Papers and news items

First, some science, clearing out a number of papers and articles that I've been collecting for some time in my far-too-numerous browser tabs:

• I've written before (here) about dimensional analysis and similarity, techniques commonly used in the engineering world that can seem quasi-miraculous at times.  This paper gets into why this approach works, and different categories of physical similarity.  I'd mentioned it when the book came out, but this kind of thinking is also a key component of Anthony Zee's Fly by Night Physics.
• This review article is about fundamental limits in photonics and electromagnetics.  This is a very handy review that I'm going to point my students toward.
• On a lighter note, a colleague pointed me to this collection of (AI-generated) songs related to thermodynamics.    
• Speaking of thermodynamics, here is a recent paper about the thermodynamic description of wealth inequality (treating the flow of money in a physics formalism - see here for a prior discussion.).  Edging closer....  
• There was a nice post on substack about Wojciech Zurek's approach to decoherence in quantum mechanics (quantum darwinism).   Cleanly written.  
• Along these lines, this paper is a survey/guide to issues in quantum foundations and interpretations of quantum mechanics.
• Lastly, Jim Freericks has a new quantum mechanics textbook out (for free!), with the challenging idea of making the subject accessible without calculus or differential equations.  (I'm jealous.  My textbook's UK publisher would not let me use Steve Martin's quote for a chapter epigraph, but Prof. Freericks was able to do it - well played.)

And more news/policy-related items:

• The presidential science advisor and head of OSTP, Michael Kratsios, appeared before the House science committee this week, timed to be coincident with the release of OSTP's new report, "Science: A New Golden Age".  A lot has already been written by many people about this report, which contains a number of actual proposals, some good and others of varying degrees of vagueness/underwear gnomes-level magical thinking.  Two pretty good (in my view) takes on this are this article in ars technica and this policy piece by Cole Donovan (former OSTPer).  It's important to remember:  This is a policy document, not something that has automatic impact, no matter how the Wall Street Journal frames its reporting on this.  (Hint:  This document alone does not somehow grant the president the authority or ability to redirect $200B in research funding.  Maybe their reporting on this would be better if they hadn't laid off all their science reporters.)  It's important to pay attention to what is said here, without giving it more oxygen than it deserves.  It's also unclear whether anything OSTP is saying and doing is aligned with what OMB is doing.  Declaring a new golden age of science while simultaneously proposing large cuts in all the science agencies is not exactly a sign of coherence.  Derek Lowe at Science has it right, essentially.  Nature reports that the mid-year budget clawbacks from NSF are apparently going toward some OSTP grand challenge initiative, something about which Kratsios denied all knowledge when talking to the House committee.  
• Holden Thorpe also raises a key point, that universities need to get their collective act together, have a plan about the future of research, and act on it, rather than scrambling for remaining scraps while trying hard not to be seen.  The AAU is important, but hoping that the AAU will accomplish difficult tasks without individual institutions having to take a public stand is unlikely to be successful as strategy.  Organizations like SUFS, UCS, and FAS are pushing the agenda; universities need to decide how they want to play this.
• The first round of DOE Genesis Mission awards were announced this week in DC as well.  
• SpaceX had a pretty successful test flight of their huge rocket, culminating with unexpectedly soft-landing the second stage ("Starship") in the Indian Ocean.  If they really can get this working at the level of reliability and reusability they've done with the Falcon 9, it truly would be game-changing for large-scale payload to orbit.  (Data centers in space still make no sense btw.)
• This week was also a big one in the world of mathematics, with an AI tool (Claude Fable) being used to find a counterexample to the previously outstanding Jacobian Conjecture.  Here is a write-up by Fields medalist Terence Tao, and here is a discussion among other mathematicians.  That wasn't alone.  Here (link to x) is a counterexample being found to a conjecture in graph theory, and it approaches "proof by intimidation" - the human basically harasses and bullies the AI tool into the solution without contributing any intellectual argument.  It seems like it's only a matter of time before some major theoretical physics result gets generated by these tools, though it's important to note that many physics problems are NP-hard/just not integrable.  AI tools are impressive, especially since they're trained on the entire corpus of technical literature, but they are not miraculous:  Claude can't somehow factor large numbers efficiently, or exactly solve the many-electron interacting Hamiltonian for the Hubbard model, because those are truly difficult problems.  Update:  Here are Terence Tao’s slides about AI and the future of mathematics.  As usual, these are excellent.

A brief serious note about mental health and well-being

I've been blogging for 21 years now (!!), and over that time I've had a wide variety of comments on here, but there have been a couple of anonymous ones in the last few weeks that really worried me.  It's the internet, so you can't readily tell when someone is trolling, but these made me concerned for the safety and emotional state of the commenter.   Just remember, there is always someone to talk to who is ready to listen, and we're all better with you than without you.  The 988 hotline (https://988lifeline.org/) is available 24/7/365, free and confidential.  Please take care.

A few optics/metamaterials highlights from META 2026

This past week I attended META 2026, the 16th International Conference on Metamaterials, Photonic Crystals and Plasmonics, at Trinity College, Dublin.  This was the first time I've ever gone to this conference, which has grown from somewhat blurry beginnings to a ~ 900+ person annual event.  Here are a few scientific highlights:

• Metasurfaces, built up from spatial arrays of dielectric (or sometimes semiconductor or plasmonic) resonators called "meta-atoms", have matured into very impressive, versatile tools.  In her plenary talk, Ruwen Peng from Nanjing showcased different approaches, combining angularly rotated meta-atoms ("Pencharatnam-Berry") and size-modulated meta-atoms.  The result can produce polarization-entangled photon beams, entangle photon spin and orbital angular momentum for quantum key distribution, and do full entanglement distribution over many channels.  Similarly, Federico Capasso gave a very impressive talk about the progress in the field, from visible wavelength flat optics ten years ago to compact platforms for sophisticated quantum tomography.
• Nikolay Zheludev gave a great overview about combining measurements + machine learning estimators (e.g., here) to achieve effective optical resolution far better than conventional limits.  This can be used to make optics-base estimates of nanowire lateral displacements down to the 100 pm level, for example.  Rather than looking at the flow of energy in an optical imaging system, one can look at the flow of Fisher information regarding the object being imaged.
• There were a series of talks throughout the meeting about chirality of optical scattering, what this means, and what it can lead to (including enantiomer-selective imaging and chemistry).  Note that it's important to distinguish between intrinsic chirality (e.g., the object scattering the light has a real structural handedness), extrinsic chirality (the object scattering the light is not chiral, but the experimental arrangement to do and measure the scattering introduces chirality into the measurement), and chirality in the fields themselves (think swirling Poynting vectors locally) that don't necessarily extend to the far field.  There are some neat probes of local effects, like this use of local polymerization.
• Roman Quidant gave a talk about metalenses that are also optomechanical structures (e.g., use a pump beam to excite mechanical deformation of the metalens to steer the focus of a probe beam).  This lets you do some pretty neat things, like control the sign of optical forces by dynamically tuning the relative importance of momentum transfer (pushing objects with light by direct momentum kick from photons) and polarization forces (the classical optical tweezer situation where polarizable objects "seek" regions of high intensity).  This can enable feedback control to do optical cooling of trapped, levitated particles, potentially down to the quantum level.
• Alessandra Boltasseva presented a variety of recent advances, including a look at how plasmonic ceramics like TiN and HfN have properties that can be dramatically tuned as their thickness gets down to the few-unit-cell level, a regime she and collaborators term "transdimensional" (to distinguish from atomically thin 2D van der Waals materials).  The possibility of Wigner crystallization in such systems is exciting, though disorder is a likely complication.  

• 

  A 4-channel wavelength division multiplexer
  made from etched Si3N4, from this paper.

  Jeremy Baumberg talked about building metamaterials out of molecularly-spaced nanoparticles, and how this has opened up real opportunities for chemical sensing based on surface-enhanced Raman and infrared absorption, as in this example.  Neat stuff.
• There were multiple talks about metasurfaces for nonlinear optics, including one by Igal Brener on cool ways to use GaAs metasurfaces to produce entangled photon pairs via bound states in the continuum.  
• Likewise, there were a number of presentations about inverse design, where computational tools are used to produce very funky looking structures which can act as, e.g., multichannel routers of optical signals.  Jelena Vuckovic presented an overview of this, showing how it can be done at scale to produce a chip that acts as a 1 TB/s optical router.  Structures produced this way always seem to me like some kind of eldritch geometry out of HP Lovecraft (see figure), but they work.  
  

As always, apologies to those whose work I didn't mention above; my note-taking was pretty uneven.

(I am trying to strike a balance between talking and educating people about science, which is basically the point of this blog, and keeping people informed/voicing some of my personal opinions about the crisis in the US research ecosystem (arguably the most consequential challenge facing US researchers today, with long-term implications that will be felt for many years).  There is still very exciting work being done in nanoscience, the physics of materials, etc. - we are just facing a future where if current trends continue the major advances may increasingly happen outside the US.)

Bad to worse at NSF? (July 2026 edition)

When I wrote this post last month, I really did not want it to be first in a series.

The inciting incident to write that post was a news article in Science reporting that there have been draconian ~ 30% cuts in present fiscal year budgets within the NSF.  Program officers were instructed to keep this confidential and not talk about it with PIs.  The rumor was that this funding would go to support the TIP directorate and its activities, particularly the "X-Labs".  

Now Dan Garisto has broken this story in Nature. For some, this is behind a paywall, so let me hit the highlights.

• "NSF staff members — who asked to remain anonymous out of fear of retaliation — and an internal NSF ledger seen by Nature suggest that the NSF plans to claw back around US$500 million that has already been distributed to grant-making divisions. "
• "Several NSF staff members told Nature that at least some of the funds will be funnelled to another project, a brainchild of the White House OSTP."
• "Even though programme officers have less to spend than they had expected, those who spoke to Nature are unsure how many new grants will make it out the door. “They could make it through if the process is allowed to work without interference or interruption,” one staff member says. But most of “the process is now a black box and unpredictable”. "
• "NSF staff members estimate that if the withdrawals are finalized, hundreds more proposals that have been recommended for funding across the engineering, computer and information science and engineering, and maths and physical science directorates would need to be sent back to programme officers for revision. Some proposals would be held until a later date when funds are available. Others would have their budgets reduced, and some would simply be declined."
• "Staff members say that they are frustrated by the planned diversion of funds and the lack of communication about the agency’s spending. “We don’t know where the money’s going or what’s going on,” says one staff member. Programme officers are not allowed to pass on what they know to researchers. “We cannot communicate to the community at all. We’re forbidden.”"

Basically, this reporting confirms the unprecedented mid-fiscal-year cuts; confirms that there is zero transparency about this with the community and even within the agency; and reveals that the funds are apparently being diverted to some mysterious OSTP project.  

To get a sense of scale, consider a typical program within MPS, with an annual budget of around X dollars.  About 20% or more of those funds are "mortgaged", set aside for ongoing already-funded projects, leaving 0.8X dollars for new awards.  Now, however, there is a 30% cut in the middle of the fiscal year, so the resources now available for new awards are 0.7X-0.2X = 0.5X.  The number of new awards therefore has to be cut by 37.5% relative to last year.   

This is a huge deviation from what Congress appropriated, seemingly being steered at the direction of the White House.  Will Congress care, or will the majority just give this power to the executive branch?  Is anyone going to disclose what the mystery project is?  Is any major national media outlet going to report on this?

I will post more science soon, I promise, and I hope that I don't have more posts in this series.

OMB proposed rule changes - act now

For non-US folks, feel free to skip. 

For US folks:  The Office of Management and Budget, which for much of its history has been a comparatively uncontroversial element of the executive branch, has set rules and guidelines for how many executive-branch agencies conduct business and interact with, e.g., universities.  For the purposes of how the research ecosystem operates, the most relevant is OMB's "Uniform Guidance" about how grants and contracts work.  Periodically these rules are updated for various reasons, including the goals and policies of the presidential administration.  The standard way this works is that the proposed changes are published in the Federal Register; there is a public comment period; OMB makes revisions and then publishes the new rules.  In principle, Congress can act to override or prevent rule changes, but without the agreement of the President, this is an extremely challenging path.

OMB has proposed sweeping changes to the Uniform Guidance, summarized here.  These proposed rule changes are huge deviations from previous practice.  For example, they would have all final grant decisions made by political appointees or hires of the executive branch (rather than, e.g., agency subject matter experts); grants could be cancelled at any time for essentially any reason (completely undefined insufficient support of the president's priorities), with no appeal process; international collaborations would be severely curtailed. That's just three for starters.  Note that this would also go beyond just the public research enterprise - it would allow the executive branch to cancel funding for things like bridges, roads, schools, agriculture, etc. for undefined political reasons.  It would be a huge transfer of power from Congress to the presidency.  Here is another summary by the AAU.  Here is an editorial essay from ars technica.  

The public comment period on this runs until July 13.  Here is a link where you can make a comment.  Here is a guide for how to be effective at this from Stand Up for Science.  The APS has a tool for helping people to comment about specific aspects of the rule changes.  It is also a good idea to contact congressional delegations (representatives, senators).  

It's important to have a clear public record about the proposed changes.  They may try to implement these regardless, but if so, there will be a continued fight over this in Congress and through the courts.