Physics
esiegel | December 17, 2011"Everything that slows us down and forces patience, everything that sets us back into the slow circles of nature, is a help." -May Sarton
It's unbelievable how much more amazing the world becomes in slow-motion. You've probably seen some high speed cameras that shoot at astounding frame rates, such as the video (below) of a popping water balloon, at literally ten thousand frames-per-second.
Video credit: Youtube user Nathan Gray IX.
Compared to normal television or film, where frame-rates are typically only 24 to 30 frames-per-second, it's no wonder that this appears spectacular to our eyes…
drorzel | December 16, 2011Physics World has released its list of the top ten breakthroughs in physics for the year, and it doesn't include either fast neutrinos or the Higgs boson:
The two physics stories that dominated the news in 2011 were questions rather than solid scientific results, namely "Do neutrinos travel faster than light?" and "Has the Higgs boson been found?". However, there have also been some fantastic bona fide research discoveries over the last 12 months, which made it difficult to decide on the Physics World 2011 Breakthrough of the Year.
But after much debate among the Physics World editorial team…
drorzel | December 15, 2011Moving along through our countdown to Newton's birthday, we have an equation that combines two other titans of British science:
This is the third of Maxwell's equations (named after the great Scottish physicist James Clerk Maxwell), but it originates with Michael Faraday, one of the greatest experimentalists of the day. Faraday was a fascinating guy, who came from humble origins-- he was an apprentice bookbinder who managed to get a job as Humphrey Davey's assistant-- to become hugely influential in both chemistry and physics. He also played an important role in science communication and…
drorzel | December 14, 2011As we march on toward Newton's birthday, we come to the second of Maxwell's famous equations, which is Gauss's Law applied to magnetic fields:
For once, this is pretty much as simple as it looks. The divergence of the magnetic field is zero, full stop. As I said yesterday (albeit using the wrong terminology), the left-hand side of this equation basically means that you look at the magnetic field in the vicinity of some point in space, and ask how many little arrows point toward the point of interest versus how many point away. What this equation tells us is that no matter where you look,…
drorzel | December 14, 2011Over at Scientific American, John Horgan has a blog post titled In Physics, Telling Cranks from Experts Ain't Easy, which opens with an anecdote any scientist will recognize:
A couple of decades ago, I made the mistake of faxing an ironic response to what I thought was an ironic faxed letter. The writer--let's call him Tachyon Tad--had "discovered" a new physics, one that allowed for faster-than-light travel. In my reply, I told Tad that if he built a warp-drive spaceship, I'd love to hitch a ride. Dumb joke. For months, my fax machine churned out sheets covered with Tad's dense elaborations…
drorzel | December 13, 2011I was planning to let today's Higgs press conference pass with only a few oblique mentions in posts about other things, but apparently, I would lose my license to blog about physics if I did that. You'd think that, being married to a lawyer, and all, I'd know to read the fine print in these things...
Anyway, I don't really have anything useful to say about it. My very-much-an-outsider reading of this is that the evidence they see is suggestive, but somewhat less impressive than even the many attempts to lower expectations on Twitter and elsewhere suggested. It's probably there, but they're…
esiegel | December 13, 2011"There are no physicists in the hottest parts of hell, because the existence of a 'hottest part' implies a temperature difference, and any marginally competent physicist would immediately use this to run a heat engine and make some other part of hell comfortably cool." -Richard Davisson
The Large Hadron Collider is the most powerful particle accelerator in the world, capable of accelerating protons absurdly close to the speed of light: 99.9999991% of the way there! Within a 26-kilometer-long ring, largest in the world, protons are accelerated both clockwise and counterclockwise up to these…
kmcwalsh | December 13, 2011This guest post was written by Brookhaven Lab physicist Kostas Nikolopoulos.
Today's public seminar at CERN, where the ATLAS and CMS collaborations presented the preliminary results of their searches for the Standard Model (SM) Higgs boson with the full dataset collected during 2011, is a landmark for high-energy physics!
The Higgs boson is a still-hypothetical particle postulated in the mid-1960s to complete what is considered the SM of particle interactions. Its role within the SM is to provide other particles with mass. Specifically, the mass of elementary particles is the result of their…
drorzel | December 13, 2011And what happened then?
Well, in Who-ville they say
That the Grinch's small heart
Grew three sizes that day.
And then the true meaning
Of Christmas came through
And the Grinch found the strength
Of ten Grinches, plus two
-- Dr. Seuss's How the Grinch Stole Christmas
It's nearly Christmas, so SteelyKid keeps demanding to watch the two classic Christmas specials we have recorded, Dr. Seuss's How the Grinch Stole Christmas and Rudolph the Red-Nosed Reindeer. Watching these over and over again, my thoughts naturally turn to physics, and what sort of physics you could do with these shows.
The…
drorzel | December 13, 2011As the advent calendar moves into the E&M portion of the season, there are a number of possible ways to approach this. I could go with fairly specific formulae for various aspects, but that would take a while and might close out some other areas of physics. In the end, all of classical E&M comes down to four equations, known as Maxwell's equations (though other people came up with most of them), so we'll do it that way, starting with this one:
This is the first of Maxwell's equations, written in differential form, and this relates the electric field E to the density of charge in…
drorzel | December 12, 2011Having covered most of what you need to know about classical physics, the traditional next step is to talk about electricity and magnetism, colloquially known as "E&M," though really, "E and B" would be more appropriate, as the fundamental quantities discussed are the electric field (symbol: E) and the magnetic field (symbol: B), whose effect is given by today's equation:
This is the "Lorentz force law," giving the force experienced by a particle with charge q moving at a velocity v through a region with both electric and magnetic fields. This is, in some sense, what defines those…
drorzel | December 12, 2011We kicked off our countdown to Newton's birthday with his equations of motion, so it seems fitting to close out the section on classical mechanics with another of Newton's equations, this time the Law of Universal Gravitation:
Like all the other equations to this point, I'm cribbing this from the formula sheet for my just-completed intro mechanics class, which means it's in the notation used by Matter and Interactions. This is sub-optimal in some ways-- I prefer to have subscripts on the r to remind you which way it points, but I don't care enough to re-do the equation.
So, this is the…
drorzel | December 10, 2011Today's advent calendar post was delayed by severe online retail issues last night and child care today, but I didn't want to let the day pass completely without physics, so here's the next equation in our countdown to Newton's birthday:
This is the final piece of the story of angular momentum, the undefined symbol from the right-hand side of the angular momentum principle: torque is defined as the cross-product between the radius vector pointing out from the axis of rotation to the point where the force is applied, and the vector force that acts at that point. As with the definition of…
drorzel | December 9, 2011Three quick items relating to science in book form:
1) It's that time of year again when every media outlet of any consequence puts out a "Year's Best {Noun}" list, and John Dupuis is checking the lists for science books so you don't have to. It looks like a pretty reasonable year for science in the best non-fiction-book-list world, but you can see for yourself.
2) In the "good books about science coming next year" category, the line-up for The Open Laboratory anthology of outstanding science blogging has been announced. I'm very pleased to report that my write-up of the OPERA preprint was…
drorzel | December 9, 2011Now that we've defined angular momentum, the next equation on our countdown to Newton's birthday tells us what to do with it:
This is the Angular Momentum Principle, and as with energy and momentum before it, this relates the time derivative of the angular momentum (that is, how quickly it's changing its value) to a quantity related to the interactions with other objects, in this case the torque.
So, why is this important?
As with energy, with the proper choice of system, we can often ensure that there is no net external torque on the system, in which case the right-hand side of this…
drorzel | December 8, 2011One of the things that is sometimes very frustrating (to me, at least) about popular physics books is that they rush very quickly through the physics that we already know, in order to spend time talking about wildly speculative ideas. This not only gives some of these books a very short shelf life, as their wilder speculations get ruled out, but it does a dis-service to science. Because as cool as some of the things that might be true are, the stuff that we already know is pretty awesome in its own right, and even more amazing for being true.
Happily, Frank Close's new book, The Infinity…
drorzel | December 8, 2011Moving along through our countdown to Newton's birthday, we come to the next important physical quantity, angular momentum. For some obscure reason, this gets the symbol L, and the angular momentum for a single particle about some point A is given by:
This is probably the most deceptive equation we'll see this season. Yesterday's definition of work clearly showed its vector calculus roots, but to the untrained eye, this just looks like a simple multiplication: You take the momentum (p) and multiply by the distance (r) from point A, and you're all set.
To those with a little mathematical…
esiegel | December 7, 2011"Alas! must it ever be so?
Do we stand in our own light, wherever we go,
And fight our own shadows forever?" -Edward Bulwer-Lytton
Ever since it was conjectured that the speed of light was the ultimate speed limit of the Universe, we have tried -- with the most powerful of our tools -- to push as close to it as possible.
Image credit: Sven Geier, retrieved from Alpha Centauri.
And we know the speed of light in vacuum -- in perfectly, completely empty space -- exactly: 299,792,458 meters-per-second. That's what we refer to as c, or more casually, the speed of light. And that's really exact,…
drorzel | December 7, 2011Following the basic pattern established at the start of our seasonal countdown to Newton's birthday, today's equation defines a piece that was left hanging in yesterday's post:
This is the technical definition of "work" in physics terms. It's also probably the scariest-looking equation to this point, as it explicitly involves vector calculus-- there's an integral sign, and a dot product. The basic concept is simple enough, though: you look at the force F exerted on an object, multiply it by the distance dr that the object moves under the influence of that force, and then add up the Fdr…
drorzel | December 6, 2011It's hard to go more than a couple of days without seeing another "imminent death of publishing" article somewhere, predicting the ultimate triumph of ebooks, There's one category of books that I expect to remain safe for the foreseeable future, though, namely books that are specifically constructed to be aesthetically pleasing. In other words, coffee-table books.
Clifford Pickover's new Physics Book is one of these. It's a very attractive and well-made book, pairing some 250 full-page images representing milestones in physics, paired with one-page descriptions of the underlying scientific…