Physicists Say They've Built an Atom Laser That Can Run 'Forever' (sciencealert.com) 46
A new breakthrough has allowed physicists to create a beam of atoms that behaves the same way as a laser, and that can theoretically stay on "forever." ScienceAlert reports: At the root of the atom laser is a state of matter called a Bose-Einstein condensate, or BEC. A BEC is created by cooling a cloud of bosons to just a fraction above absolute zero. At such low temperatures, the atoms sink to their lowest possible energy state without stopping completely. When they reach these low energies, the particles' quantum properties can no longer interfere with each other; they move close enough to each other to sort of overlap, resulting in a high-density cloud of atoms that behaves like one 'super atom' or matter wave. However, BECs are something of a paradox. They're very fragile; even light can destroy a BEC. Given that the atoms in a BEC are cooled using optical lasers, this usually means that a BEC's existence is fleeting.
Atom lasers that scientists have managed to achieve to date have been of the pulsed, rather than continuous variety; and involve firing off just one pulse before a new BEC needs to be generated. In order to create a continuous BEC, a team of researchers at the University of Amsterdam in the Netherlands realized something needed to change. "In previous experiments, the gradual cooling of atoms was all done in one place. In our setup, we decided to spread the cooling steps not over time, but in space: we make the atoms move while they progress through consecutive cooling steps," explained physicist Florian Schreck. "In the end, ultracold atoms arrive at the heart of the experiment, where they can be used to form coherent matter waves in a BEC. But while these atoms are being used, new atoms are already on their way to replenish the BEC. In this way, we can keep the process going -- essentially forever." The research has been published in the journal Nature.
Atom lasers that scientists have managed to achieve to date have been of the pulsed, rather than continuous variety; and involve firing off just one pulse before a new BEC needs to be generated. In order to create a continuous BEC, a team of researchers at the University of Amsterdam in the Netherlands realized something needed to change. "In previous experiments, the gradual cooling of atoms was all done in one place. In our setup, we decided to spread the cooling steps not over time, but in space: we make the atoms move while they progress through consecutive cooling steps," explained physicist Florian Schreck. "In the end, ultracold atoms arrive at the heart of the experiment, where they can be used to form coherent matter waves in a BEC. But while these atoms are being used, new atoms are already on their way to replenish the BEC. In this way, we can keep the process going -- essentially forever." The research has been published in the journal Nature.
Wait a second (Score:2, Redundant)
. "In the end, ultracold atoms arrive at the heart of the experiment, where they can be used to form coherent matter waves in a BEC. But while these atoms are being used, new atoms are already on their way to replenish the BEC. In this way, we can keep the process going -- essentially forever."
It can run forever as long as you keep replacing it? Isn't that true of a lightbulb?
Re: Wait a second (Score:4, Informative)
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Misleading title (Score:5, Insightful)
Sort of implies perpetual motion. Actually just runs as long as it is powered up and on. Should be something like 'continuous coherent atom stream created', which should be impressive enough.
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Perpetual motion exist in the universe. It's just not generally possible to extract useful energy from it.
For example, the movement of objects in stable orbits under the influence of gravity is definitely motion, and also definitely perpetual.
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Would not tidal forces in the bodies also be generating heat so will also take energy from the system. (assuming they are not rotation locked). And of course they would not be the only objects in the universe, so the question of if its really a stable orbit is not so simple.
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Yeah, well, it would be perpetual if it wasn't for reality.
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Definitely not perpetual. Long lasting compared to human lifetimes but not forever.
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It is perpetual in the sense that it does not lose any energy over time.
It is not, however, a perpetual motion *machine* because a machine, by definition, does work. Bodies simply following the curvature of space time do not do any work.
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An object in motion stays in motion unless acted upon by a force.
The first law of motion, basically says there is Perpetual motion.
However even stable orbits are not that stable, as they apply forces to other object (like the tides) which can distort the orbit over time, where the object will either fly away from the orbit, or crash into the larger object.
But collecting energy from say Tide forces is not power for forever, at some point the Moon will finally leave orbit, and the tides will stop. However in
Re: Misleading title (Score:1)
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Isn't that true of a lightbulb?
You can't keep a lamp running while you replace the light bulb. Which is sort of how the current generation of BEC lasers work. This sounds like it can be replenished continuously while it is still lit. Sort of like a whale oil lamp.
We've just taken a giant step backwards in technology.
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I think ti means it can operate continuously instead of only for a brief pulse, sort of like how the first lasers could only produce a brief pulse, and then later they got them to work continuously.
A described by the article, the main problem previously was that the cooling laser used to cool the atoms in the Bose-Einstein Condensate would then cause it to collapse.
Now they do that cooling elsewhere and shield the BEC from the cooling laser light so it doesn't collapse, allowing it to operate continuously.
AASER you idiots (Score:1)
Not MASER (the original)
Not LASER (current fad)
AASER (the future)
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What about ASSER ? Atoms Suppressed by Simulated Emission of Radiation.
Fusion? (Score:2)
Long-lived Bose-Einstein condensate particle beams? I wonder if they can be used to achieve practical amounts of fusion?
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Even if you could, would the amount of energy needed to cool the atoms going into the BEC be low enough that you can actually get useful amounts of energy out of the whole thing?
Re: Fusion? (Score:1)
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That's the ultimate question, isn't it? What is this actually good for?
That was pretty much the reaction to the LASER as well. We found a couple of uses for those in the following 80 years.
Charles Townes (Score:4, Interesting)
That was pretty much the reaction to the LASER as well. We found a couple of uses for those in the following 80 years.
When I was doing my doctorate, I had the good fortune to meet Charles Townes. According to him, he was told the maser was a fantastic piece of physics, but that it would never have any use.
Re:Fusion? (Score:4, Informative)
What is this actually good for? Scientific Knowledge. Maybe you have heard of it, it was once considered a good thing.
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IIUC, this is more engineering knowledge than scientific knowledge. Still a good thing, but in a different category. And one that makes "what can you use it for" more relevant, even if you can't answer it at the moment.
Re: Fusion? (Score:1)
Very loose definition of "forever" (Score:4, Funny)
I'm picturing the stars going out one by one, until the universe is completely black. But there, out of nowhere, appears, an atom laser, still bravely shining in the darkness. And then there was a HUGE explosion. Wait, I think we just solved how the Big Bang happened!
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Even the linked article headline puts the "forever" in quotes.
"Forever" (Score:2, Interesting)
What they actually mean is just a steady matter wave. First thing that comes to mind is atom wave microscopy.
Is this effective a ... (Score:1)
... particle beam?
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More specifically, if what they say is true it's a continuous wave beam of coherent particles, with the continuous wave being the novel part.
Similarly (Score:1)
I found I can keep a tin can moving forever along the road - all I have to do is just keep kicking it.
but what will the script writers do without (Score:2)
Cows are spherical. (Score:2)
What is the wavelength? (Score:2)
Fascinating.
I was struggling to imagine what an atom laser beam, either shooting straight out or interfering like in a double slit experiment, would look like. Would it be visible to incident light?
Anyone know what the (deBroglie I guess?) wavelength of an atom is?
Seems it could be used for atom holography and interferometers among other things. How cool (pun not intended)
https://en.wikipedia.org/wiki/... [wikipedia.org]
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It varies with the mass of the particle. IIRC even a baseball has a de Broglie wavelength. Not a very useful one, though.
OTOH, I'm not sure how one would define the de Broglie wavelength of a mass of atoms in a Bose-Einstein condensate where you were continually extracting atoms from one end while adding them at the other.
but... (Score:2)
The Possibilities! (Score:2)
The possibilities are limitless!
no wait, that's not right.
The possibilities are limited!
Very bad title. Laser is not running for ever. (Score:2)
What they have done was to set up a stream of ultra cold atoms to be fed into the BEC as the atoms already in that state "evaporate". Thus BEC can last for ever.
Like I water my tomato and pepper plant beds with a drip irrigation system to keep them hydrated "forever".
Imagine a beowful cluster of (Score:2)
These.