Posted by
Rob on Monday, August 24, 2009 2:39:11 PM
I'm a little behind on my blogging here, with so many interesting stories to cover in the past few weeks, I've been storing them on my desktop. Today I'm cleaning house, and decided on some short blogs to clear them out.
One commentator read the lengthy
comet-life debate, and asked about "
Plasma-Cosmology" and the attempt to find alternatives to the Big Bang. Well, to begin with,
Hannes Alfvén wasn't trying to start a new cosmology with his discussion of plasmas (ionized gas), he was trying to revive an old one. Like Sir Fred Hoyle who coined the pejorative "
Big Bang" he was resisting the new-fangled fascination with
cosmic microwave background (CMB) radiation,
and attempting to explain the data with the more atheist-friendly "steady-state" universe theory. He didn't succeed, in part because Alfvén never really had a
comprehensive theory, merely an objection to the way astrophysicists ignore plasmas.
And judging by the referee comments on my one and only astrophysics proposal, they still do.
So what are some of the cosmological consequences of ignoring plasmas?
Here's my list of Alfvén-like objections:
a)
Big Bang Nucleosynthesis (BBN) is the process by which hydrogen, helium and a smattering of Lithium were made in the primordial explosion. Along with the CMB, it is the principal evidence for the BB. But the era in which plasmas dominate is treated as if it were a wet-chemistry experiment. There are no long-range forces, and no provision for plasma instabilities. Should such instabilities exist, it would shift the equilibrium away from deuterium-tritium, and possible explain how heavier atoms like lithium, beryllium and carbon were made in the "dark ages" when light could not penetrate the plasma. And should sufficient carbon/oxygen be made in the BBN, then it would form the baryonic "
dark matter" that is presently unexplained, hiding it in black, boulder-sized comets. The paradox being that current BBN models underpredict the baryonic component of the universe (atoms) leaving theorists to postulate "exotic" forms of dark matter, such as MACHOs and WIMPs. All this may be solved by putting in the plasma physics where it belongs.
b) The engine at the center of
astrophysical jets remains a mystery. From a physics viewpoint, it really is an engine, with unspecified potential energy going in , and kinetic energy coming out. Now a heat engine is a particular type of engine, taking the random incoherent motion of heat and tidying it up by having coherent motion coming out. In the case of a car, it is the coherent motion of the driveshaft, at much lower velocities than the hot exhaust molecules in the pistons. In the case of a gun or a rocket, the projectile has nearly the same velocity as the gas molecules. And in the case of a linear accelerator, the projectiles are at much higher velocities than the electrons travelling through the cables. In all of these cases, we can compare the energy in the projectile to the energy in the fuel, and calculate an efficiency. A gasoline engine is about 25% efficient, a gun about 2%, and a linear accelerator too small to calculate, <0.001%. So when an astrophysical object pumps enormous energy into a beam of accelerated particles with no obvious linear accelerator or powerplant nearby, we want to know how it does this magic that we cannot duplicate on Earth. The astrophysical answer has been "black holes", which is to say, "hidden under the rug". A better answer might be "plasmas".
c) And this brings up the whole notion of
black holes. A Big Bang and a Black Hole are really the same object, theorists claim, the one going forward in time and the other backward. So if BB is a fiction, then probably so are BH.
Several theorists have argued that we really don't need BH in our cosmology,
that all the effects of a BH can be constructed out of a very hot, dense and magnetically
constrained plasma, with radiation pressure holding the entire thing together.
It's an intriguing concept, which may explain why jets are seen equally for young stellar objects,
microquasars, neutron stars and galactic black hole candidates.
But if a plasma could simulate a black hole, could a plasma simulate a big bang?
The authors don't say. Maybe Alfvén was once again, more right than he knew or
deserved.
There is another connection between Big Bang and Black Holes,
with some surprising results that suggest once again, we need to revisit the physics,
for it would appear that perhaps there is one thing that black holes can't destroy, and big bangs can't create...
Information.
To be continued...