Another giant moves on. John Wheeler died yesterday. He’s known for bringing to light many wonderful pieces of physics (he’s also credited for coining the term “black hole”), classical and quantum (helping craft many of the ideas surrounding issues in quantum gravity, for example), and for being a great teacher. There’s an obituary* by Dennis Overbye in the New York Times here. I’ve borrowed their lovely photograph (which was given no photographer credit, so I cannot).
[Update: Daniel Holz has a personal reflection here.]
-cvj
*I learned of the article from Often in Error.
Did you catch the discussion on NPR’s Science Friday just past? I was particularly pleased to hear some calm, thoughtful responses from someone who definitely knows his way around the issue, on a major broadcast. What issue? Whether or not we high energy physicists are carefully endangering planet earth (or even the whole universe) by switching on the Large Hadron Collider (LHC) later this year (or whenever it is due to start collisions). You’ll recall the lawsuit, since I posted on it here (with links to other thoughts), and perhaps you even recall my April Fool post on the matter.
Well, Ira Flatow was talking to Frank Wilczek! It was a good, informed chat around the issues that also gave Frank a chance to explain a little about what the machine was really constructed for (since this seems to so easily fall out of these public discussions of black holes and extra dimensions and strangelets (interesting as they are), and to plug his book that is due to come out. Since it’ll almost certainly be a really interesting Continue reading ‘Frank Common Sense’
Takuya Okuda talking about Wilson Loops at the most recent SCSS, UCLA, Dec. 2007. Click to enlarge.
The next regional string meeting is a two-day one at Caltech, this Friday and Saturday, organized by Joseph Marsano. It’s going to be full of interesting talks and conversations, as usual. Please encourage your graduate students to come, especially, since special effort is made to make sure that each talk begins with a pedagogical portion to help non-experts in that subfield navigate and see the motivation.
The speakers are:
Continue reading ‘Southern California Strings Seminar’
Did you see the Nike commercial with Kobe Bryant as Einstein?
It is part of a series with the theme “genius” in which he plays a variety of historical figures with a reputation for innovation. More (including the video) on Bryant’s website, and there’s a breakdown by fliptomato on his blog (where I found this).
Given the opening line of fliptomato’s blog post, I wonder if he (or the commercial makers) knows about the excellent Gary Larson cartoon from very many years back Continue reading ‘Kobe as Einstein’
Tomorrow I’m shooting all day for a TV show that is going to focus on the idea of alternative universes (or parallel universes, if you prefer). Should be fun. The setting at least will be interesting (more on that later) and it ought to be interesting to see how the writer puts all the material together into a coherent narrative. Part of my job will be to try to emphasize that while parallel/alternative universes show up a lot in actual scientific discussions (and have done for a long time), we have not yet had anything like a good observational or experimental reason to believe in their existence anywhere other than in our imaginations. It’s vital to get this across (I hope they don’t just edit it out) because people are so willing to believe in many half-baked fanciful ideas - and this is one of them - and when they show up in a science documentary (this is (again) for the History Channel’s “The Universe” series, which has been very good) with actual scientists being quoted, one should be especially careful (as we were on the “Cosmic Holes” episode (with different filmmakers), which has proven to be rather popular, and is full of speculative ideas like travel using wormholes and time machines right alongside equally fantastic-sounding things, like black holes, which are in fact a scientific reality). The rest of my job will be to talk about some of the places where the idea shows up in modern thought, some of the reasons why, and some of the opportunities for solving various challenging problems (and maybe creating a host of others!!) can be afforded by such ideas.
All that aside, this reminds me of something else entirely - Do you ever have those days when you feel like you’ve accidentally stepped sideways into an alternative universe? I do. Recently, I had a huge dose of it. Sit back and I’ll tell you the story…
Continue reading ‘Consider the Alternatives’
The previous post was a farewell to black holes in the class, not here on the blog. (And it was not quite a farewell there either, since the midterm yesterday was all about the properties of the Reissner-Nordström black hole, representing a black hole with an electric charge, and a nice computation involving cosmic censorship.)
There have been two rather notable discoveries in the black hole astrophysics world this week. The first is the discovery of what seems to be another case of an intermediate mass black hole (there was only one example known before). Not the supermassive ones that live at the centers of galaxies (tens to hundreds of millions of times the mass of our sun), and not stellar mass ones of a few times the mass of our Continue reading ‘All Creatures Great and Small’
Yesterday here at USC was my last lecture in the class about black holes (see also here). We’ve got to move on to other topics (Cosmology, Einstein’s equations, etc) and so cannot do any more. It was a fun last lecture though. I pulled together a few scraps of things I did not finish in the previous lecture (such as the extraordinarily high percentage of binding energy per unit rest mass you can extract with rotating black hole orbits - just what you need to power things like quasars) and then finished with:
-
A taste of Hawking radiation, the Bekenstein-Hawking entropy and the wonderful and beautiful subject of black hole thermodynamics that opens up when you combine gravity with quantum mechanics*, followed by…
- A quick discussion of the Penrose process for extracting energy from rotating black holes. (I’m sure that all (past, present or future) super-advanced civilizations must be using them as the ultimate emissions-free means of generating energy for heating their homes and so forth. No, really.)
*Of course, all undergraduates commonly hate it when you dare bring in stuff from other classes, so to Continue reading ‘A Farewell to Black Holes’
[Update:- NB: This was an April Fool joke. -cvj]
Some breaking news for a change. I’ve only heard snippets of this and so I’ll update later with more as I get it. That silliness that was in the news about two physicists pursuing a lawsuit against the Large Hadron Collider has suddenly become serious. (Image right: the CMS detector at the LHC, taken by Valerio Mezzanotti - from a NYT article about the LHC last year.)
Recall that the issue was that there would be the possibility of the experiment creating mini black holes that could gobble up the earth and that the CERN scientists have not done enough to demonstrate that this was not a safety issue. Of course, and has already been said in several places (see e.g., Phil’s general level post about the physics and the case here), this is utterly ill-conceived and in any case certainly not the way to go about things, but it seems that the legal route can be quite damaging for science, in the right hands.
What seems to have happened is this. Since the suit was filed in Hawaii, it falls under US Federal jurisdiction, and has been taken up as an emergency issue before the Supreme Court. Somehow the litigants got a hearing on this with the help of powerful friends who have what can only be thought of as another example of the anti-science agenda we’ve a lot of in various branches of the government in recent years.
The upshot is that the Supreme Court has announced today that they are requiring all Continue reading ‘More Trouble for LHC?’
[Update:- NB: This was an April Fool joke. -cvj]
Well, I learned recently* that the BBC wildlife program makers have done it again, breaking new ground in scientific discovery while making a new series. Quite amazing this time. From the Daily Telegraph website:
The BBC will today screen remarkable footage of penguins flying as part of its new natural history series, Miracles of Evolution.
Also:
The programme is being presented by ex-Monty Python star Terry Jones, who said: “We’d been watching the penguins and filming them for days, without a hint of what was to come.
“But then the weather took a turn for the worse. It was quite amazing. Rather than getting together in a huddle to protect themselves from the cold, they did something quite unexpected, that no other penguins can do.”
Above right (click for larger view) is a screen shot that I took of the incredible footage Continue reading ‘Liberated Penguins’
A silly lawsuit vs the search for physical law, that is. What’s the story?* An attempt to stop the Large Hadron Collider (LHC) in Geneva from operating over fears that the experiment will destroy the earth by creating a black hole that will swallow it up. Or some other bogeyman. Article by Dennis Overbye here, or here, and there’s a Fox News story by Paul Wagenseil here.
The lawsuit, filed March 21 in Federal District Court, in Honolulu, seeks a temporary restraining order prohibiting CERN from proceeding with the accelerator until it has produced a safety report and an environmental assessment. It names the federal Department of Energy, the Fermi National Accelerator Laboratory, the National Science Foundation and CERN as defendants.
Quite an entertaining read can also be found at the two plaintiffs’ website. The main Continue reading ‘Law Vs Law’
We’ve been studying rotating black holes in my class this week, which has been fun. We get to apply the techniques we’ve been honing in the context of the Schwarzschild solution (link to recent posts below) to a bit more complicated solution, the Kerr solution, which includes rotation. Some equations follow, although you needn’t be put off by them. Most of this will make sense without really understanding them much. Just so you can see the shape of the things we scribble, I’ll show you the equation that captures this curved spacetime geometry, with no real explanation (sorry):
Here 
and 
The parameter 
is the ratio of the solution’s spin or angular momentum 
to its total mass 
, measured in appropriate units. It’s a very important solution to get to grips with, since it’s not just fantasy physics, but highly relevant for astrophysics since black holes that are “out there” are unlikely to be non-rotating, and in fact, one can expect them to be rotating at quite a clip in many cases. A good many black holes - including some of the Continue reading ‘Bigger than the FCC’
In physics, most of what we do is look for the simple, often in extremely complicated systems. If you’re asking the wrong question, or looking at the wrong aspect of the system, this quest for the simple is unlikely to work at all, but the right question asked about the right aspect can yield rather striking insights, often with far-reaching consequences. Although it often is not emphasized in this manner during our school or undergraduate (and sometimes even graduate) education, this is the primary skill in the physicist’s arsenal that we teach and learn. (See an earlier article here for a take on this.)
Sometimes, you don’t need the sharp eyes and years of training and drilling in these seemingly arcane (but, I’d argue, most natural) arts (and the requisite sequestering away in monasteries and nunneries with abstinence, self-flagellation, and so forth) - there are times when if just jumps out at you that there’s a simple question or two Continue reading ‘Sand, Man’
I got an email from one of the group’s graduate students today*, pointing to an archive of videos of lectures by the great Sidney Coleman. He’s doing quantum field theory. This makes this a marvelous resource, in principle, and so I thought I’d share them with you. They are here.
I wonder: are these the lectures that Jacques Distler has mentioned attending a few times in the past on his blog? This was the 1975-1976 year, a graduate course. I wonder if anyone (else) I know was in that class room…
[Update: I learned from the discussion over on Jonathan Shock's site that there are some partial lecture notes from the course here, by Bryan Gin-ge Chen, based on notes by Brian Hill. He's looking for help on completing the project, so get in touch if you want to help out.]
I’ve never seen Coleman in action before, and so I was immediately rather curious, Continue reading ‘Lighting Up Field Theory’
Am I the only one who sees this, or does this look like the head of some giant friendly robot, all smiles with big cheeks? Remember Brad Bird’s Iron Giant, for example?
Well, it is actually not from science fiction but science fact. And it is a robot, sort of - well it can be controlled remotely to swivel its head and so forth. It is actually a Continue reading ‘Biggest Binoculars Ever’
It’s a bit more than a month away. It’s always fun every year. It’s a Los Angeles celebration of the written word, done in wonderful sunshine, with hundreds of marvellous events in three days for young and old - Yes, it is the LA Times Festival of Books, coming up the weekend starting April 25th. The main daytime proceedings take place on the 26th and 27th (Saturday and Sunday) and I recommend them to you if you’ve not been. Mark your calendar. (Once you’re over there on Sunday, stay for the Categorically Not! event in the evening (entitled “Loops”), which will involve among others, science writer Dava Sobel!!) (Above right: One of the 2008 theme images from the Festival’s website. More here.)
The Friday evening will see the book prizes given out, kicking off the festival as usual. I remembered this just now because I found myself curious about the shortlist of books in the Science and Technology category. I wondered if there was something on Continue reading ‘Festival of Books’
Continuing a bit about the microbiology to be found in the garden, I did a post not so long ago on Correlations giving an update about the composting system I started a while ago (post on that here). You might find it interesting, and so I thought I’d let you know about it. It is here.
All’s looking well for an exciting Spring season of gardening!
-cvj
Wow, a lot of time has passed since I thought I’d get around to posting about this. You’ll recall that I went to take part in the taping of a segment for Comedy Central some time ago. Well, later on I went to the taping of the full show in which it will appear, and it was an amusing and interesting experience.
The show? Comedy Central, and in particular, Daily Show fans will be pleased to learn that Lewis Black finally has a show of his own, and it is called “The Root of All Evil”. The format is that he presides as a judge over a case examining which of two popular Continue reading ‘Tales From The Industry XIX - Black Comedy’
Black Holes, by Tamsin Van Essen. Part of a series of lovely ceramics with a physics theme. For more, visit the websites here and here.
As you may recall from the post I did some time ago, the “Light Cone” is a rather important concept in physics, and keeping track of it in a given physical scenario is an extremely important tool and technique for understanding many physical situations. (I urge you to review that post before continuing reading this one.)
One way to understand a most important concept - the event horizon - is by keeping track of lightcones, and so let’s go ahead and explore that here. The outcome is that Continue reading ‘Tipping the Light Cone: Black Holes’
Not quite as (juvenile) funny as the equivalent phrase when rings were discovered around the seventh planet, but it’ll do as a post title. I’ll tease you with the image here Continue reading ‘Rings Around Rhea’
The next Categorically Not! is on Sunday March 9th (upcoming). The Categorically Not! series of events that are held at the Santa Monica Art Studios, (with occasional exceptions). It’s a series - started and run by science writer K. C. Cole - of fun and informative conversations deliberately ignoring the traditional boundaries between art, science, humanities, and other subjects. I strongly encourage you to come to them if you’re in the area. Here is the website that describes past ones, and upcoming ones. See also the links at the end of the post for some announcements and descriptions (and even video) of previous events.
The theme this month is Puzzles! Here’s the description from K C Cole:
What isn’t a puzzle? The universe, life and everything are essentially puzzles that, to borrow from Einstein, “beckon like a liberation.” Designing buildings, choreographing dances, cooking meals and getting along with other people all involve solving puzzles (as, of course, does figuring out what’s right in front of your eyes—not to mention putting together a program such as Categorically Not!) A love of puzzles and the challenge of solving them is deeply embedded in human nature.
Gwen Roberts, Scott Kim, Gavin Scott.
Our March 9th Categorically Not! features puzzlemaster Scott Kim, who’s Continue reading ‘Categorically Not! - Puzzles!’
I don’t mean that in a bad way. It is what it is. Quite varied and wonderful, our universe is, with unexpected features I don’t think many would have guessed at not long ago (like the fact that we only understand what about 4% of it is!! Crazy, in a Continue reading ‘Still Crazy After All These Years’
Planetary Nebula NGC 2371. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
A lovely release from the Hubble Heritage project. Well worth clicking on for more detail. The image was made using Hubble. It’s a planetary nebula (NGC 2371), the Continue reading ‘Warm and Fuzzy’
Not long ago David Morrison (UCSB) came to the mathematics department here at USC to give a colloquium.
This was a treat for me for many reasons. Here are three:
- It’s always good to see Dave. He’s one of the people I’ve known in the field was since my very first postdoc when I was learning to survive in the big bad world on my own after graduate school. I mostly could not understand a word he or anyone there else said in those days (IAS Princeton, right in the belly of the Continue reading ‘Beyond Einstein: Fixing Singularities in Spacetime’
I had some unusual guests in my General Relativity lecture yesterday, Eric Salat and Philip Shane, two film makers from Left/Right productions. They’re working on a documentary for the History Channel on the development of various ideas in physics in the early 20th Century, and they wanted to know more about the topics, and to see a full (1 hour and 50 minute) lecture from me.
While it is the History Channel (hence the dramatic subtitle - sorry), it is not part of the series “The Universe”, by the way. It is another separate part of the increased very welcome expansion of that channel’s science programming. Have you noticed the diversification of their programming that they’ve been doing? I’ve mentioned it before, and a number of people have commented on it to me elsewhere. It has been great to see.
It’s always fun to have more people in the classroom, and so we had a lot of fun… (Or at least, I did…I hope everyone else did too.) I happened to be doing a lecture on Continue reading ‘Tales From The Industry XVIII - History Looked On’
There was a sweet, sweet moment during the afternoon Cosmology, Gravity, and Relativity session on Friday. (See here.) I don’t think I’ll be able to convey its full intensity to you, but I cannot let it go unmarked. The background comes from a personal place. In addition to my being, for many years, somewhat of a relative anomaly in being a black theoretical (high energy) physicist, there’s another component to that rare situation. My parentage is West Indian (or “Caribbean”, I might say, since in my experience the other term often does not register with many people from the USA), and until recently, I’ve not really known (m)any other such people in theoretical physics*. What struck me on Friday was a single syllable.
Chanda Prescod-Weinstein (left), a graduate student at Waterloo/Perimeter, who has commented on this blog from time to time, and who I met for the first time on Thursday, was giving an excellent overview of her project to begin research on Doubly Special Relativity. Some of the motivating remarks involved simultaneously taking Newton’s constant, 
and Planck’s constant 
to zero (the idea is that quantum gravity’s Planck length might remain finite in this limit, and thus remain in the physics as a new scale that breaks Lorentz invariance at Continue reading ‘Haitch’
I find myself in Washington DC for two and a half days, attending an interesting conference. It’s the annual meeting of the National Society of Black Physicists* (NSBP), and I’ve been invited to give a talk (which I gave a few hours ago, entitled “The Dynamics of Flavour in Gauge/Gravity duals”, with a focus on what we can learn about experiments and observations of strongly interacting nuclear systems using string theory. Post about that here). I’m here for more just the talk, however. I also want to talk - in the sense of converse. Basically, it is of interest to me to get a feeling for what’s going on with the issues of underrepresented minorities (in this case, people of African descent) in Physics. As you know, the numbers are vanishingly small, and as you also know from reading my writings, I am very interested in this issue, and of course, how to make it not an issue, by helping more people find their way into the field and have as much opportunity to do well as the next person.
(Scene from the opening banquet on Thursday night. The featured speaker (no, not on stage in photo) was 2006 Physics Nobel Laureate, John C. Mather. Click for larger.)
It has been years since I came to one of these, and I must say it is a real pleasure to be here. There seems to be a lot of contrast to how I remember things from the Continue reading ‘DC Crossover’
There’s a total eclipse of the moon tonight (Wednesday 20th)! NASA has a nice website on the timings, and some background information. Totality is at about 10:26pm EST, (see the NASA graphic to the right (click for larger)) but you should start watching before that to see the changes, which are always lovely to see. Naked eye is good, but if you have a pair of binoculars to help - even better!
Locally, if you’re interested you can join some of the Astronomy 100 students and TAs Continue reading ‘Total Eclipse of the Moon’
I’m pleased to introduce a guest blogger today. It’s Nick Halmagyi, who you might have seen comment here from time to time. Nick is a postdoctoral researcher in Theoretical Physics, currently at the Enrico Fermi Institute in Chicago. Before that, he was a graduate student in our High Energy Physics group at USC, which is where I met him. Nick wrote his reflections below for Seed, and he reproduces a version of it (with permission - see details below*) here. I hope you enjoy it.
-cvj
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Theoretical physics is a tough subject. Just one example of how hard things can get is when you ramp up the energy density of a system, the physics used to describe the system itself starts to change. At first it may be a small tweak in the parameters that appear in the equations (the electric charge for example), but then there can be large, abrupt transitions.
The biggest system we study is the universe, and immediately after the big bang all of its energy occupied a tiny region of space. Back then, the energy density was enormous, and as the universe grew over time it underwent several transitions before it became what we now observe.
I’m a theoretical physicist, in part, because I relish the challenge of studying the entire Continue reading ‘Nick Halmagyi: Why I do Science’
Neil deGrasse Tyson helped Stephen Colbert with his training to be an Astrophysicist recently. Neil’s advice is excellent of course, urging (for example) questioning and open-mindedness. You can learn from the clip below about Colbert’s take on this advice.
Among the many great exchanges:
Continue reading ‘Simple Steps to Becoming an Astrophysicist’
A commenter asked how the aforementioned movie viewing and panel discussion went on Friday (movie: Jumper), and so I thought expand a bit on the answer I gave:
___________________________________________________________________________________
It went very well. We were at the School of Cinematic Arts, at USC. We had a full house in the Norris Theatre, which was great to see. Most of the audience was students from the SCA, I think, with some of the faculty present, and people from the film’s parent studio, and several others. For the panel, present were two of the film’s producers, the visual effects supervisor, costume supervisor, production designer… basically, the perfect people to have a discussion with about the physics! I won’t try to list all names since I did not catch all of them and don’t want to mis-credit people for being there who weren’t.
Teleportation physics aside for a moment, I’m very impressed with how they realized Continue reading ‘Tales From the Industry XVII: Jump Thoughts’
No, not spoiler in that sense. Doug Liman’s new action movie “Jumper” is all about teleportation, you see, and one of the questions that’s going to be on people’s minds is something like “Is teleportation really possible, or is it just some silly science fiction thing?”. I like it when such questions come up, and I like trying to answer them too.
This time I get to do it officially, since Doug Liman’s people are doing a private screening of the film this evening and there’ll be a panel of some of the film’s creators and a scientist for questions and answers afterward. I’ll be the scientist.
The downside is that I’ll be the bad guy of the evening by having to pour a bit of cold water on some of the flights of fancy. The spoiler, you see, as in spoilsport. The upside (besides, you know, free movie) is that I’ll maybe get to explain some really Continue reading ‘Movie Spoiler?’
So the Onion’s gone and mixed some astrophysics with basketball. Headline:
“Shaq Terrified Of Phoenix Suns After Reading About Supernovas”
(Image on right also from the Onion.)
You can tell how it’s going to go from the title, although it’s rather amusing just how much stellar astrophysics they pour into the article (not even trying to disguise it much). Extract:
…new Phoenix Suns center Shaquille O’Neal admitted Monday that, upon reading about the phenomenon of massive stellar explosions popularly known as supernovas, he is now terrified of the entire organization.
(Wow… Shaq isn’t in LA any more? Huh. I’m so out of it. Update: Oh, yeah, I remember now. He went to Miami in 2004. Evidently I don’t follow the NBA.)
…and further:
Continue reading ‘Stellar Basketball Physics’
A match made in the heavens? (sorry….couldn’t resist…)
Continue reading ‘While Reading the Physics Personals…’
Well, only four weeks and change behind us in this course, and… the class (see here and here) is ready to understand this wonderful equation:
and all that it implies. What is it? It encodes the shape of spacetime around a spherical blob of mass of total mass M. No, don’t worry too much about the details, since this is not a lecture about General Relativity….. it is just nice (I hope) every now and again to get a look at the sorts of things we use in our day to day work. This “warped” spacetime encodes what we interpret as the gravitational field (in the old Newtonian language) due to a spherical (or, to a good approximation, almost spherical) mass. Like the sun, or the earth, or that tennis ball in the corner there*. It is an exact solution Continue reading ‘Mass Matters’
My first time sitting down to watch this show in a while and, bizarrely enough, there’s a colleague on the telly! Well, I think that perhaps Lisa was trying a little bit too hard in one or two places to get the physics out. On Colbert, I think you just have to go with the flow and the comedy! But she got quite a bit out in the short time she had…
My favourite bit:
Randall: “Like…the fact that Einstein has taught us that spacetime can be curved or warped…”
Colbert: “Don’t patronize me, I know that…”
Continue reading ‘Randall on Colbert’
So Chris and Sheril have announced the next step in the journey to a real debate about science issues of note that intersect with the current political sphere. And they’ve come a long way in a short time! Here’s some of what they said in a recent post:
ScienceDebate2008 is now co-sponsored by the American Association for the Advancement of Science, the National Academies, and the Council on Competitiveness. We were looking at venues, and finally settled on an offer from the Philadelphia-based Franklin Institute–named, of course, after one of this country’s first and greatest scientists. We can’t think of a more appropriate venue.
And guess what?! They’ve actually invited the candidates: Hillary Clinton, Mike Huckabee, John McCain, and Barack Obama.
So the next step is to get the event (they suggest April 18, 2008) taken seriously by Continue reading ‘Science Debate 2008 - Closer to Reality’
Well, Tuesday was a big day in class. We reached a landmark - the introduction of one of my very favourite thoughts of the 20th Century: the Equivalence Principle. This is the realization of Einstein’s that there’s something profoundly odd about Newtonian mechanics and Newtonian gravity that hints at something deeper.
Quick reminder from high school (just two formulae, please bear with me): You know Continue reading ‘Equivalence’
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