Hacker News Reader

In terms of progress on fundamental physics (i.e., ignoring things like material science), this is a very slow crawl on any sensible absolute scale, and certainly vastly slower than progress was made up until the 1970s. With respect, I think you're just renormalizing to the glacial pace we've come to expect.

The Standard Model (including the yet-to-be discovered Higgs and top quark) was completed in the mid '70s around when the bottom and charm quark were found. The pace of discovery of new fundamental particles has clearly slowed dramatically; the top quark was in 1994 and Higgs was just a couple of years ago, with serious pessimism that anything else will come out of the LHC (even with the luminosity upgrades). The existence of an LHC successor is uncertain, and even if it is built it is unlikely to find anything new.

The solar neutrino, compared to just about any other fundamental physics question in the 20th century, is boring. It was solved by adding a few additional free parameters to the SM with little conceptual insight and few implications for further post-SM physics. As you and I commented elsewhere, pentaquarks are a neat window into low-energy QCD, but they aren't new fundamental physics.

Precision cosmology's biggest result was to confirm the ad hoc and simplest inflationary models from the 1980's, with little hope in the near-term future to do anything besides rule out poorly motivated variations designed explicitly to be testable. What is the inflaton like, and what does it do besides adjust a couple of parameters in the CMB? No one knows, and know one has a serious expectation of finding out anytime soon.

None of this, obviously, means that these meager accomplishments weren't hard or that the people who made them aren't extremely clever. But they are undeniably less exciting then what was see before I was born in 1985, and pale in comparison to the absolute revolutions of the first half of the 20th century (quantum mechanics, relativity, GR, field theory).

I really want to call this out:

> huge swaths of parameter space (i.e. possible theories) have been ruled out.

This is the sort of comment that only us physicists can say with a straight face. Parameter space is bounded only by one's cleverness and stamina. Ruling it out says very little about reality because most proposals have very little a priori probability. The entire industry of constructing complicated models and then ruling them out is the lamest kind of progress I can imagine. Perhaps the open questions have really just gotten so hard that this is the best that can be hoped for. But we should be honest that this is essentially like hitting a brick wall and digging into it with spoons.

I agree that there's some renormalizing taking place.

From the particle physics end, the revolution stopped because accelerator technology stalled out. If the laser-wakefield (or similar) accelerators can pan out, there may be a resurgence of the 1950's era of progress.

Just because the Standard Model happens to have panned out doesn't mean that its experimental verification wasn't a triumph. The Standard Model didn't have to be true!

The solar neutrino thing is phenomenal, at least to me, we surely see CKM mixing in the quark sector, but to see leptons change flavor, and do so on such a grand scale is astounding. When the problem first came up, flavor violation wasn't even on the table.

Precision cosmology has really laid out that there's something really, really big about Physics that we're missing. Really big. And it says it with such statistical and systematic vehemence that even the most curmudgeonly skeptic (myself included) is forced to confront it. In combination with the Bullet Cluster, there's almost no escape from the conclusion that there's something really important to be found.

Totally agreed that parameter space, without qualifiers, is a vague term.

Some parameter spaces are more important than others. I'd argue that the absence of new signals at LHC, the absence of bright new lines in Fermi/GLAST data, the absence of new lines in ultra-high energy cosmic rays, the absence of any signal in any EDM experiment, the absence of any equivalence principle violation or anything else in the gravitational sector, the absence of any experimental signal for any dark matter candidate, the continued expected behavior of the Hulse-Taylor pulsar, etc. are all important, especially in light of the problems of CP-violation, the complete incompatibility of the Standard Model with General Relativity, and the extremely good agreement between observed cosmology/BBN with the \LambdaCDM model.

A lot of really good people have pushed really hard experimentally on entirely reasonable theories, and those ideas have been severely constrained. In my own field, precision tests of gravity, theory is forced to contort itself to avoid experimental constraint. LHC is putting the screws to supersymmetry; there's still plenty of room there, but there's a lot less than there was a few years ago.

As experimentalists, we've got little patience for contrived models of parameter space. As each experiment takes 5-10 years, we only get a few in our lifetime, so we try to make our work as meaningfully-impactful as we can.

What are the assumptions behind "log plots of parametrized experimental progress"? What do these mean in the real world?

To give an example of why "pouring money into it and getting slower and slower progress" could translate into linear progress on a log plot, imagine you have to pour in x² amount of (money, people, time) to get to level x of progress.

In that case "we go slow" means, "we'll gobble up larger and larger amounts of money, but everytime people get impatient we'll have some bone to throw at them".

Add that to the fact there is no global dependency tree of "What we need to discover to make this practical technology possible", how can we be sure that existing/future research funds are focused in the areas needed to make the most valuable technologies available?

Is that why we're doing physics research? Practical technology?

Isn't it?

Understanding things is certainly great, but you can't even claim you understand something new if you can not use that new understanding to achieve something you couldn't before it.

Or, more clearly, pure theory is good for mathematicians, but scientists can not even claim a theory is new if it has no application.

Isn't it?

It's certainly not what I'm expecting. Even if it hadn't gone on to be central to our engineering, I would have liked to have known about general relativity or QCD.

Understanding things is certainly great, but you can't even claim you understand something new if you can not use that new understanding to achieve something you couldn't before it.

What do you mean by understand something new? This week we started to understand something new - understand many things new - about Pluto. Are you trying to claim that this isn't true unless we can use it somehow? What is it you're trying to say?

Or, more clearly, pure theory is good for mathematicians, but scientists can not even claim a theory is new if it has no application.

Is astronomy not a science? Or palaeontology? Or archaeology? Those are all observation-oriented sciences that don't conduct experiments but do gather information and develop knowledge.

I have no idea what it is you're trying to say about claim a theory is new - do you want to rephrase that? What would you say about the recent discover of pentaquarks? Pentaquarks are useless, but our knowledge of them is quite new.

At roughly constant inflation-adjusted budget, many experiments are getting factors of two in performance improvement today roughly as quickly as they were getting factors of two in the past.

The job market for physics has not changed substantially in the last twenty years.

By 'we go slow because we will go far', I meant only to emphasize that regular incremental improvements generally trump blitzkrieg efforts.

What's EDM?

electric dipole movement or maybe electronic dance music

http://www.int.washington.edu/talks/WorkShops/int_08_3/Peopl...

what is this \theta_{13} ?

The neutrino mixing angle Θ13 probably, written in latex :-)

Given your perspective, what do you make of stuff like Umbral Moonshine http://arxiv.org/abs/1204.2779 and ER=EPR http://arxiv.org/abs/1306.0533 ?

In both cases, I'd be out of my professional depth to make any definitive statements about either paper. My expertise is much closer to experiment.

Maldecena and Susskind are both well regarded and accomplished.