Congrats to Alán Aspuru-Guzik for landing a spot on MIT Tech review’s 2010 Young Innovators under 35:
In theory, quantum mechanics should offer perfect understanding of some of the most interesting events in chemistry–for example, the behavior of excited electrons, which controls such things as photosynthesis in plants. In practice, however, the necessary calculations are far too difficult for even the most powerful computers. So approximations must be made, especially when larger molecules such as proteins are involved.
Alán Aspuru-Guzik, a theoretical chemist at Harvard, is developing methods that could one day do away with the need for approximations altogether–and lead to better drugs or solar cells.
Hey I didn’t know Alán could supply me with better drugs 😉
Dave, I too am a big fan of molecular dynamical simulation in general, and Alán Aspuru-Guzik’s work in particular.
Like most modern-day quantum chemists and condensed-matter physicists (and even biologists), Alán works not on a Hilbert state-space, but on a product state-space. These state-spaces are a terrific place to work, for reasons that are reviewed on Dick Lipton’s blog, under Dick and Ken Regan’s excellent topic “Quantum Algorithms A Different View—Again.â€
The short summary is that there are solid reasons to anticipate that “some barriers in computational complexity are going to fall, and others are going to be evaded … and in consequence, new opportunities are opening for everyone.â€
The ongoing faster-than-Moore’s-Law advances in quantum chemistry capabilities provide us with an excellent illustration of how (and why) so many long-established barriers in computational complexity now are falling (or being evaded).
In this regard, the workshop Barriers in Computational Complexity starts tomorrow, sponsored by Princeton’s Center for Computational Intractability.
Speaking as someone who is neither presenting nor attending, but nonetheless has a keen interest in these topics … this is going to be a terrific workshop.
`Cuz heck, Dave … falling barriers … evaded problems … new opportunities … what could be more fun than *that*?
Neil B, just look up three letters: DFT
(density functional theory; the Wikipedia article is well-written).
Does DFT work amazingly well?
Heck yes.
Do we understand why it works so well?
Heck no.
Could I ask if I get this issue in atomic physics and thereby chemistry right: the outer electrons are shielded from nuclear charge by inner electrons. But since the electrons are in “clouds” formed by quantum distribution of wave functions, it isn’t as crude as e.g. the outer lithium electron being just like an electron orbiting one proton, right? So is the effective field an electron moves in, like the combination of the nucleus plus the field from other electrons as a charge distribution imagined as being spread over the “cloud” distribution? There has to be some effective charge to determine the energy levels, and we can get those.
If so, it seems to me that shows that the wavefunction is “real” beyond just being the substrate for measurement statistics according to the Born rule. It’s real because it determines the effective field distribution for other particles. (Well, all that abstract ruminating about the measurement problem does seem to pretend that the particle as WF has no effect on anything else until it “hits” something.)
I haven’t seen that expressed before. Yet indeed, even the basic point that electrons need to fit an integer number of waves into an orbit, shows there is more to being a wave than just determining measurement statistics. Just food for thought in addition to my basic question. tx
Thanks John. That seems to work about as I described. The larger import is, then it shows that wavefunctions aren’t just about “measurement” since they determine the structure and energy levels of atoms and molecules. So you can’t say, WFs are just a way of talking about e.g. where we might find an electron if we are specifically “looking for one” with a detector, directly.
David,
Thanks for the post! I am happy, very happy, of course. Now, more pressure to keep doing small experiments and moving along. It sucks that I did not get to talk to you more in Cincinnati.