Tuesday, February 2, 2016

Getting physical (again)

I haven't posted physics news for weeks, and there is much to catch up on. This should give us a good start.

Now with hidden dimensions!
A battle is underway for the soul of physics. That battle rages over the proper balance and relationship between theory and experiment, and the extent to which the subjective beauty of the mathematics underpinning any particular theory matters.

Me? I'm all for bold theorizing -- it offers great grist for the SF-authorial mill -- but when wearing my physicist hat, I'm troubled when a theory, such as string theory (the umbrella term, as it happens, for many theories, not just one), not only hasn't been confirmed experimentally, but offers no hope, even (ahem) theoretically, for testability. For a longer discussion, see "Data vs Theory: The Mathematical Battle for the Soul of Physics."

Now we can all calm down :-)
A longstanding riddle about our understanding of the Universe -- aka, Big Bang theory -- involves the relative abundances of specific elements from the periodic table. In particular, the observed prevalence of lithium is simply way below Big Bang predictions. So is our overarching cosmological theory wrong?

Perhaps not. A recent study concludes all that lithium was produced and still exists, but much of it has disappeared down the maw of stars. Cool (or, er, hot) stuff. See one of Astronomy Magazine's top-ten stories of 2015:  "Solving the lithium mystery."

Speaking of the elements, "Periodic table's seventh row finally filled as four new elements are added." But while the new elements likely will make it to wall charts in high-school chemistry classes, the elements themselves won't be in chem labs. These elements all decay within a fraction of a second. That's faster than even Tom Lehrer can sing the periodic table  :-)

(Personal note: my undergrad physics adviser was Tom Lehrer's first sound engineer, back when both were at MIT.)

Only much much smaller
I have long been interested in the potential -- and the difficulties -- of achieving atomically precise manufacturing (a better phrase than nanotech, a term which has been hyped beyond recognition). The catch always seemed to be picking up and moving individual atoms -- apart from the noble gases, atoms have, fortunately for us complex organisms, a tendency to chemically bond...

It looks like researchers have come a big, er, a tiny, step closer. See "Molecular arm grabs, transports, releases molecular cargo." A key quote from that article:

UK chemists have devised a nanoscale robot that can grasp a cargo molecule, pick it up, place it in a new position some distance away and release it. At no time does the cargo dissociate from the machine or exchange with other molecules. While such a sequence of actions is trivial on a macroscopic scale, to achieve it synthetically with small molecules is unprecedented and could mark the start of a new era of molecular robotics. Multiple similar robots in sequence could, for example, replicate a factory’s assembly line to build increasingly complex molecular structures.

I'd argue we've already covered a great deal, ranging from the cosmic to the nanoscale, and from the most theoretical to hands-on. (Theoretically hands on. Those transuranic elements are highly radioactive.) But if you're hungering for more, check out Physics World's highlights and predictions for the year: "The world of physics in 2016."


Keith Kenny said...

I share your concern about ideas like 'string theory' killing inquiry. If we'd stuck with earlier well accepted ideas where would be be? Perfecting an algorithm for how many turtles supported the Earth? Pondering whether additional crystalline spheres might hold objects beyond our telescopes? My least favorite misused word is 'evolution', i.e., using it for any change—wood in my fireplace evolved into ashes this morning.

Thanks for the note on ATM (vs nanotech) reaching a milestone. I'm sure if such small devices in sufficient numbers could make a manufacturing plant, they wouldn't need to. Who needs a factory when invisibly small machines can make what is needed?

Edward M. Lerner said...

ATM? I'm guessing that's a typo for APM (atomically precise manufacturing).

Keith Kenny said...

Pardon my typo ... I meant to write APM.

Edward M. Lerner said...

Typos happen :-)