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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."
Simply :(
Creating light from matter is rather ordinary in terms of physics, as can be seen in nuclear explosions
Or even running out of lighter fluid.
The SLAC experiment was just a singular event, but as lasers reach higher intensities the electric fields produced will increase as well and the team says that when they reach a critical intensity a cascade effect will occur as a result. The electron-positron pair is accelerated by the laser field itself at such high energies that they emit photons capable of spawning new pairs and continuing the process.
Maybe that's how the death star works? Besides, it isn't explicitly stated anywhere in the movies that the death star is a laser.
Also, they're not talking about a single laser, they're talking about colliding two laser beams.
Free Martian Whores!
Where are my sharks with laser beams then!?
Can anyone tell me why 99% of
Have they considered relabeling their laser intensity dials so they go up to 11?
We all know how avalanche-like electromagnetic cascades wind up.
"Death Star style superlasers? Don't bet on it."
Uh, you mean a bunch of laser beams that come out straight, stop for a fraction of a second, turn a few degrees and then join up and all go off in the same direction?
I wasn't exactly holding my breath for that, anyway!!
If Slashdot required a user name to consist of two capitalized words, we would see less about sharks in articles about lasers.
All this means is we need to be more imaginative with our designs. Limits are made to be broken.
Funny may not give karma, but +5 Informative never made anyone snort coffee out their nose.
If Half-Life taught me anything, it's that cascades can result in terrible and unforeseen consequences D:
Sorry, this is new to me. What kind of matter is created? Full atoms? Just neutrons or protons? Or nothing more than subatomic bits?
A slashdotter who didn't build his own computer is like a Jedi who didn't build his own lightsaber.
Can convert light into matter?
Sooooo PewPewPew, eventually becomes SplatSplatSplat?
That's an interesting kind of awesome right there.
Is there a theoretical upper bound to the maximum efficiency of converting energy into coherent light (lasing), other than the obvious "nearly 100%"?
What is the most energy efficient laser in production today, and how close to the theoretical max will lasers get within the next 5-10 years?
--
make install -not war
It should be clear that death star was not a laser, but a particle beam weapon,
http://en.wikipedia.org/wiki/Particle_beam_weapon
You can see in the following documentary, the beam speed was visible, hence it was not a laser.
http://www.youtube.com/watch?v=TpztVZWC_hk
Funny, I didn't read anything in the article about sharks.
Tell that to the guy that keeps Void Ray rushing me.
Waveform theory and the hard limit of the speed of light dictate a maximum power yield for laser output using the standard model.
Of course, the wave/particle duality of photons suggest that quantum mechanics may provide a means of upping this yield by observing enough quantum states in one stream of photons to "push" them into the other, theoretically approaching double the power (over 9000) of the initial laser. In practice this is unlikely due to collision unless the protons could be nudged back into a wave state as they reemerge in the initial laser.
As they say, when one door closes another one opens.
Everybody knows 'lasers' in Star Wars are actually superheated gas. The gas product is what they mine on Cloud City.
Henchman: "Professor, I've increased the laser's power to a new incredible limit, and something remarkable has happened. It is creating new matter! I can tune the beam to create any matter in any configuration we need!"
Professor: "Darn. We needed a big laser. Oh well, throw it all out, that was a dead end."
- For the complete works of Shakespeare: cat
I will wait patiently until someone realizes that all they have to do to get around this is modulate the phase of the laser. They might even call it a phased laser, or phaser if you like abbreviations.
Isn't the fact the electron/positron pairs can be created in a vacuum by a strong enough electromagnetic field pretty interesting Physics in and of itself? What goes around comes around -- every day we get closer to resurrecting the theory of the luminiferous aether... (Yeah, I know... energy in a vacuum is not exactly the same thing.)
I've abandoned my search for truth; now I'm just looking for some useful delusions.
When you burn it, some radiation (light/IR) escapes, this is some (theoretical) energy=mass that escapes. But that are not actual quantities you take into consideration. You will run out of fluid long before this amount is weighted.
Every five or so years, someone comes forward and says that hard drives are nearing their physical limit. And then someone else makes a big breakthrough and continues the growth. Are we going to have to go through the same roller coaster ride with lasers too?
All right, consider "Create planet busting laser" to be scratched off my ToDo list. Now I've got to figure out what to do with that corner of my basement.
Suppose you were an idiot. And suppose you were a member of congress. But then I repeat myself. -- Mark Twain
Yes, we will need to move to Phasers and then Photon and Quantum torpedoes at some point.
Just because I can hook a shark from a boat, I do no offer to wrestle it in the water.
...and we'll get pod races with shit-kicking banjo music.
It is called nanoscale lasers, and it works very well.
Just tape some of those beauties together in a circle-ish shape, it will get much better results in the same space as a regular laser will, and probably with less power required due to the more efficient process of forming it.
Of course, now we just need to wait until nanotech PRETTY-MUCH-EVERYTHING gets here since the only places it really exists is in CPUs, which i wouldn't even class as nanotech since it just involves etching away most of the time.
Who knows, maybe someone will make an awesome 3D printer that works at the nanoscale ranges that can be built for less than $1000.
Replicators, here we come... in 20 years... maybe.
We need him to proclaim: "The intensity of lasers will double every two years" and everything will be fine.
right? what does one mean by "intensity"? is that simply amplitude? simply frequency? their product? if it's one or the other you can always increase the other. if it's both, then i guess you can just use a wider beam, but that means overall energy transfer rate per unit surface area is limited. well, coherent transfer, at least. anything beyond a certain threshold would diminish (exponentially) with distance. reminds me of the speed of light being constant or the "channel capacity" in information theory.
That would actually be an improvement.
You're joking, right? About how "Ken Burns will revisit that period of the galactic history and we'll get a more neutral viewpoint of the conflict."
For "more neutral viewpoint", substitute:
"Ken sank his heart and soul into this thing, and it's obvious that he's still grieving for Alderaan."
Don't forget the soft, heart-felt banjo-centric soundtrack.
-kgj
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!
"I must not fear. Fear is the mind killer." -Bene Gesserit Litany Against Fear
So we are approaching the intensity at which light turns into matter. One step (of many) to building a transporter?
On the plus side, this would explain why those laser blasters illuminate along the route rather than just at the destination.
"Don't Cross The Beams!!!!!"- Ghost Busters
That's ok, I'm just waiting for lightsabers!
*Ultra-high-energy laser fields can actually convert their light into matter as shown in the late '90s* If you can convert laser energy into matter then why not make a hamburger from the reconstituted matter stream :)http://www.youtube.com/watch?v=xHSD0tR2IOU
...what about PHASERS? What about other materials that get lased? Whenever I hear something about "we're reaching the end of [insert technology here]'s abilities" I always take it with a grain of salt. Sure, with current techniques and materials we are reaching the end of the power curve, but we're certainly not at the dead end for the technology. Or, maybe we are, but there will certainly be something that comes along to supplant it. It's not like oil where there is a finite supply of the stuff. How many times have we heard that hard drives could not possibly hold any more data?
If two or more sub-critical intensity lasers were fired at a single point at a distance, would the cascade of gamma-ray photons created in the collision be of significant destructive capacity to justify all this setup or would it just cause the lasers to disperse and fizzle out?
...before and after a nuclear reaction, I either get bored quickly or I grow senescent and die long before I get to 'after'.
They're building a 5 (five) Petawatt laser in Romania - Magurele, that's plenty enough for a deathstar.
Wouldn't passing the limit be a great way of making them?
What's scarier than physical matter moving at the speed of light? Isn't this a good thing if you were looking to create a Death Star?
It's obvious you stopped at 'Intro to Meme Physics'. Had you continued to P.H.D.[Piled Higher and Deeper] level 'Meme Physics', you would realise the synergy brought about by combining memes can be catastrophic.
For instance, should Spinal Tap attempt to jump a shark with lasers mounted on it's frikkin head while performing their new hit single: "That's No Moon!", the resulting debacle would surely go to '12' if tried in Soviet Russia, where shark jumps you!
*Disclaimer*
Don't try this at home kiddies, as an errant data point being overlooked could end the universe.
You think the 'Big Bang' was something? Ha! You ain't seen nuthin' like the sure to happen 'Big Suck' that would result as the internet[and all life as we know it] imploded!
*end Disclaimer*
No, the solution to this problem is obvious...invent bigger sharks, and mount a whole battery of frikkin' lasers on their heads. Simple, really.
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
Sure, the beam needs improbable energy but is the intensity limit actually a problem? Assuming you have the energy, wouldn't a wider beam (within the intensity limit) work as well?
Comment removed based on user account deletion
There may be a limit on intensity (watts/m2), but you simply make the beam bigger to have more total power.
Chemical energy is energy and is matter too. If you measure 8 tons of oxygen and 2 tons of hydrogen (hopefully I got my stochiometry right), and let them react, and cool off, and measure the total weright afterward you will find it changed.
Mass energy equiavelence, scroll to "Binding energy and the "mass defect".
C. Sagan : A demon haunted world:
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visit randi.org
This places a limit on the peak intensity of a laser beam, not on the peak (or average) power. It does not limit the total energy per pulse nor the power output of a laser. Furthermore, the limit is far beyond the level that turns anything the beam hits into plasma. It has no relevance to laser weapons except insofar as the the effect may someday be utilized for destructive purposes. It may have some relevance to laser fusion.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Maybe, but we would probably need to discover some new physics.
Physically, hard drives could theoretically store some amount of data based on the smallest possible magnetic domains on the platter. We have had technical limits in reducing the area that each bit uses on the hard drive platter, but I doubt that we are particularly close to hitting the physical minimum size limit.
With these lasers, the amount of energy crammed into a unit of volume is getting so high that the photons are condensing into matter when they collide with the photons of another laser beam. A single beam, twice as intense would do the same thing, but without having to collide with anything. That would pretty much be the limit of intensity. Even long before that the beam would start to become unstable, as stray ambient photons would start to cause particle cascades in the beam.
As an aside... I wonder what would happen to the laser itself when the particle cascades start to occur. Electrons and positrons are produced, so presumably the positrons would collide with the hardware of the laser and start annihilating electrons. Seems like that would tend to cause the molecular bonds within the laser to be disrupted. Maybe the free electrons would fill the gaps just as quickly, preventing damage, but even if that is the case, there would still be a lot of heat generated, which can't be good.
Put simply, in deference to you, Kent, it's like lazing a stick of dynamite.
1. 2.
So that's what they've been planning...
As I understand it this article is about using lasers to gernate electron-positron pairs from the vacuum.
A short search in google scholar showed up a lot of papers about this, for example this one from the year 2000:
http://apl.aip.org/applab/v77/i17/p2662_s1?isAuthorized=no
So what all this means is: In the beginning there was light, at high enough energy and intensity and by the electromagnetic cascade a really really big bang, (God sneezed) and what we are looking at when we peer through telescopes is the background radiation and the resultant after-effects of the great wheeze... It was big enough to send the newly created material hurtling through the universe. Force=mass*acceleration, and energy=mass*(velocity of the speed of light)*(velocity of the speed of light). One might suspect that one of two events will occur: either the process at some point becomes reversible, or we experience the heat death of the universe. If its heat death, then by what mechanism did the big bang happen in the first place? Why did it happen? How did all that material become so concentrated in the first place, since there are incredible forces acting to prevent it. Similarly, if the process isn't a one shot deal, but a cyclical (trillions of millenia long) event, how many events have happened? Can one speculate? What we know of as time bends according to the matter (light/energy/time all seem to be joined at the hip), so one might speculate: has this sort of thing (big bang) happened before our current universe? Inquiring minds want to know.
So what does this mean for the National Ignition Facility that aims to make a laser 60 times more powerful than any previous?
Ultra-high-energy laser fields can actually convert their light into matter
So I have this idea that you could blast an object into (well) nothing with intersecting laser beams, transmit data on the resulting interference patterns, then reproduce the same interference patterns at another place with intersecting laser beams powerful enough to create matter.
Sounds like teleportation to me. Anybody want to give it a go? (you furst).
http://michaelsmith.id.au
After actually reading a bit more, well... These papers are about generating positron-electron pairs from the collision of two electron beams, with the electrons being accelerated by laser.
The long-known theoretical intensity needed for pair generation is 10^28 W/cm^2. From what I just found this has not been achieved yet. In the paper linked in the summary it is stated that a single pair generated will lead to the generation of a lot more pairs: The generated electrons and positrons are accelerated by the electric field of the laser beam, reaching energies high enough to emit more pairs.
This is about the intensity in a focussed laser beam. In the laser itself you will get problems at much lower intensities.
This is just disastrous for Pink Floyd tribute bands worldwide.
Crap! Where's Gordon Freeman when you need him?
No, the solution to this problem is obvious...invent bigger sharks, and mount a whole battery of frikkin' lasers on their heads. Simple, really.
Just don't cross the beams!
This article seems to have more to do with the Ghostbusters universe as opposed to star wars ...
Nuclear accelerators, positron-electron pairs, crossing the streams,
But what do I know, I beleive anything you tell me as long as there's a steady paycheck involved
So, "sparking the vacuum" will become the new "nuking the fridge"?
The really fantastic thing about theoretical limits is .....they're theoretical and we break them all the time.
People used to think that you couldn't drive a car at more than 40mph with the wind ripping your face off.
They used to believe that the speed of sound was an actual barrier that couldn't be exceeded.
That a trip to the moon was "theoretically impossible".
Luckily, there are enough independent crazy MF's out there who say "take your theory and shove it up your ". I am building a rocket and I'm going to exceed the speed of sound or die spectacularly trying. Theorize all you want, just don't let your lack of imagination or courage stand in my way. Theories about limits should serve no other purpose than to give us an aim point...slightly beyond that limit.
Those who attempt to exceed their limits fail often, those who never try, have ALWAYS failed.
Avalanche-like electromagnetic cascade of High intensity lasers? I'll be right back, i just need to go to the hardware store and acquire a crowbar.
a few years from now when they figure out a neat trick to sidestep the problem.
Seriously, we need to stop saying 'it won't happen' and 'it can't be done' because that just means the guy talking isn't capable of doing it and someone else is going to figure it out in a few years anyway. Probably some kid who got bored and realized the 'laws' his teacher was feeding him weren't nearly as clear nore carved in stone like they are made out to be.
The won't create a super powerful laser doing it the way these guys did ... someone else using an entirely different method probably will eventually.
Their lasers won't ever be super powerful death rays like Star Wars ... someone elses might be though.
Funny thing about physics, the people who REALLY know what they are talking about also know that the more we learn, the more we realize how little we actually know. The ones who REALLY know physics don't talk in absolutes because there are no absolutes.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
The researchers at the SLAC need to recheck their results, because Andy Schlafly, Conservapedia founder and a Eagle Forum "University" instructor has noted that E=mc^2 is a liberal plot.
Yet more experimental evidence that reality has a "liberal" bias.
Luke, help me take this mask off
For future reference, the instant you make it about a 'political team' then you've pretty much show how ignorant and out of touch with the world you are, especially when it comes to politics.
If you have to use the word 'liberal' or 'conservative' to proof your point, you don't have a point to proof, just stupidity and ignorance to spew.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
Well played, rts008, well played indeed. (:
"There is a way that seems right to a man, but its end is the way of death." Proverbs 16:25 (NKJV)
For future reference, attempt to "get" the punchline.
Luke, help me take this mask off
I thought it was conservatives who are ignorant and out of touch with the world. They astound me every day with how much so!
What a fool believes, he sees, no wise man has the power to reason away.
The page wouldn't load. Probably because of Murdoch's or Fox's dastardly meddling in the internets!
Aw come on, everybody knows that Hiroshima and Nagasaki were just figments of the liberal media.
thegodmovie.com - watch it
Why is it, that on a forum filled with nerds, I am the only one who thinks about how this could be used to simultaneously create lots of specific impulse in atmospheric conditions, as well as a sustained (but admittedly much lower) specific impulse in spaceflight conditions, without expelling a reactant?
It's so simple! You use a very high quality parabolic concentrator, and enough laser emitters to create these conditions at the collimation point. In atmospheric conditions, the "Bloom" produced at this point would heat the atmospheric gas to insane temperatures, providing thrust against the reflector. (quite a bit of thrust in fact. There is already a functional prototype of such a design.)
In non-atmospheric conditions, you could activate a secondary magnetic "bottle" using coil windings under/behind the reflector, to constrain the generated electron/positron plasma, and forcibly expel it to gain thrust. (electrons and positrons have a very small mass.) This way you would have decoupled thrust generated in a vacuum. (Mass-less photons are emitted toward the aft section of the ship from the emitter array. These photons collimate in the concentrator. Electron/positron pairs are formed from the EM energy. This mass energy is then expelled/pushed against using a magnetic field to create thrust.
It would be a continuous thruster, which albeit weaker than an ion propulsion system, would not require a reactant like ion does, while having the same basic advantage: the "Burn" could be continuous, and sustained.
Even more interesting would be if you could take advantage of the cascade effect; you WANT there to be matter created at the collimation point. The more antiparticle pairs created, the more thrust generated against the constricting magnetic field before being re-emitted as gamma rays. (interestingly, the constriction field might allow the plasma itself to function as a pumped laser medium, with an innate frequency of the gamma-ray wavelength.)
Admittedly-- the downside is that the gamma-ray radiation produced would be... well... not so good for the crew. :D Better have LOTS of shielding between the engine pod and the crewed portions of the ship!
Made me laugh!
-kgj
Talk about being astounded.