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Free electron laser – A fourth-generation synchrotron light source
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All the comments and stories posted to Hacker News that reference this video.Free Electron Lasers...or why we need 17 billion Volts to make a picture.
https://media.ccc.de/v/34c3-8832-free_electron_lasers
HN discussion: https://news.ycombinator.com/item?id=16028723
Wouldn’t it be awesome to have a microscope which allows scientists to map atomic details of viruses, film chemical reactions, or study the processes in the interior of planets? Well, we’ve just built one in Hamburg. It’s not table-top, though: 1 billion Euro and a 3km long tunnel is needed for such a ‘free electron laser’, also called 4th generation synchrotron light source. I will talk about the basic physics and astonishing facts and figures of the operation and application of these types of particle accelerators.
Most people have heard about particle accelerators, most prominently LHC, at which high energy particles are brought to collision in order to study fundamental physics. However, in fact most major particle accelerators in the world are big x-ray microscopes.
The latest and biggest of these synchrotron radiation sources which was built is the European XFEL. A one billion Euro ‘free electron laser’, based on a superconducting accelerator technology and spread out 3km beneath the city of Hamburg. The produced x-ray pulses allow pictures, for example from proteins, with sub-atomic resolution and an exposure time short enough to enable in-situ studies of chemical reactions.
This talk aims to explain how particle accelerators and in particular light sources work, for what reason we need these big facilities to enable new types of science and why most of modern technology would be inconceivable without them.
A talk was given at the last CCC about free electron lasers, and in it the speaker talks about using diffraction to image chemical reactions. It's great watch.
⬐ NoneNone
For anyone looking for just the money diagram, ctrl+f "SOMEONE GETS IT RIGHT" in the link above.I first saw a version of that diagram just a couple of months ago at 34c3 in this _excellent_ talk on synchrotrons and free electron lasers[1] which delivered more than one such "aha!" moment. It's a great diagram, and it's a very worthwhile talk.
⬐ wbeatyhttp://amasci.com/miscon/coherenc.html#pinhole
⬐ mrybczynCCC.DE is slow for me, here's a youtube link to same video. Worth watching!⬐ None⬐ moritzsimonNoneI 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!⬐ TrueTom⬐ ralfdIt would've been even better without the unnecessary political commentary.⬐ None⬐ pasbesoinNone⬐ ginkoI was at the talk. What political commentary are you even talking about?⬐ simplyfantastNot 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.
⬐ pizzathe snubbing of rosalind franklin seems pretty apolitical to me - she had died, and there are no posthumous nobels. still a damn shame she isn't more of a household name, though.⬐ epmaybeWhat sort of political commentary on nejm are you referring to? I usually only read articles if I find them elsewhere, so I don't know much other than that it is a well respected journal in the medical community.⬐ frostburgSilence is political too, you just don't notice because you agree with it.I have a friend who worked on the construction of the CMS at CERN. Calibration, actually.He has a similar ability to very clearly explain the technology and what it is trying to accomplish. And an innate curiosity or interest that causes him to learn that -- beyond just his specific technical area.
In other words, some engineers are very effective networkers and communicators.
When I stop to think about it, they have to be, to ever succeed in building such a large and complex device -- in the company and at the behest of so many other disciplines, both practical and theoretical.
P.S. I should add that he does this with everything that really interests him and/or that he is doing. It's not confined to one topic or things he formally works on.
P.P.S. This may be a "Captain Obvious" comment; nonetheless, the presentation reminded me of him.
And of how some comment science stereotypes really are far from the mark.
⬐ ethbroMy personal observation is that experimental physicists seem to be better (on average) at this than other disciplines.Maybe something about having to deal with the physical world?
⬐ QAPereoIt depends... Dirac is a counterexample, while Bohr is a supporting example. It may just be that experimentalist who can explain their ideas with clarity and passion are the ones we notice first/most?⬐ stefco_⬐ nine_kDirac and Bohr were both theorists, not experimentalists! But you're right that it varies within disciplines.I'm an experimental physics Ph.D. student working on LIGO, and I have also found that experimental physicists are often very good at motivating engineering from top to bottom. I think having depth of knowledge is part of it. My advisor has told me that some of the best experimentalists have sufficient depth of expertise to be theorists. I can't comment on how this compares to other fields (since I haven't worked outside of academia) but I have been very satisfied with how eloquent and deeply informed experimental physicists usually are.
Experimental physics require large teams, thus communicators are more probable to be seen.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.⬐ AbrahamParangi⬐ slitazWhile 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
⬐ HarryHirschNot 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.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.
⬐ ixtliIncredible video. I’m a software engineer but I feel I know so much more about physics now.⬐ abainbridgeI 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.
⬐ GravitylossHe mentioned that protein crystals are hard to create. There have been experiments to grow them in space. That possibility could open up soon.⬐ oever⬐ andrewflnrHere's a collage of protein crystals grown in space in 2000.https://en.wikipedia.org/wiki/File:Protein_crystals_grown_in...
Worth watching just for the visualization of how accelerating electrons leads to radiation emission.⬐ hughesAnyone else having problems with the audio?⬐ qualitytimeWatched all the video.Really Great.
Thank you!
⬐ sprashI 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.⬐ dekhn⬐ chefandyYour premise, while theoretically true, is not practicable in reality. To compute the realistic trajectory (more correctly: to estimate the probability of all the transitions between all the states to build up the PDF) would require multiple universe-lifetimes to calculate with enough accuracy to replace what an xFEL can tell you.It's not just about building bigger computers. If it were, we would make that investment. If you look at the QED and QC calculations done on the world's largest supercomputers, they're not that inspiring.
⬐ vkreso⬐ jessriedelExactly. Outsourcing calculations to the rest of the universe is via such experiments is a better alternativeThe economy is just made of humans and equipment, which also obey the rules of QED. We should get rid of all these useless economists taking data and just simulate everything!⬐ robinhoodexeThe 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.
⬐ sprashOk 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?
⬐ 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.
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.⬐ chefandy⬐ awfulwow, you folks hate jokes. It wasn't even an offensive one.⬐ logfromblammo⬐ 24gttghhWordplay 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.
⬐ chefandy⬐ KoshkinCrowd of stiffs is stiff. Got it.Just as at work, I think a good joke is fine - as long as it comes along with some positive content. Otherwise it's just a distracting, meaningless noise.The use of the laser by non-profit entities is free, but one must write quite the sophisticated (I'm assuming) proposal/experiment to be undertaken in order to actually be given permission to use it. The time and effort required there is of course not free.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.⬐ ginko>Bremstrellung (sp?)
