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Lasers Approach Their Ultimate Intensity Limit 384

Posted by samzenpus
from the biggest-pointer dept.
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."
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Lasers Approach Their Ultimate Intensity Limit

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  • by Anonymous Coward on Wednesday August 11, 2010 @03:29PM (#33219386)

    Burning lighter fluid is a chemical reaction, the same amount of matter exists before and after, it just exists in new compounds. Nuclear explosions actually destroy matter.

  • Re:Limits? Ha! (Score:3, Insightful)

    by VisiX (765225) on Wednesday August 11, 2010 @03:32PM (#33219440)

    Limits are made to be broken.

    The opposite of this is true.

  • Re:Limits? Ha! (Score:3, Insightful)

    by SilverHatHacker (1381259) on Wednesday August 11, 2010 @03:46PM (#33219650)
    Everything that can be invented has been invented.
    The telephone has too many shortcomings to be seriously considered as a means of communication.
    640k ought to be enough for anybody.
    Turns out nobody can ever predict the future of technology (except maybe Orwell, but no one wants to admit that).
    Just because we can't think of any way to break this "theoretical limit" doesn't mean it can't be broken. I'm sure at one time they said it was impossible to go faster than sound.
  • by camperdave (969942) on Wednesday August 11, 2010 @03:50PM (#33219726) Journal
    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.
  • Fascinating (Score:3, Insightful)

    by wikdwarlock (570969) on Wednesday August 11, 2010 @03:56PM (#33219804) Homepage
    Anything that requires 47 billion eV electrons and a 1 trillion watt laser has to be freaking amazing to be a part of.

    Yay Science!
  • Re:lighter fluid. (Score:3, Insightful)

    by Hatta (162192) on Wednesday August 11, 2010 @03:59PM (#33219846) Journal

    If you count all the protons, neutrons and electrons before and after the chemical reaction, they're all still there.

    But the mass is not.

  • by Vectormatic (1759674) on Wednesday August 11, 2010 @04:01PM (#33219864)

    No, it is stored in chemical bonds, not in the form of matter

    unless you believe you actually lose weight when falling of a building, because some of your matter is converted into kinetic energy..

  • Re:Limits? Ha! (Score:1, Insightful)

    by Anonymous Coward on Wednesday August 11, 2010 @04:02PM (#33219876)

    Everything you mention is about the limits of technology. We're talking about the limits of physics. No one has reversed entropy, surpassed the Carnot efficiency, or gone faster than light. If this is indeed a theoretical limit, then it's a lot less likely to be broken than something like sound barrier, which was always understood by physicists to be a purely technological difficulty.

  • by SirRedTooth (1785808) on Wednesday August 11, 2010 @04:05PM (#33219902)
    We can still fire objects into planets at faster than light speed. Theoretically. (You know the whole move space but not the object thing?)
  • by Anonymous Coward on Wednesday August 11, 2010 @04:08PM (#33219956)

    If you could track every atom of the lighter fluid, you'd see that there are as many atoms from the lighter fluid around after the combustion as before. In a nuclear explosion, there are fewer atoms around.

    In a theoretical pure fusion explosion, yes. In a fission explosion there are quite a few more atoms. In a fission-boosted fusion bomb, there are almost certainly more atoms overall than you started with because the majority of the energy still comes from the fission of nuclei. In all cases what has decreased is the binding energy between the protons and neutrons in the atoms.

  • by Carnildo (712617) on Wednesday August 11, 2010 @04:31PM (#33220438) Homepage Journal

    Didn't you read the summary? "Ultra-high-energy laser fields can actually convert their light into matter" -- this means that sufficiently powerful lasers can create their own frickin' sharks.

  • Re:lighter fluid. (Score:5, Insightful)

    by smaddox (928261) on Wednesday August 11, 2010 @04:43PM (#33220672)

    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.

  • by Anonymous Coward on Wednesday August 11, 2010 @04:43PM (#33220674)

    Chemical bonds are matter, just as much as nuclear bonds are. It's a marvel of the universe.
    I think you'll also find that, seen from your immediate surroundings, you gain mass as you fall off the building and your velocity increases. Though you'll also briefly experience weightlessness, so I suppose it's not wrong to say that you lose weight.

  • Re:Fascinating (Score:1, Insightful)

    by Anonymous Coward on Wednesday August 11, 2010 @04:58PM (#33220948)

    That all depends on where you are when they fire it off...

  • Re:Limits? Ha! (Score:5, Insightful)

    by Daniel Dvorkin (106857) * on Wednesday August 11, 2010 @05:17PM (#33221316) Homepage Journal

    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.

  • by Anonymous Coward on Wednesday August 11, 2010 @05:23PM (#33221450)

    Why not? Trillions of parallel lasers of "near ultimate" power will surely cause a rukus at whatever planet you zap with it.

  • by ChronoReverse (858838) on Wednesday August 11, 2010 @05:54PM (#33221902)
    I'm pretty sure relativity doesn't work that way.
  • by Chris Burke (6130) on Thursday August 12, 2010 @01:21AM (#33225160) Homepage

    Energy is matter, matter is energy, it must be in one form or the other

    Matter is a different thing than mass, and much more difficult to define. Energy is mass and mass is energy, and it's not that it must be one or the other, they are literally the same thing. Matter is generally things we consider to have rest mass, which isn't the same as mass. Rest mass is a form of energy (and thus mass, duh).

    What you said about butane is right; it's heavier. It's not that there's more matter, but there is more mass, i.e. energy.

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