Brief items

With the end of the semester approaching and various grant deadlines, it's been a very busy time.  Here are some items I spotted this week (some new, some old):

• This article from Quanta about the "Einstein tile" is great - I particularly like the animated illustration.  This prompted some fun discussions with colleagues about whether there might be materials with structures like this, and what their properties would be, since they are ordered yet aperiodic yet not quasicrystalline.
• On twitter, I saw a link to this Nature Photonics paper that measures losses in what are designed to be topological photonic structures. The motivation behind such structures is that certain propagating optical modes are expected to be topologically protected from back-scattering.  Instead, the authors find plenty of back-scattering, and they raise the question of how useful topological protection is in practice.  Thought-provoking.
• Also on twitter, I saw this Nature paper, which uses ultrafast optics to look at Floquet effects with sub-optical-cycle timing resolution.   
• Lengthy article in Science about plagiarism and Ranga Dias.
• This article is about making a low-cost (€100) detector for electron microscopy, far cheaper than the hardware supplied by commercial SEM vendors.  I reiterate:  I think it would have enormous impact if someone could develop an SEM that is truly inexpensive (say less than $2000, so that many high schools and community colleges could afford one).  
• I had occasion to re-read the original paper by Little and Parks (1962) on what is now called the Little-Parks effect.  The transition temperature (inferred via the resistance in the transition regime) of a thin-walled superconducting cylinder oscillates with external magnetic field threading the cylinder.  The oscillations are periodic in magnetic flux with a period \(h/2e\), providing key evidence that the current in superconductors is carried by pairs electrons (or holes).  It's cool to see how they made a 1 micron inner-diameter Sn cylinder back before we had all the fancy modern fabrication techniques, reaffirming that GE Varnish is a wonder material. 
• SpaceX is going to try to launch their truly enormous rocket this coming week from Boca Chica, TX.  Like any first test flight, it has a good chance of failure, but if they can get this system to work as envisioned, it will truly be transformative in terms of payload to orbit.  Here's the link to their live webcast that starts Monday morning.

The problems and opportunities of data

We live in a world of "big data", and this presents a number of challenges for how we handle this at research universities.  Until relatively recently, the domain of huge volume/huge throughput scientific data was chiefly that of the nuclear/particle physics community and then the astronomy community.  The particle physicists in particular have been pioneers in how they handle enormous petabyte quantities of data at crazy high rates.

Thanks to advances in technology, though, it is now possible for small university research groups to acquire terabytes of data in an afternoon, thanks to high speed/high resolution video recording, hyperspectral imaging, many GHz bandwidths, etc.  Where things get tricky is, this new volume and pace are demands that researchers, universities, funding agencies, publishers, etc. are generally not equipped to handle, in terms of data stewardship.

I've written before about the responsibilities of various people regarding data stewardship.  Data from sponsored research at universities is "owned" by the universities, because they are held responsible by the funding agencies (e.g. NSF, DOE, DOD) for, among other things, maintaining accessible copies until years after the end of the funding agreements.  The enormous volumes of data that can now be generated are problematic.  With the exception of a small number of universities that host supercomputing centers, most academic institutions just do not have the enterprise-class storage capacity (either locally or contracted via cloud storage services) to meet the ever-growing demand.  Ordering a bunch of 8 TB external hard drives and keeping them in a growing stack on your shelves is not a scalable, sustainable plan.  Universities all over are finding out that providers can't really provide "unlimited" capacity without passing costs along to the research institutions.  Agencies are also often not fans of significant budgeting in proposals for long-term data retention.  It's not clear that anyone has a long-term solution to this that really meets everyone's needs.  Repositories like zenodo are great, but somewhere someone actually has to pay the costs to operate these.

Further, there is a thriving movement toward open science (with data sharing) and FAIR data principles - making sure that data is findable, accessible, interoperable, and resuseable.  In condensed matter physics, this is exemplified by the Materials Genome Initiative and its updated strategic plan.  There is a belief that having this enormous amount of information available (and properly indexed with metadata so that it can be analyzed and used intelligently), combined with machine learning and AI, will lead to accelerated progress in research, design, and discoveries.  

At the same time, in the US there are increasing concerns about data security, and coming regulatory actions about this.   University research administrators are looking very hard at all this, as is the Council on Government Relations, both because of chilling effects across the community and to push to make sure that Congress and agencies don't saddle universities with mutually incompatible and contradictory policies and requirements.  

Meeting all of these needs is going to be a challenge for a long time to come.  If any readers have particular examples of how to meet the needs of very large volume data retention, I'd appreciate the comments.

What do we want in a conference venue?

The APS March Meeting was in Las Vegas this year, and I have yet to talk to a single attendee who liked that decision in hindsight.  In brief, the conference venue seemed about 10% too small (severe crowding issues in hallways between sessions); while the APS deal on hotels was pretty good, they should have prominently warned people that not using the APS housing portal means you fall prey to Las Vegas’s marketing schtick of quoting a low room rate but hiding large “resort fees”; with the exception of In N Out Burger, the food was very overpriced (e.g. $12 for a coffee and a muffin in the Starbucks in my hotel); and indoor spaces in town generally smelled like stale cigarettes, ineffective carpet cleaner, and desperation.

I don’t think it’s that hard to enumerate what most people would like out of a conference venue, if we are intending to have in-person meetings and are going to spend grant money and valuable time to attend the meeting with our groups. (I’m taking as a given that the March meeting is large - now up to 12K attendees, for good or ill - and I know that’s so big that some people will decide that it’s too unwieldy to be worth going.  Likewise, I know that the logistics are always difficult in terms of the abstract sorting and trying to make sure that likely-popular sessions get higher capacity rooms.)

Off the top of my head, I would like:

• A meeting venue that can accommodate everyone without feeling dangerously crowded at high volume transit times between sessions, with a good selection of hotels nearby that don’t have crazy room rates.  (I know that the meeting growth already likely rules out a lot of places that have hosted the March meeting in the past.)
• A high density of relatively cheap restaurants, including sandwich places, close to the venue for lunch, so that a quick bite is possible without hiking a mile or being forced to spend $20 on convention center food.
• Actual places to sit (tables and chairs) to talk with fellow attendees.  Las Vegas had a much smaller number of these (indoors) than previous locations.
• Reasonable availability of water (much better these days than in the past) and not-outrageously-priced coffee and tea.
• Wifi that actually can accommodate the number of attendees; at some point in Las Vegas I basically gave up on the conference wifi and tethered to my phone.  Remember, many of us still have to get some level of work done (like submitting annoyingly timed proposals) while at these.
• Modern levels of accommodations for nursing mothers, childcare, facilities for those with disabilities or mobility issues, etc. 

Are there major items that I’m missing?  Do readers have suggestions for meeting sites that can hit all of these?  I am well aware that the APS is financially constrained to make these arrangements years in advance.  It can’t hurt to discuss this, though, especially raising concerns about problems to avoid.

Recent RT superconductivity claim - summary page

In the interests of saving people from lots of googling or scrolling through 170+ comments, here is a bulleted summary of links relevant to the recent claim of room temperature superconductivity in a nitrogen-doped lutetium hydride compound under pressure.  

• Dias's contributed talk at the APS meeting is here on youtube.
• Here is the promotional video put out by Rochester as part of the media release.  It odd to me that the department chair and the dean of the PI are both in this video.
• Here is the pubpeer page that has sprung up with people reporting concerns about the paper.
• The comments attached to the paper itself contain interesting discussion (though strangely an informed comment from Julia Deitz about the EDX data was repeatedly deleted as "spam")
• There was a lot of media coverage of this paper.  The Wall Street Journal was comparatively positive.  The New York Times was more nuanced.  Quanta had a thorough article with a witty headline describing the controversy surrounding the claim.  The APS had an initial brief news report and a more extensive article emphasizing the concerns about the paper.
• Experimental preprints have appeared looking at this.  The first observes a color change under pressure in LuH2, but no superconductivity in that related compound.  The second is a direct replication attempt, finding x-ray structural data matching the report but no superconductivity in that material up to higher pressures and down to 10 K.  Note that another preprint appeared last week reporting superconductivity at about 71 K in a different lutetium hydride at much higher pressures.
• A relevant and insightful talk from James Hamlin is here, from a recent online workshop about reproducibility in condensed matter physics.  Note that (as reported in this twitter thread) significant portions of Hamlin's doctoral thesis appear verbatim in Dias' thesis.  

No doubt there are more; please let me know if there are additional key links that I've missed (not every twitter comment is important).   

APS March Meeting 2023, Day 4 + wrapup

 My last day at the March Meeting was a bit scattershot, but here are a few highlights:

• In a session about spin transport, the opening invited talk by Jiaming He was a clear discussion of recent experimental results on spin Seebeck effects in the magnetic insulator LuFeO3. The system is quite complicated because the net magnetization direction depends nontrivially on the external field, leading to spin transport signatures with a complicated field orientation relationship.
• There was an invited session about 2D magnets, and Roland Kawakami gave a clear, pedagogical talk about how they have learned to grow epitaxially nice structures between van der Waals magnets (like Fe3GeTe2) and topological insulators (Bi2Te3).   This was followed by a tag-team talk by Vishakha Gupta and Thow Min Cham from Cornell, presenting some great results about spin orbit torque measurements coupling topological insulators and van der Waals magnets, where a gate can be used to dial around the chemical potential in the TI, leading to changes in the anomalous Hall effect.
• I did check out the history of science session, featuring a very nice talk about the 75th anniversary of the foundations of quantum electrodynamics by Chad Orzel, including a book recommendation that I need to follow up on.  

Overall, it was a good meeting, certainly the closest thing to a "normal" March Meeting since 2019.  I'm not a fan of Las Vegas as a venue, though.  The conference center was a bit too small (leading to a genuinely concerning jamming transition in the hallways at one point), the food was generally criminally expensive, and too many places indoors smelled like a combination of ancient cigarette smoke and ineffective carpet cleaner.   It will be interesting to see what the stats are like for things like the downloads of recorded talks and viewing of the virtual component of the meeting that happens in ten days.

APS March Meeting 2023, Day 3

There is vigorous discussion taking place on the Day 2 link regarding the highly controversial claim of room temperature superconductivity.  

Highlights from Wednesday are a hodgepodge because of my meanderings:

• The session about quantum computing hardware was well attended, though I couldn't stay for the whole thing.  The talk by Christopher Eichler about the status of superconducting qubit capabilities was interesting, arguing the case that SC devices can credibly get to the thresholds needed for error correction, though that will require improvements in just about every facet to get there with manageable overhead.  The presentation by Anausa Chatterjee about the status of silicon spin qubits was similarly broad.  The silicon implementation faces major challenges of layout, exacerbated (ironically) by the small size of the physical dots.  There have been some recent advances in fab that are quite impressive, like this 4 by 4 crossbar.  
• Speaking of impressive capabilities, there were two talks (1, 2) by members of the Yacoby group at Harvard about using a scanning NV center to image the formation and positions of vortices in planar Josephson junctions.  They can toggle between 0 and 1 vortices in the junction and can see some screening effects that you can't just get from the transport data.  Pretty images.
• Switching gears, I heard a couple of talks in an invited session about emergent phenomena in strongly correlated materials.  From Paul Goddard at Warwick I learned about charge transport in some pyrochlore iridates that I didn't realize had so much residual conduction at low temperatures.  See here.  Likewise, James Analytis gave a characteristically clear talk about interesting superconductivity in Ni(x)Ta4Se8 (arxiv version here), an intercalated dichalcogenide that has magnetism as well as re-entrant superconductivity up at the magnetic field that kills the magnetically ordered state.
• Later in the day, there was a really interesting session about measuring entropy, which is notoriously difficult to do.  As I've told students for years, you can't go to Keysight and buy an entropy-meter.  There was some extremely pretty data presented by Shahal Ilani using a variant of their new scanning probe technique.

Morning of Day 4 is being taken up by a bunch of other tasks, so the next writeup may be sparse.

APS March Meeting 2023, Day 2

I ended up spending more time catching up with people this afternoon than going to talks after my session ended, but here are a couple of highlights:

• There was an invited session about the metal halide perovskites, and there were some interesting talks.  My faculty colleague Aditya Mohite gave a nice presentation about the really surprising effects that light exposure has on the lattice structure of these materials.  One specific example:  under illumination, some of the 2D perovskite materials contract considerably, as has been seen by doing in situ x-ray diffraction on these structures.   This contraction leads to a readily measured increase in electron mobility and solar cell performance.  Moreover, the diffraction patterns show that some diffraction spots actually grow and get sharper under illumination.  This kind of improved ordering shows that this is not just some sort of weird heating effect.
• In a session about imaging, I caught an excellent talk by Masaru Kuno, who described his spectroscopic infrared photothermal heterodyne imaging.  The idea is elegant, if you have access to the right light source.  Use a tunable mid-IR laser that can go across the "fingerprint region" of photon energies to illuminate the sample in a time-modulated way.  If there is an absorptive mode (vibrational in a molecule, or plasmonic in a metal) there, the heating will cause a time-modulated change in the local index of refraction, which is then detected using a visible probe beam and a lock-in amplifier.  It was an extremely clear, pedagogical talk.
• I spent much of my time in the strange metal session where I spoke.  There were some very good (though rather technical) theory talks, trying to understand the origins of strange metallicity and key issues like the role of disorder.  

I had wanted to attend the session about superconductivity measurements in materials at high pressures, because of the recent and ongoing controversies.  However, the room was small and so packed that the fire marshal was turning people away all afternoon.  I gather that it was quite an eventful session.  If one of my readers was there and would like to summarize in the comments, I'd be grateful.

(BTW, it seems like this year there have been two real steps backwards in the meeting.  The official app, I am told, is painful, and for the first time in several years, the aps wifi in the meeting venue is unreliable to the point of being unusable.  Not great.)

APS March Meeting 2023, Day 1

Ahh, Las Vegas.  I will say, I think every APS March Meeting from now on should have a giant Ferris wheel right by the registration lobby.   

Here are a few highlights from what I saw after I arrived around lunchtime today:

• Given some of my current research, I spent a fair bit of time at the invited session about strange metals today.   All of the talks that I saw were very strong.  Andrew MacKenzie spoke about recent measurements of the Lorenz number in such materials (particularly Sr3Ru2O7) and made a persuasive case that strange metals do look different in their temperature-dependent thermal conductivity, because of very strong electron-electron scattering.  This is discussed in this recent review article.  
• In the same session, Brad Ramshaw showed very pretty angle-dependent magnetoresistance data on Nd-LSCO, an archetypal cuprate, arguing that the whole data set can be modeled very well assuming conventional quasiparticles and Boltzmann equation analysis (albeit with a funky combination of temperature-independent anisotropic scattering and strongly temperature dependent isotropic scattering).  His postdoc Gaël Grissonnanche expanded on this and looked at how such a model can also reproduce the linear-in-B magnetoresistance in this system.
• At the McGroddy Prize session, James Hone gave a very nice overview of the impressive body of work from Columbia over the years on all of the stackable van der Waals materials.  Some particular recent highlights included: (1) using deliberately oxidized WSe2 (into WOx) as a low-disorder, very high workfunction material that modulation dopes holes when stacked on a target layer of interest; (2) Using vdW material ferroelectricity to modulate superconductivity in MoTe2; in-progress work using an AFM + an hBN "handle" to bend a graphene "noodle" to get continuously tuned, clean moiré potentials; and electrostatically actuated sliding motion of monolayer vdW material.

Hopefully crowd control will be a bit better tomorrow.  The hallways seemed narrower than at past meetings, very crowded, and the site would benefit from more places to sit and have conversations.

APS March Meeting 2023 - coming soon

I will be attending the 2023 APS March Meeting in Las Vegas this week.  I will do my best to try to report on some highlights daily, though that may be more challenging than usual for me this time around (looming proposal deadline that I suspect all of my condensed matter faculty readers know about, plus some teaching-related work).  This is the first APS meeting in Las Vegas since 1986, when (according to legend) the APS was invited not to come back.  (Sorry for the web archive link - it would appear that the old PhysicsCentral content from APS is not online anywhere easily searchable.)  I'll be giving an invited talk on Tuesday which should be fun.  If people have suggestions of particular exciting sessions, please add them in the comments.

Science and how it will be practiced in the future

I just registered for an event that celebrates the 35th anniversary of a particular science and engineering program, and one question they posed was, to paraphrase, "Science has changed a lot in the last 35 years.  Please make three predictions about science in the next 35 years."  

I'd be curious for readers' views on this.  My quick take:

• There will be far more AI/machine learning/software agent-assisted activity.  That seems a certainty, and hopefully it may alleviate some repetitive drudgery in certain types of research.
• Hopefully I am wrong about this, but I have a feeling that we are still trending in the direction of a widening divide between "have" and "have not" research universities, in terms of having the financial resources to do leading science and engineering research.
• Foundation investments may be a growing portion of basic research support, for good or ill.  Governmental agencies will face increasing constraints on finances and pressure to concentrate more on short-term and applied work with some claimed quick benefit to economic competitiveness or national security.  

Thoughts?

Tour de force work: Bragg, diffraction, and diamond

There are some examples of scientific progress that just seem so far above and beyond the norm, it's almost jaw dropping in terms of the mental leap needed for the insight.  One example that I always liked to point out to first-year undergrads learning about gravity is Johannes Kepler in 1601-1609 analyzing Tycho Brahe's data by hand (obviously) and deducing that planets move in elliptical orbits and the associated laws of planetary motion.  Imagine staring at page after page of hand-written numerical tables and somehow seeing that.  

Left: X-ray diffraction from single-crystal 
diamond. Right: Bragg's calculation of where
the spots would be if diamond had what we
now know is the correct structure.

Another example from condensed matter physics is the 1912 discovery by William Lawrence Bragg, then 25 years old, that he could deduce the crystal structure of solids from the positions of the spots revealed on photographic film as the solid diffracted a beam of x-rays.  The very fact of diffraction of x-rays by crystals had only been found earlier the same year by von Laue and collaborators.  Bragg had the insight that interference effects due to the x-rays bouncing off different planes of atoms would determine the pattern of spots, as constructive interference only takes place for certain combinations of directions for a given wavelength of x-rays.  The image here is based on Figs. 11 and 12 from this paper, "The Structure of Diamond", by Bragg and his father (who built the diffractometer!).  That was published back-to-back with the more general (and single-author!) paper, "The Structure of some Crystals as Indicated by Their Diffraction of X-rays", where Bragg wrote what is now known as Bragg's Law and the prescription for finding the distance between adjacent planes of atoms.  Imagine looking at the smudgy spots on the photographic plates, having the "aha!" insight about the origin of the pattern, and having the raw computational prowess to just go ahead and calculate it.  Unreal.

Some interesting links - useful lecture notes, videos

Proposal writing, paper writing, and course prep are eating a lot of my bandwidth right now, but I wanted to share a few things:

• David Tong at Cambridge is a gifted educator and communicator who has written lecture notes that span a wide swath of the physics curriculum, from introductory material on mechanics through advanced graduate-level treatments of quantum field theory.  Truly, these are a fantastic resource, made freely available.  The link above goes to a page with links to all of these.
• In a similar vein, Daniel Arovas at UC San Diego has also written up lecture notes on multiple components of physics, though usually aimed at the graduate level and not all linked in one place.  These include (links to pdf files) mechanics, thermodynamics and statistical mechanics, condensed matter physics, nonlinear dynamics, the quantum Hall effect, and group theory (unfinished).
• I long ago should have mentioned this youtube channel (Kathy Loves Physics and History), by Kathy Joseph.  Her videos are a great blend of (like it says on the label) physics and history of science.  As a great example, check out the story of Ohm's Law.  I had never heard about the dispute between Ohm and Ampère (who didn't know about the internal resistance of batteries, and thus thought his experiments disproved Ohm's law).  
• This twitter thread pointing out that current in quantum Hall and related systems is not, in fact, purely carried by states at the sample edges, is thought-provoking.  

Cavities and tuning physics

I've written before about cavity quantum electrodynamics.  An electromagnetic cavity - a resonator of some kind, like your microwave oven chamber is for microwaves, or like an optical cavity made using nearly perfect mirrors - picks out what electromagnetic modes are allowed inside it.  In the language of photons, the "density of states" for photons in the cavity is modified from what it would be in free space.  Matter placed in the cavity, e.g. an atom, then interacts with that modified environment, even if the cavity is not being excited.  Instead of thinking about just the matter, or just the radiation by itself, in the cavity you need to include the light-matter interaction, and you can end up with states called polaritons that are combinations of matter + radiation excitations.  There are various flavors of polaritons, as there are different kinds of cavities as well as different kinds of matter (atoms vs. excitons, for example).

I just heard a nice talk by Angel Rubio about recent advances in applying cavity effects to both chemistry and materials properties.  For a recent discussion of the former, you can try here (pdf file).  Similar in spirit, there is a great deal of interest in using cavity interactions to modify the ground states (or excited states) of solid materials.  Resonantly altering phonons might allow tuning of superconductivity, for example.  Or, you could take a material like SrTiO3, which is almost a ferroelectric, and try to stabilize ferroelectricity.  Or, you could to take something that is almost a spin liquid and try to get it there by putting it in a cavity and pumping a little.

It's certainly interesting to ponder.  Achieving this in practice is very challenging, because getting matter-cavity couplings to be sufficiently large is not easy.  Never the less, the idea that you can take a material and potentially change something fundamental about its properties just by placing it in the right surroundings sounds almost magical.  Very cool to consider.

Condensed matter’s rough start

 I’m teaching undergrad solid-state for the first time, and it has served as a reminder of how condensed matter physics got off the ground.  I suspect that one reason CM historically had not received a lot of respect in the early years (e.g. Pauli declaring that solid-state physics is the physics of dirt) is that it began very much as a grab bag of empirical observations, with the knowledge that the true underpinnings were well out of reach at the time.  Remember the order of a few key discoveries:

• Dulong and Petit realize that the specific heats of solids are all about the same size near room temperature, in 1819.
• Seebeck discovers that applying a temperature gradient across metals generates a voltage, in 1822.
• Braun observes that a metal wire touching a lead sulfide crystal conducts much better in one current direction than the other (making what we now call a Schottky diode) in 1874.
• Hall finds that a magnetic field applied perpendicular to a current in a metal leads to a voltage mutually transverse to both the current and the field, in 1879. Two years later he also found that you can get a transverse voltage in a ferromagnet even in the absence of an applied magnetic field, the “anomalous Hall effect” which was not really understood until this century.
• Electrons are discovered in 1897.

A whole host of materials physics observations predate the discovery of the electron, let alone modern statistical physics and quantum mechanics.  The early days of condensed matter had a lot of handwaving.  The derivation of the Hall effect in the classical Drude picture (modeling electrons in a metal based on the kinetic theory of gases) was viewed as a triumph, even though it clearly was incomplete and got the sign wrong (!) for a bunch of materials.  (Can you imagine trying to publish a result today and saying, ‘sure, it’s the wrong sign half the time, but it has to be sort of correct’?)

That we now actually understand so much about the physics of materials is one of the great intellectual accomplishments of the species, and the fact that so much of the explanation has real elegance is worth appreciating.

News items for the new year

After I was not chosen to be Speaker of the US House of Representatives, I think it’s time to highlight some brief items:

• Here is a great blog post by a Rice grad alum, Daniel Gonzales, about flow to approach faculty searches.  I had written a fair bit on this a number of years ago, but his take is much fresher and up to date.
• My colleagues in Rice’s chem department have written a very nice obituary in PNAS for Bob Curl.
• It’s taken nearly 2000 years, but people seem to have finally figured out the reason why Roman concrete lasts hundreds to thousands of years, while modern concrete often starts crumbling after 30 years or so.
• Capabilities for quantum optomechanical widgets are improving all the time.  Now it’s possible to implement a model for graphene, following some exquisite fabrication and impressive measurement techniques. 
• From the math perspective, this is just f-ing weird.  For more info, see here.

Favorite science fiction invention?

 In the forward-looking spirit of the New Year, it might be fun to get readers’ opinions of their favorite science fiction inventions.  I wrote about favorite sci-fi materials back in 2015, but let’s broaden the field. Personally, I’m a fan of the farcaster (spoiler warning!) from the Hyperion Cantos of Dan Simmons.  I also have a long-time affection for Larry Niven’s Known Space universe, especially the General Products Hull (a single molecule transparent to the visible, but opaque at all other wavelengths, and with binding somehow strengthened by an external fusion power source) and the Slaver Disintegrator, which somehow turns off the negative charge of the electron, and thus makes matter tear itself apart from the unscreened Coulomb repulsion of the protons in atomic nuclei.  Please comment below with your favorites.

On another new year’s note, someone needs to do a detailed study of the solubility limit of crème de cassis in champagne.  Too high a cassis to champagne ratio in your kir royals, and you end up with extra cassis stratified at the bottom of your flute, as shown here.

Happy new year to all, and best wishes for a great 2023.

The difficult need for creativity on demand

Thoughts at the end of another busy year…. Good science is a creative enterprise.  Some stereotypes paint most scientists as toiling away, so deeply constrained by logic that they function more like automatons grinding out the next incremental advance in a steady if slow march of progress. In practice, originality and creativity are necessary to develop and grow a research program.  Some of this is laid out (paradoxically, in a methodical list) by Carl Wieman in this article here.   Picking the right open questions to address (hopefully ones that are deep and interesting to other people as well as you), and figuring out how to address them given the tools at your disposal, frequently requires intuition, leaps beyond incrementalism, and some measure of intellectual risk-taking.

One aspect of modern science as practiced today with which I find myself struggling is the issue of time. We live in a short-term world.  Grants are generally brief in duration compared to doctoral student timescales and the time it takes to tackle big questions.  There are many more demands on our time than in the past, and it seems like most funding sources profess to want fresh, new, ground breaking ideas that are both high-risk/transformative/disruptive and yet somehow very likely to produce rapid, high-profile glossy results.  Some also want to see brand new approaches to education and outreach each time.  Finding the time to think deeply about the science and the educational aspects, reinventing research programs like clockwork, is something that I find very challenging.  One answer is, since creativity doesn’t generally respond to on-demand calls, always be thinking and noodling on ideas, but that’s much easier to say than to do consistently.   I’d be curious to hear others’ strategies for dealing with this; while I’m pretty set in how I work at this point, a discussion could be fun and useful.

Brief items - LOC, GPT, etc.

 This year was a busy one and my overall posting rate is down.  Hopefully the coming year will be a bit less frenetic, but who knows.  A few brief items:

• First, in the odd self-promotion department, this blog is officially going to be indexed by the Library of Congress as part of their Science Blogs Web Archive.  This is another sign that I am officially ancient in blogging terms.  This blog has never had the huge readership of some, but thanks to you for raising it above whatever the threshold of notice is for this.
• This was a cute story.  Folks at ETH have shown that a thin, barely percolating layer of gold can act as an anti fogging coating on glasses, since it can locally heat up due to its infrared absorption, while still being sufficiently transparent for use in eyewear.  At the risk of costing myself a lucrative potential patent, it seems to me that you could do the same thing using TiN, which has similar near-IR optical properties, and should be easy to integrate with the TiO2 coating that the researchers already use.  
• In a headline that is not a repeat from September, there is a new contender for world’s largest dilution refrigerator under construction, this time from FermiLab.  Multiple quantum computing platforms benefit from the sub-100 mK temperatures, so it’s not surprising to see efforts along these lines, but 5 cubic meters of sample chamber seems a bit much.  Time to invest in my Canadian 3He futures.
• I’m glad to see that someone has been thinking like my sci-fi-loving brain, and working out whether gravitational wave detectors could be used to detect evidence of some types of interstellar spacecraft.  While the paper concerns conjectural accelerating planetary-mass ships, certainly exotic propulsion ideas (warp drives, wormholes) would also have gravitational radiation signatures.
• Speaking of science fiction, like a lot of people I spent some time this week playing with chatGPT, the language model that may be the end of high school English essays, college admissions essays, and quite probably a lot of jobs.  Its output is uncanny and worrying, especially since it has no problem just brazenly lying and making up sources.  (For fun, see what happens if you ask it to explain why 51 is a prime number.). Still, it’s hard not to feel like we are right at some threshold, where expository and creative writing, historically the province of at least somewhat educated humans, is no longer ours.  This could mean great things for education (I asked it to explain Stokes’ theorem to me, and it did a pretty nice job), but it could mean terrible things for education (why learn to write well when a free tool can do a decent job for you?).  The calculator and computer did not eradicate math education or math literacy, so hopefully we will reap more of the positives than the negatives.  This post was written 100% by me, btw, with no GPT assistance, though remember that chatGPT lies….
• At the risk of being deemed a dangerous website by Twitter, where I am here, I’m on a mastodon instance now as well.  Sciencemastodon.com was started by Charles Seife and hosts a bunch of scientists and science journalists.

The fusion story of the day

There is a press conference going on right now announcing a breakthrough at the National Ignition Facility at Livermore.   The NIF is an inertial confinement fusion facility that uses 192 laser beams to compress a fuel pellet containing deuterium and tritium.  The pellet is inside a gold hohlraum, and it's really the x-rays from the gold that do a lot of the heavy lifting in this experiment.  The claim is that the energy output from the D-T fusion (which comes in the form of energetic helium nuclei, 14 MeV neutrons, and x-rays) has now exceeded the energy input from the lasers.  That's clearly necessary if there is ever to be any hope of using this approach to generate actual electricity, but it is far from sufficient. 

There is some very interesting materials science at work throughout the project that bears on this.  Right now, the lasers used in the NIF are based on doped glass amplifiers, and those get very hot under use, so that there needs to be hours between shots.  Also, they basically rebuild the sample mounting for the hohlraum after each shot.  This is fine for proof-of-concept physics experiments, but it's very far from a workable power plant.  

This is an exciting time for fusion research, in that there is a fair bit of activity, including startups.  (Note also that some of these approaches are aiming for scales closer to US Navy sized, like 20 MWe, rather than city power which is more like 2 GWe.)   To give a sense of my age and the timescale for these projects, when I was an undergrad, I spent a summer doing heat transfer calculations for the cable-in-conduit conductors for the D magnets for ITER.  That was in 1992.  The cliché is that fusion is always 20 yrs away, but we should know considerably sooner than that whether the startup approaches are likely to get there.  

The wormhole kerfuffle, ER=EPR, and all that

I was busy trying to finish off a grant proposal and paper revisions this week and didn't have the time to react in realtime to the PR onslaught surrounding the recent Nature paper by a team from Harvard, MIT, Fermilab, and Google.  There are many places to get caught up on this, but the short version:

• Using their Sycamore processor, the experimentalists implemented a small-scale version of the SYK model.  This is a model that has many interesting properties, including the fact that it is a testbed for holography, in which a bulk system may be understood by the degrees of freedom on its boundary.  For an infinitely large SYK system, there is a duality to a 2D gravitational system.  So, a protocol for moving entanglement in the qubits that make up the SYK system is equivalent to having a traversable wormhole in that 2D gravitational system.  
• The actual experiment is very cool.
• The coverage in the press was extensive (Quanta, NY Times, e.g.).  There was a lot of controversy (see Peter Woit's blog for a summary, and Scott Aaronson for a good take) surrounding this, because there was some initial language usage that implied to a lay-person that the team had actually created a traversable wormhole.  Quanta revised their headline and qualified their language, to their credit.  

Rather than dogpiling on the media coverage, there are two main points at issue here that I think are worthy of discussion:

1.  What do we mean when we say that we have experimentally implemented a model of a system?     When atomic physicists use ultracold fermionic atoms to make a 2D lattice governed by the Mott-Hubbard model (like here and here), we say that they have made a Mott insulator.  That same model is thought to be a good description of copper oxide superconductors.  However, no one would say that it actually is a copper oxide superconductor.  When is a model of a thing actually the thing itself?   This is at the heart of the whole topic of quantum simulation, but the issue comes up in classical systems as well.  My two cents:  If system A and system B are modeled extremely well by the same mathematics, that can give us real insights, but it doesn't mean that system A is system B.  Better language might be to say that system A is an analog to system B.  Physicists can be sloppy with language, and certainly it is much more attention-getting to editors of all stripes (be they journal editors or journalism editors) to have a short, punchy, bold description.  Still, it's better to be careful.  
2. What do theorists like Lenny Susskind truly mean when they claim that entanglement is genuinely equivalent to wormholes?  This is summarized by the schematic equation ER = EPR, where ER = Einstein-Rosen wormhole and EPR = Einstein-Podolsky-Rosen entanglement.  I think I get the core intellectual idea that, in quantum gravity, spacetime itself may be emergent from underlying degrees of freedom that may be modeled as sorts of qubits; and that one can come up with fascinating thought experiments about what happens when dropping one member of an entangled pair of particles into the event horizon of a black hole.  That being said, as an experimentalist, the idea that any kind of quantum entanglement involves actual Planck-scale wormholes just seems bonkers.  That would imply that sending a photon through a nonlinear crystal and producing two lower energy entangled photons is actually creating a Planck-scale change in the topology of spacetime.  Perhaps someone in the comments can explain this to me.  Again, maybe this is me not understanding people who are being imprecise with their word choice.