Thirteen years after their independent discoveries that the Universe is expanding more rapidly than was first thought, three astronomers, Saul Perlmutter and Adam Riess of the United States and US-Australian Brian Schmidt, were awarded the Nobel in Physics. They theorize the ‘vacuum’ of space is actually full of ‘dark matter’ which acts as an anti-gravitational force that ‘pushes’ against gravity to speed the universe on to its eventual destruction in something less than a ‘Big Crunch.’ Instead the universe will ultimately die in a ‘Deep Freeze’ as suns get pulled away from their orbits and explode into novae and super-novae.
What does this discovery mean to physics as we know physics today?
One thing it means that a lot of work in physics will be done in developing more accurate long-range means of observation. This might mean better telescope, but it might mean some other means.
In order to pin down the details of what drives expansion, measurements that are as detailed as possible need to be worked out. Right now there is significant scatter in the data that astronomers get about the distant universe and it’s still too great to narrow down the details of dark energy.
However, if dark matter is shown–as it seems to have been through the work of the independent Nobel laureates–to be an antigravitational force, what does that do to Newtonian physics and could it be used to boost matter to speeds beyond the speed of light?
The equations governing dark matter are related to Newtonian equations considered some years after Newton. (They don’t exactly match up, but there are reasons for that.)
Long story short: in order to have a universe that wouldn’t collapse, introduce a gravitational force that repelled things at long range–eventually things balance. (This is essentially the same in the Newtonian case and the relativistic case.)
The end of that story is that in the long run things don’t balance, because if there is anything slightly off center, the universe still either collapses or expands.
But the equations, in the relativistic case, floated around in people’s minds and were still half-considered since 1917. (Is there a good history of this? Probably, the best is The Extravagant Universe by Robert Kirshner. Though Helge Kragh wrote a good academic book about the history—and also a bad one from about 2007.)
The dark energy component is so small that it doesn’t effect anything that we would normally use Newtonian gravity to calculate (which is up to the rotation of galaxies).
Weirdly, because it is a relativistic component of gravity, it doesn’t give galaxies a velocity. It only influences the distance between galaxies. A strange point, but important for relativity theory. The velocity of an object cannot be boosted beyond the speed of light, but the distance between two objects can increase at faster than light could travel between them. The distance between two points is a function of the energy density of the mass between and around those points, and the energy density of dark energy works opposite to the ordinary energy density and its effect increases with distance, whereas the effect of other energy densities decreases with the square of the distance.
I have to critique my own OP. It’s been theorized, based on independent findings, that there are ‘entities’ called neutrinos that move at a rate that’s faster than the speed of light. By reason of its label, it’s neutral in so far as it has no electrical or magnetic properties. No one knows what, exactly, a neutrino is.
No one knows what dark matter is, exactly. Physicists assume it’s there because of its assumed effect on other things physicists assume exist–no matter what ‘natural laws’ may be.
Dark matter hasn’t been ‘shown’ to be anything concrete, as far as I know. As a result, we have no real idea of it’s presence in the universe, or–to apply a human term–its utility.
Pondering things such as this is my way of exercising my mind. I’d love answers, but I expect only other ponderings.