Light One Candle

It isn't likely a surprise that someone who follows RDBMS and quants generally might also keep track of other science vectors. Fact is, my favourite TeeVee show is "How the Universe Works". These endeavors have made a bit of noise recently about the asymptote of progress, particularly the normal macro-world of science and engineering. There was a report (I didn't save a link, sniff) complaining that the younger generation hasn't been starting businesses as vigorously as previous ones. Of course; there's fewer actually new stuff out there on which to base a new venture. Hewlett and Packard started a business to do that which hadn't before existed. They could do that because science and engineering were digging out new discoveries. When new knowledge becomes scarce, so too do new ventures.

The nano-world and supermacro-world remain more unknown, however. But, however, the knowledge and discoveries in those worlds, the latter specifically, aren't likely to have immediate impact on our daily life in the macro-world. I made up supermacro-world. The standard term is cosmology, the study of the greater universe.

One of the main concerns of cosmology is the fate of the universe. The debate has been going on forever, but in earnest since Einstein. There are three possibilities: the universe is space, commonly conceived as a sphere, which is fixed or static; the universe is expanding at a fixed velocity; the universe is expanding with acceleration. The static universe was the accepted norm until Hubble calculated the red shift of distant objects. Then, the expanding universe was accepted. It wasn't until 1980 (yes, not that long ago) that accelerated expansion was proposed.

With any kind of expansion, the question becomes: what happens in the end? Does the universe expand to the point that matter exists in infinitely small density, with inevitable dispersion of energy to zero density? Or does the expansion eventually slow enough for gravity to halt expansion, and generate another big bang? The former is generally agreed to.

But, being just a semi-talented amateur, I've always wondered whether the cosmologists have been correct. The whole ball of wax rests on a single assumption: that physicists can actually measure the speed at which galaxies and such move. You can't just take out your standard issue police radar gun and point it at the Andromeda galaxy and read off the speed. How is it done? The answer is the standard candle.

Almost all astronomical objects used as physical distance indicators belong to a class that has a known brightness. By comparing this known luminosity to an object's observed brightness, the distance to the object can be computed using the inverse square law. These objects of known brightness are termed standard candles.

Of course, that assumes that we know how bright, in absolute terms, an object is; and that we know, by some other means, exactly how far that object is from us. If we know those two values, then we can compare it to measurements of other objects, do some arithmetic, and get distance, velocity, and acceleration. I've always been skeptical that physicists could actually do that.

Well, turns out, even the professionals have worried about that. We may not know quite as much about the supermacro-world as we thought. In particular, if the universe isn't actually accelerating, then we don't have to posit dark matter and dark energy and the like to balance the equations. Balancing the equations requires, just as it did in Newton's day, a source of power to drive the acceleration. In other words, cosmology may have invented a phenomenon in search of a requirement.

But measuring it requires divining the distances of lights in the sky -- stars and even whole galaxies that we can never visit or recreate in the lab. The strategy since Hubble's day has been to find so-called standard candles, stars or whole galaxies whose distances can be calculated by how bright they look from Earth.

We need a cosmic radar gun. Note that the article doesn't question the current view of acceleration. That's all mine. And, of course, there's no immediate effect on our macro-world. Even with accelerated expansion, the end is trillions of years away. Don't change your vacation plans.