. But when measurements got very good, it was discovered that mercury- which is right up next to the Sun- and Uranus- which is a long way away from the sun- didn't quite fit the Newtonian orbit predicted for it. This caused something of a kerfuckle in astronomy, and eventually it was decided that the variations in Mercury's orbit must have been caused by another, undetected planet, named "Vulcan." Astronomers hunted for this planet for ages and ages, right up until Einstein came along with his Theory of General Relativity, which showed that it wasn't that there was an extra, invisible planet- it was that Newtonian mechanics were not accurate for Mercury (to do with its proximity to the Sun's great mass, IIRC.) In other words, just like the Greeks, physicists had actually made something up to cover for the inaccuracies of received wisdom, because they couldn't see, or rather didn't know, that Newtonian mechanics were incomplete.
So this is the theory... that Dark Matter is just something made up to cover for the vagaries of, rather than Newtonian physics, the General Theory of Relativity. Isn't that a cool idea?
... no? Well, I think it's awesome. ;)
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