Re: Quantum Physics

by halfwise Tue May 17, 2016 9:13 pm

If true, this turns all of quantum mechanics on it's head. I'm inclined to not believe it's true not just because it's so shocking, but because they chose to publish in the little know "scientific advances" instead of Science or Nature. They may have tried and been rejected.

As for why this would turn quantum mechanics on it's head, there's something called fermion and boson statistics. Integer spins are boson and half integer are fermion. They behave very differently for reasons which even Richard Feynman had a hard time explaining and even most physicists (including me) do not really understand. But photons CAN'T be Fermions. They just can't.

http://www.upi.com/Science_News/2016/05/17/Scientists-discover-new-form-of-light/9061463490086/

Scientists discover new form of light
"Our discovery will have real impacts for the study of light waves in areas such as secure optical communications," physicist John Donegan said.
By Brooks Hays | May 17, 2016 at 10:36 AM

Researchers recently discovered a beam of light with photons traveling with an angular momentum never before measured.

DUBLIN, Ireland, May 17 (UPI) -- Researchers in Ireland have discovered a new form of light. Their discovery is expected to reshape scientists' understanding of light's basic nature.

Angular momentum describes the rotation of a light beam around its axis. Until now, researchers believed the angular momentum was always a multiple of Planck's constant -- a constant ratio that describes the relationship between photon energy and frequency, and also sets the scale for quantum mechanics.

The newly discovered form of light, however, features photons with an angular momentum of just half the value of Planck's constant. The difference sounds small, but researchers say the significance of the discovery is great.

"For a beam of light, although traveling in a straight line it can also be rotating around its own axis," John Donegan, a professor at Trinity College Dublin's School of Physics, explained in a news release. "So when light from the mirror hits your eye in the morning, every photon twists your eye a little, one way or another."

"Our discovery will have real impacts for the study of light waves in areas such as secure optical communications," Donegan added.

Researchers made their discovery after passing light through special crystals to create a light beam with a hollow, screw-like structure. Using quantum mechanics, the physicists theorized that the beam's twisting photons were being slowed to a half-integer of Planck's constant.

The team of researchers then designed a device to measure the beam's angular momentum as it passed through the crystal. As they had predicted, they registered a shift in the flow of photons caused by quantum effects.

The researchers described their discovery in a paper published this week in the journal Science Advances.

"What I think is so exciting about this result is that even this fundamental property of light, that physicists have always thought was fixed, can be changed," concluded Paul Eastham, assistant professor of physics at Trinity.

by David H Tue May 17, 2016 9:57 pm

Wow!

Quantum Physics - Page 31 Pxpr_f-maxage-0

by Eldorion Tue May 17, 2016 10:13 pm

I'd definitely want to wait to see if the study can be replicated before getting excited, but if it is this certianly sounds like a holy shit moment.

by halfwise Tue May 17, 2016 11:02 pm

I looked up the paper. As usual the reporting glossed over the details. The fractional angular momentum is the photon's intrinsic spin plus the orbital angular momentum. How the hell you get photons to do electron type orbits is beyond me: photons have no charge. But magnetic fields and shit are involved. I'll have to go back and work out the orbital stuff, but no....the light they are measuring isn't any different. The orbital structures are, which is pretty interesting in itself. But I have to figure out how you get a photon to 'orbit'.

by David H Wed May 18, 2016 12:08 am

You're way beyond me now, but I'm on the edge of my seat! Please keep us posted! bounce

by halfwise Wed May 18, 2016 12:41 am

I'm reading but it's all kind of swirling around in my head. It goes deep into the rather magical theory of quantum angular momentum, and I'd have to go and review that. May not happen anytime soon, and certainly would not be easily explained to a lay audience. The quantization of angular momentum can certainly be conveyed (the basis of the Bohr atom), but integer versus half-integer is a purely mathematical thing. And while particles are fixed as one or the other, orbits can switch under certain circumstances. Something called the fractional quantum Hall effect demonstrated this for electrons decades ago. Something to look up as relevant.

As to how to get a photon to 'orbit' - refraction is a partial orbit: light bends as it goes from air to water for instance. Even setting up a series of mirrors bouncing light around in a circle would count.

by Mrs Figg Wed May 18, 2016 11:22 pm

a new form of light! Shocked

mind boggled.

by Mrs Figg Wed May 18, 2016 11:26 pm

its got nothing to do with finding a new colour is it? just thinking out loud.

by halfwise Wed May 18, 2016 11:31 pm

It's NOT NOT NOT NOT!.... a new form of light. Ignore the headlines written by COMPLETE ignoramuses.

Light is just being made to bounce around in a way people weren't sure it could do.

Think of it as a new dance move for light. The dancer doesn't change. Neither has the light.

by Mrs Figg Wed May 18, 2016 11:32 pm

has its speed changed?

by halfwise Wed May 18, 2016 11:47 pm

Nope.

It's angular momentum. Best comparison is to the hydrogen atom. When folks first found about about electrons and protons, and that one of each was in the hydrogen atom, they imagined the electron circling the proton like the earth circles the sun. But the earth could be in any of a continuous set of orbits: increase the radius by an inch, decrease it by 4 miles; the earth could do any of that - nothing stopping it.

But since the electron is charged it must produce electromagnetic waves as it orbits (the earth must also produce gravity waves, but gravity is so weak in comparison we don't notice it.) The waves should correspond to all different possible orbits if you have a gazillion hydrogen atoms.

But you don't see a gazillion different wavelengths, you see a very specific set, and that's all you get. It was very strange and unnerving. Eventually Bohr came along and said the angular momentum had to be quantized: the most common wave corresponded to one unit of angular momentum, another wavelength corresponded to 2 units of angular momentum, etc....and nothing in between.

Now it turns out particles don't just orbit, they can also spin around their own axes (rotation), and this is also quantized, but for strange reasons which most physicists (including me) don't understand well enough to explain, the rotational angular momentum comes in units that are offset by half from the orbital angular momentum: 1.5, 2.5, 3.5 etc compared to 1,2,3...

Even parts of an orbit count: if you get something to change direction, it's part of an orbit and must be quantized. So if you get light to bend around it should do this dance in integral quanta.

It's been found that electrons can be made to do half integral bending, and I don't remember the details, but the rules governing orbital angular momentum seem to be less strict than that governing rotational angular momentum. So if it can be done with electrons, it could probably be done with light. It's just that nobody figured out how to do it until now.

by Mrs Figg Thu May 19, 2016 6:44 pm

((((((I will just nod and try and look clever )))))

by Pettytyrant101 Thu May 19, 2016 6:56 pm

{{{Your not alone Figg Mad

}}}

by halfwise Thu May 19, 2016 7:26 pm

I shouldn't really have expected anyone to follow that. Shrugging

And if I tried to go into more detail so that maybe people could follow, it would either take immense concentration on everyone's parts, bore them half to death, and at the end they'd likely go 'so what?', which in the end was more or less my final reaction once I knew what was going on.

I was misled by flambuoyant titles and should have read the damn paper before I posted anything. Dratted reporters. Extremely Crabbit

by chris63 Sun May 22, 2016 3:03 am

by halfwise Sun May 22, 2016 3:45 am

Like hauling yourself by your bootstraps.

by chris63 Sun May 22, 2016 9:47 am

Do you think that would work ?

by azriel Sun May 22, 2016 9:51 am

I got it

by Mrs Figg Sun May 22, 2016 6:23 pm

you know they keep announcing they have found planets that look like Earth. I am still waiting for the planet that looks just like Uranus.

silent

by malickfan Sun May 22, 2016 6:55 pm

Mrs Figg wrote:you know they keep announcing they have found planets that look like Earth. I am still waiting for the planet that looks just like Uranus.

by David H Sun May 22, 2016 10:24 pm

by Mrs Figg Sun May 22, 2016 11:11 pm

by chris63 Mon May 23, 2016 6:16 am

Nice one Dave, nearly spat out my coffee.

Quantum Physics - Page 31 Tumblr_nk6lp22lJU1re3x32o1_500

by chris63 Sat Jun 04, 2016 4:45 am

by azriel Sat Jun 04, 2016 8:36 am

Oooo-er, thats thought provoking