Slashdot Mirror
Lasers Approach Their Ultimate Intensity Limit
Flash Modin writes "Death Star style superlasers? Don't bet on it. High-power lasers currently in development appear to be nearing the theoretical laser intensity limit, according to new research set to be published in the journal Physical Review Letters. Ultra-high-energy laser fields can actually convert their light into matter as shown in the late '90s at the Stanford Linear Accelerator (SLAC). This process creates an 'avalanche-like electromagnetic cascade' (also known as sparking the vacuum) capable of destroying a laser field. Physicists thought it might be a problem for lasers eventually, but this work indicates the technology is much closer to its limit than researchers believed. A preprint is available here."
In a nuclear explosion, there are fewer atoms around.
That depends entirely on the nuclear bomb. Fission weapons work by splitting uranium and/or plutonium into smaller atoms, at least doubling the number of atoms hanging around. Fusion weapons would result in fewer atoms, if they did not use fission triggers.
When our name is on the back of your car, we're behind you all the way!
True, but if you could actually measure the mass of the butane molecule with enough precision, you would find that it is more massive than the constituent atoms alone. This extra mass (m=E/c^2) is actually due to the potential energy stored in the bonds.
Unfortunately, that opening paragraph is horribly written. The rest of the entry is better, and gives an accurate though terse description of the problem. Before the 1940s, many aeronautical engineers believed -- quite rightly, givem the technology of the day -- that they couldn't design a plane that would hold together while passing Mach 1. Nobody ever claimed that it was physically impossible to fly faster than sound, and of course such a claim would have been absurd given that there were plenty of examples of things that did just that (e.g. bullets.) Serious attempts to build a supersonic airplane began in the 1930s, and by the start of WW2 everyone working in the high-performance aircraft field knew it was possible, they just didn't know exactly how to do it.
In short, it was an engineering problem, not a scientific one. This is completely different from limitations which are founded, as far as we can tell, not in the state of technology but in the laws of nature.
If out current understanding of the limiting natural laws turns out to be wrong, great -- I'd love to see a Death Star just as much as any nerd would. But don't bet on it. The fact that the X-1 flew no more means that we'll someday have faster-than-light starships with planet-destroying laser weapons than the existence of the internal combustion engine implies that perpetual motion machines are right around the corner.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.