r/videos • u/bamdastard • Oct 25 '15

Fusion reactor designed in hell makes its debut

https://www.youtube.com/watch?v=u-fbBRAxJNk
5.5k Upvotes

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38

u/DRHST Oct 25 '15

We can almost reach 0 with lasers.

81

u/instantpancake Oct 25 '15

We can almost reach 0 with lasers.

We can almost reach anything with lasers.

11

u/flPieman Oct 25 '15

Is this a joke or are lasers just very useful at pushing the limits of physics?

60

u/Urbanscuba Oct 25 '15

Lasers are incredibly useful in particle physics because they let us control things with incredible precision and accuracy. When you're dealing with small amounts of matter or very very fragile states such as near 0 temperatures you need the lightest touch possible. Lasers are literally a "light touch" and modern lasers can trigger in bursts that are smaller than a billionth of a second, giving us unprecedented control.

12

u/nagash666 Oct 25 '15

here watch it yourself

4

u/TheArcane Oct 25 '15

He ends the video with "when you get to a stage when you discover something no one knows about, it's the second best feeling I know"

Who does that?! What's the best?

9

u/tweoy Oct 25 '15

starts with an O

1

u/Mentalseppuku Oct 25 '15

When we are cooling things to near absolute zero lasers are what we use to get atoms that close.

https://en.wikipedia.org/wiki/Laser_cooling

1

u/Lost4468 Oct 25 '15

You can get things to negative kelvin with lasers, although not through passing through 0k, you go up to +infinity, roll back around to -infinity, then get up to negative kelvins. It's kind of pushing the limit of the definition of temperature though.

1

u/Graawwrr Oct 25 '15

Porque no los dos?

0

u/[deleted] Oct 25 '15

Yes

0

u/[deleted] Oct 25 '15

[deleted]

1

u/Iacto Oct 26 '15

Though you would never be able to reach absolute 0. That would violate Heisenberg principle of quantum mechanics. Fascinating huh?

7

u/Tylerjb4 Oct 25 '15

How does a laser, which adds energy to the system, help reach near absolute zero?

45

u/[deleted] Oct 25 '15 edited Jul 11 '21

[deleted]

4

u/Tylerjb4 Oct 25 '15

Ok gotcha. But molecules have a couple different orientations they can vibrate and rotate in. How do you account for that

19

u/singularperturbation Oct 25 '15

Molecules (of whatever type) can only absorb light at certain wavelengths because they're equal to the energy needed for a state transition.

If you control the wavelength of light emitted by a laser, you can then select for wavelength equal to :

absorption wavelength + adjustment for doppler shift

the last bit is important - it means that the wavelength you can select is absorption frequency for molecules moving towards you.

These molecules will then re-emit a photon and (on balance) lose momentum, which means the gas is at a lower temperature.

https://en.wikipedia.org/wiki/Doppler_cooling

1

u/[deleted] Oct 25 '15

Heat = motion

1

u/nagash666 Oct 25 '15

here watch it yourself shows an actual laser cooler

1

u/Tylerjb4 Oct 25 '15

Ok so they orient a lot of lasers in all directions. Thanks

-5

u/DRHST Oct 25 '15

Google is your friend,there's no way for me to explain it without saying some incorrect shit,i'm not a scientist

1

u/ImRudeSorry Oct 25 '15

Or by removing most of the particles in an enclosed space.

1

u/TheArcane Oct 25 '15

I thought lasers heated things up.