
Free electron laser – A fourth-generation synchrotron light source [video] - sasvari
https://media.ccc.de/v/34c3-8832-free_electron_lasers
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awful
This machine is the stringing together major physics, optical, and electronic
discoveries of the past century or so into a precision machine with incredible
new capabilities. From the electron sources, the RF technologies, vacuum and
supercon technology, the Bremstrellung (sp?), to the photon grouping, to the
obviously advanced detectors with enormous parallel data throughput. One of
the best talks I have seen. Bravo.

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ginko
>Bremstrellung (sp?)

[https://en.wikipedia.org/wiki/Bremsstrahlung](https://en.wikipedia.org/wiki/Bremsstrahlung)

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mrybczyn
CCC.DE is slow for me, here's a youtube link to same video. Worth watching!

[https://www.youtube.com/watch?v=RKqof77pKBc](https://www.youtube.com/watch?v=RKqof77pKBc)

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moritzsimon
I saw the talk live and the nerdism, physicians humor and the transfered
knowledge was really mind blowing. It's an awesome insight into the foundation
and building of a really large human made machine. Watch!

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TrueTom
It would've been even better without the unnecessary political commentary.

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ginko
I was at the talk. What political commentary are you even talking about?

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simplyfantast
Not sure how the parent would respond, but early on, while discussing Rosalind
Franklin's DNA diffraction findings, he makes an unnecessary comment about the
Nobel prize going to "the two white men." It seemed out of place compared to
the rest of his talk.

I didn't feel like the talk gave off an overtly political tone.

The New England Journal of Medicine on the other hand...cancelled my
subscription due to how political it has become. Still has very good review
articles, though.

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frostburg
Silence is political too, you just don't notice because you agree with it.

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ralfd
The dig at the beginning that „white men“ got 1962 the Nobel prize for DNA
instead Rosalind Franklin was cringey and factually incorrect. Frankin died in
1958 and the Nobel prize is not awarded posthumously. Had she lived she would
have gotten it too, there is no question about that.

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AbrahamParangi
While the Nobel prize is indeed not awarded posthumously, the characterization
of Rosalind Franklin being unfairly dispossessed of credit is very reasonable.

Watson and Crick achieved great fame for "Discovering the double helix
structure of DNA". Their original paper:

1) contained no experimental data

2) does not cite Franklin

3) was based on her as-yet unpublished X-ray crystallography

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HarryHirsch
Not sure if this was due to a clash of personalities between Wilkins and
Franklin or due to gender issues. Considering that there were many women
active in British crystallography (Dorothy Hodgkin, Olga Kennard, Eleanor
Dodgson, Kathleen Lonsdale, to name a few) I think it really was a personality
issue, and the "white men" was unnecessary, even wrong.

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slitaz
I watched the video and then clapped at the end.

There has been tremendous effort to make the presentation and explain the
mechanics that led to the XFEL.

Highly recommended.

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ixtli
Incredible video. I’m a software engineer but I feel I know so much more about
physics now.

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abainbridge
I agree with all the other comments - this is an excellent video.

Does anyone know how the slides were made? Some of the animations are rather
lovely. They look like they were made by a professional TV media company. I'm
guess this is not the case.

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Gravityloss
He mentioned that protein crystals are hard to create. There have been
experiments to grow them in space. That possibility could open up soon.

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oever
Here's a collage of protein crystals grown in space in 2000.

[https://en.wikipedia.org/wiki/File:Protein_crystals_grown_in...](https://en.wikipedia.org/wiki/File:Protein_crystals_grown_in_space.jpg)

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andrewflnr
Worth watching just for the visualization of how accelerating electrons leads
to radiation emission.

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hughes
Anyone else having problems with the audio?

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qualitytime
Watched all the video.

Really Great.

Thank you!

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sprash
I still don't understand why we need such a thing. Every single interaction
that is involved with protein folding or any chemical or molecular process can
be calculated "ab initio" via QED (Quantum Electro Dynamics). So why not just
build big computers and be done with it? If there is any macroscopic effect
that can be exploited, we still can prove that the theory works and won't need
a super powerful FEL for it.

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robinhoodexe
The main problem is scaling. In quantum chemistry, you need electron
correlation to get accurate results (comparing your ab initio with
experiments) and these methods scale quite badly. Somewhat state-of-the-art
CCSD(T) (coupled cluster singles and doubles with triple excitations
approximated by perturbation theory) scales formally as N^7, with N being the
number of electrons in your system (somewhat simplified). Proteins are huge.
Even with some of the newest nearly linear-scaling coupled-cluster methods
(which utilize GPUs) running calculations on proteins takes extremely long
time. And this is _just_ electron correlation methods. We're still using the
Born-Oppenheimer approximation, not taking all excitaions into account, using
a finite size basis set, ignoring relativistic effects, not thinking about
time evolution and (most of the time) not considering (explicit) solvent
effects.

We are still a long way from modelling protein folding in solution with 100%
quantum mechanics. Luckily, classical molecular dynamics are quite good at
modelling biochemical systems (to a degree). There are a ton of errors that a
much bigger than quantum (and relativistic) effects anyway.

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sprash
Ok now I understand why we need such a thing, thank you very much. My
knowledge does not go beyond good old Hatree-Fock on that matter. I thought
this is a legitimate question because in theory this device is not build to
discover any new physics which I would expect from such a facility.

Edit: Followup question, is it possible to build a ProteinFoldingCoin? Can the
problems of theoretical chemistry formulated in a way that is hard to
calculate and easy to verify, hence replacing the useless sha256 calculations
in Bitcoin with something that makes sense?

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robinhoodexe
>is it possible to build a ProteinFoldingCoin?

I've thought about it, but don't think it's possible. Basically quantum
chemical methods like Hartree-Fock or Coupled Cluster is a question of finding
eigenvalues to some very very large matrices and/or solving non-linear
equation. Verifying a solution (such as electron correlation energy) can, to
my knowledge, only be done by using the result and checking if the equations
are still valid, which pretty much is just doing the whole work.

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chefandy
I admittedly didn't visit the link, but I think it's pretty sweet that i can
get one of these "electron lasers" for free.

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chefandy
wow, you folks hate jokes. It wasn't even an offensive one.

~~~
logfromblammo
Wordplay jokes are very low on the comedy sophistication scale, just above
puns, bodily functions, and inherently funny words.

HN is just a tough room. You really have to step it up a notch or two, just to
not get downvoted. For example, this is probably not quite good enough:

Electron emancipation is fine and good, but electrons will never _truly_ be
free until they have the vote.

