

Surprising magnetic effect of light discovered at University of Michigan (2011) - Splendor
http://michigantoday.umich.edu/2011/04/story.php?id=7980

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selimthegrim
They goofed, see the comments on their paper
([http://prl.aps.org/abstract/PRL/v98/i9/e093901](http://prl.aps.org/abstract/PRL/v98/i9/e093901)).

namely

[http://scholar.google.com/scholar?cluster=169089650815815794...](http://scholar.google.com/scholar?cluster=16908965081581579446&hl=en&as_sdt=0,38)

and

[http://scholar.google.com/scholar?cluster=274756171832259655...](http://scholar.google.com/scholar?cluster=2747561718322596551&hl=en&as_sdt=0,38)

~~~
prawks
Prime example of why storing papers behind paywalls is a bad idea.

I can't read anything linked.

 _The authors then invoke Faraday 's law H r E= i! 0 and conclude that the
integral on the left side of Eq.(2) is identical to the first integral on the
right. The theoretical result claimed in the Letter is directly predicated on
this conclusion. This conclusion, however, is valid only ..._

Continued?

 _where m (p) is the peak value of induced magnetic (electric) dipole moment
and r ( " r) is the ratio of magnetic (electric) permeability (permittivity)
of the sphere and the surrounding medium at the given frequency. Equation (9)
in [1] is a consequence of Eq.(8): JM º¿ 1= ..._

~~~
pavel_lishin
This rendered very oddly in Chrome on OS X:
[http://i.imgur.com/xFiNhav.png](http://i.imgur.com/xFiNhav.png)

~~~
gus_massa
PDF of first comment:
[http://muri.lci.kent.edu/Publications/Papers_KSU/PPM_PRL99_2...](http://muri.lci.kent.edu/Publications/Papers_KSU/PPM_PRL99_2007.pdf)

The strange symbols appear because LaTeX use strange fonts with strange
encodings, so the formulas look nice in the pdf but if you cut and paste them,
and use a standard font to render the symbols then they are mapped to random
characters in the standard fonts.

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thornad
Hardly surprising. Explanation here:
[http://www.youtube.com/watch?v=lpI6ikj1G-s](http://www.youtube.com/watch?v=lpI6ikj1G-s)

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methehack
Does anyone know what happened with this? I googled "magnetic effects of light
new type of solar cell" but I only got press from 2011 in the results.

~~~
jpdoctor
The title of the paper is: Optically-induced charge separation and terahertz
emission in unbiased dielectrics.

The news release is completely out-to-lunch (eg _" Light has electric and
magnetic components. Until now, scientists thought the effects of the magnetic
field were so weak that they could be ignored._" Are you kidding? Light
doesn't even propagate without the magnetic field) so I'd start by tracking
citations of the original paper.

~~~
ctdonath
We know it's electro _magnetic_ waves, but as it says we tend to ignore the
latter part.

Having just studied for (and passed! yay me!) my amateur radio license exam,
I've been mulling over this common omission of consideration of propagating
magnetics. Phase too: we're so focused on frequency that we overlook phase.
Polarization is also underrated, with a study last year suggesting "infinite
bandwidth" (so said news reports) when used creatively.

Revisiting basics can reveal wonderous things.

~~~
simcop2387
If you take a look at how QAM works mathematically, it's getting such
wonderful results because it's using two carriers with phase differences to do
everything. It lets you do some really cool things depending on how well you
can recover that phase.

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kibwen
Note that this from 2011. But it's still pretty cool when discoveries occur
that weren't predicted by the models.

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ynniv
It must feel good to discover something 8 orders of magnitude stronger than
predicted.

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gboudrias
I emailed the author of the paper. Hope he gets back to us, this is cool.

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mdturnerphys
"The light . . . must be focused to an intensity of 10 million watts per
square centimeter. Sunlight isn't this intense on its own . . ."

Just a bit of an understatement.

~~~
ctdonath
Start with full-on solar intensity of 1000 watts per square meter. 100x100
meters gives the power input needed. Focus that on 1m^2, then focus that in
turn to 1cm^2. Sounds doable.

~~~
bcbrown
It's not that simple. There's a minimum beam size, and passive optics won't
let you alter that.

[https://en.wikipedia.org/wiki/Gaussian_beam#Beam_width_or_sp...](https://en.wikipedia.org/wiki/Gaussian_beam#Beam_width_or_spot_size)

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dlhavema
so were problems found with the tech so it was abandoned or what? hard to know
where it's going if anywhere with no followup...

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akiselev
Welcome to academia.

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gailees
How does Michigan consistently have such crazy research going on?

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mikeyouse
It's typically in the top 3 public US colleges and top 20 overall. The average
SAT score coming in is 1900 with over 25% of their freshman class arriving
with 4.0 GPAs out of high school. So they have a pretty good program by
typical measures.

Their advantage then over similar schools is the sheer size and funding. A
school like Dartmouth probably has 'smarter' students enrolling on average,
but Michigan's engineering college has more students (8,000+) than the
entirety of Dartmouth (6,100). So take those 8,000 engineering students and
add another 32,000 in the non-engineering tracks (many of whom are in
sciences, medicine, mathematics, physics, etc.) and you're bound to produce
some interesting research.

So a ton of smart students, but then there's the money... U of M has the 8th
largest endowment ($8 billion) in the US and the 2nd largest research budget
at over $1.2 billion per year. They spent $190mm on engineering research last
year and over $550mm in the medical school on health / biotech R&D.

One could ask why they don't produce more than they do.

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Locke1689
Realistically, the only things that matter that you mentioned are money (not
the endowment, though, just the research budget, AKA grant money) and the
facilities.

Undergrads are basically worthless (in fact, they may be a detriment because
they drain resources from the professors and the grad students).

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brisance
Does this mean tractor beams can be made real? :)

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akiselev
They can already be made real.

A) Make sure your ship is bigger

B) Shoot a ton of highly charged electron beams at the enemy space ship to
ionize their hull

C) Magnetize your hull to the opposite charge and bring in the ship

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tekromancr
How does one go about decelerating the other ship before it smashes into
yours?

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OnTheRocks
D) Magnetize your hull to the same charge and bring in the ship

~~~
tekromancr
The other ship would have momentum in the direction Of you. I suppose you
could swap your hulls charge to repell

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mikeleung
this is 2 years old

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Zircom
Thank you for helping those of us unable to do basic arithmetic.

