The second law of thermodynamics states that the entropy -- sometimes thought of as disorder -- of a system cannot decrease over time. One of the consequences of this law is that it precludes the possibility of a perpetual motion device. Around 1870, James Clerk Maxwell proposed a thought experiment in which a demon could open and close a gate between two chambers of gas, allowing warmer atoms to pass in one direction and cooler atoms to pass in the other. This sorting, which required no energy input, would result in a reduction of entropy in the system and a temperature difference between the two chambers that could be used as a heat pump to perform work, thus violating the second law.
"Later work has shown that the demon doesn't actually violate the second law and subsequently there have been many attempts to devise experimental systems that behave like the demon," said [physics professor David] Weiss. "There have been some successes at very small scales, but we've created a system in which we can manipulate a large number of atoms, organizing them in a way that reduces the system's entropy, just like the demon."
The researchers use lasers to trap and cool atoms in a three-dimensional lattice with 125 positions arranged as a 5 by 5 by 5 cube. They then randomly fill about half of the positions in the lattice with atoms. By adjusting the polarization of the laser traps, the researchers can move atoms individually or in groups, reorganizing the randomly distributed atoms to fully fill either 5 by 5 by 2 or 4 by 4 by 3 subsets of the lattice.
"Because the atoms are cooled to almost as low a temperature as possible, the entropy of the system is almost entirely defined by the random configuration of the atoms within the lattice," said Weiss. "In systems where the atoms are not super-cooled, the vibration of the atoms makes up the majority of the system's entropy. In such a system, organizing the atoms does little to change the entropy, but in our experiment, we show that organizing the atoms lowers the entropy within the system by a factor of about 2.4."
(Score: 2, Informative) by Anonymous Coward on Monday September 10 2018, @07:34PM (2 children)
So they introduced an outside force - the lasers - into this "system" to cool the atoms. Where did the heat from the atoms go?
(Score: -1, Spam) by Anonymous Coward on Monday September 10 2018, @07:36PM
Springs. The sound of springs could be heard from within the room. From the sound, most people would guess that someone was bouncing around on a bed. And they would be correct. Within the room, and on top of the small bed, was... a blob.
It could only be described as a blob. No, if one looked closely, they would see that it was actually a man. It was a man whose head contained no hair except on the sides; a man whose face was filled with craters and fat rolls; a man whose eyes were so small that they could only be described as beads; and a man whose level of energy belied his appearance. This man's name was Howwy.
Howwy bounced on the bed with glee. In fact, despite the man's otherwise hideous appearance, one could say that this bouncing man was truly adorable. The man was alone, and yet he was having so much fun. Wait, alone? No, there was something else there.
Howwy lifted his head up, and a string of saliva connected his mouth to something else's. The thing's eyes were dead; it was to the point where most people would reach the conclusion that it itself was dead. However, this was not the case. You see, the little girl had simply given up all hope; her screams, cries, and begs for mercy did not cause the man to stop, after all, so what was the point? Thus, the naked little girl simply laid motionlessly on the bed and let the man do as he pleased. And that was precisely what Howwy did, until he noticed that the girl was no longer reacting to being violated. The man clicked his tongue and grabbed the girl's head with his fat, grubby hands. Then-
Snap!!! A lump of meat was tossed to the side like the garbage it was; it landed on the same pile as all the other trash, which was to the left of the bed. Howwy snorted, and then grabbed a bound child that was located to the right of the bed. Then, the bouncing began once again. And, thankfully, so did the screaming and crying.
Howwy 'feasted' upon the child. It was like a well-oiled machine; women and children went in, and brutalized corpses - as well as feces and urine from the terrified children - went out. Clearly, the product being produced by this machine was pleasure for Howwy. Suddenly, he realized that there was nothing left. Nothing at all.
Howwy grunted in disapproval. That woman and her five children hadn't even been able to serve as his breakfast. The gluttonous man hungered yet still. So, he screeched, "Next!" But, no one came.
"Next!! Next!!!" Howwy screeched. But, again, no one came. No women or children came into the room to be utilized by the man. Intolerable. Absolutely intolerable! How dare they make this great man seek them out himself! Howwy's expression went from one of confusion to one of pure, seething wrath; his anger was such that it was as if atomic bombs were detonating inside his skull. He would have his vengeance. Howwy slowly jiggled off the bed, and then began walking away. The man waddled towards the next house, which, to his knowledge, contained a few children and their mommy.
He swore. The man swore that would enact supreme vengeance upon those wretched sows for violating his fundamental rights as a man. This was the true extent of a hero's resolve.
(Score: 1) by shrewdsheep on Tuesday September 11 2018, @08:04AM
That is the initial setup and doesn't count. The problem is the re-arrangement of the atoms. Energy expended for that is apparently not counted otherwise the entropy could not decrease.
(Score: 2, Funny) by Anonymous Coward on Monday September 10 2018, @07:40PM (3 children)
A Princess, and Elf, and Maxwell's Demon walk into a bar
(Score: 5, Funny) by maxwell demon on Monday September 10 2018, @08:22PM (2 children)
That will never happen. The princess will not enter the bar because of all those ordinary people. The elf will not enter because of all those humans. And I'll not enter because of all that entropy! :-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 4, Funny) by JoeMerchant on Monday September 10 2018, @10:10PM (1 child)
Would keep you busy, though, opening and closing the bar door.
🌻🌻🌻🌻 [google.com]
(Score: 2) by bob_super on Monday September 10 2018, @10:58PM
If my neighbor is at the bar, there will definitely be more chaos with the door closed.
(Score: 1) by curril on Monday September 10 2018, @09:18PM
Essentially it looks like the researchers did something pretty cool--created 5x5x5 cube that they could move atoms around in. Then they measured the entropy of the cube after they organized the atoms and found, unsurprisingly, that the entropy was lower. Fascinating stuff. But then they had to throw in that it could be used as a quantum computer as grant bait. And they didn't really follow through on how it relates to Maxwell's demon. I guess it proves in this highly specific context that organizing atoms reduces entropy, but it doesn't really prove that the hypothetical demon that organizes atoms can't exist.
(Score: 2, Funny) by Anonymous Coward on Monday September 10 2018, @09:49PM (1 child)
Entropy, how can I explain it? I'll take it frame by frame it
To have you all jump and shout and saying it
Let's just say that it's a measure of disorder
In a system that is closed, like with a border
[...]
[Chorus]
You down with entropy? (Yeah, you know me!) (x3)
Who's down with entropy? (Every last homey!)
[...]
Researchers always try to use the second law
To create perpetual motion machines, but their theory has a flaw
The second law is quite precise about where it applies
Only in a closed system must the entropy count rise
This experiment is not a closed system, it's powered by their lasers
So fuck the damn researchers, Doomsday get my gun
(With apologies to MC Hawking and Stephen Hawking, RIP)
(Score: 3, Informative) by Thexalon on Tuesday September 11 2018, @12:20AM
At least link the original track: MC Hawking - Entropy [youtube.com]
"Think of how stupid the average person is. Then realize half of 'em are stupider than that." - George Carlin
(Score: 2, Funny) by Anonymous Coward on Monday September 10 2018, @10:32PM (3 children)
Please, test it in the White House, we are desperate!
(Score: 2, Touché) by bob_super on Monday September 10 2018, @11:02PM (2 children)
We are one bullet, or one KFC leg, away from the reduced entropy of President Pence.
Would you really like to find yourself in that state ? (Abort, Retry, Fail)
(Score: 1, Insightful) by Anonymous Coward on Tuesday September 11 2018, @01:12AM
VP may be a zealot, but he's a sane zealot. (At least as close as a zealot can come to being sane.)
(Score: 4, Interesting) by vux984 on Tuesday September 11 2018, @06:25AM
Yes. At least he'd give us some peace and quiet and the rest of the world would be able to rely on the US, and the rest of the government would be able to rely on the white house. Most of the the real policy work going on in government wouldn't change - same deregulation push, same immigration nonsense, same supreme court picks, same bullshit, but the signal to noise ratio would get a lot better. Hell, at this point, I think Palin would have been a better president.
(Score: 0) by Anonymous Coward on Tuesday September 11 2018, @02:57AM
Once they measured the atom positions, these were known and no longer random. Then there was only one possible configuration. Entropy is the logarithm of this number, i.e. 0. It didn't change when they moved the atoms.
(Score: 2) by PiMuNu on Tuesday September 11 2018, @10:12AM
https://en.wikipedia.org/wiki/Stochastic_cooling [wikipedia.org]
(Score: 2) by RandomFactor on Saturday September 15 2018, @05:43PM
I recall reading something that explained that the demon didn't actually break the second law once. Something about the demon causing a corresponding increase in entropy by measuring the molecules and manipulating the gate I think.
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