If a black hole “sucked in” only photons, would it increase in mass?

Photons “die” when they interact with something, but if they do die, then what are they interacting with in the black hole?

These are two great questions, and I had fun coming up with answers to them. I gave a short answer, but any good physics question brings up a lot of related ideas, so I also put a longer answer that brings up some other ideas.

Short answer:
Yes. Einstein taught us that energy and mass are two aspects of the same thing. Even though the photons are massless on their own, their energy can increase the mass of the black hole when they are absorbed. The event horizon prevents any information from escaping a black hole, so we can’t know exactly what the photon interacts with.

Longer answer:
When a photon is absorbed by regular matter (anything you see around you), its energy is absorbed by by one of the particles in that object. For example, an electron absorbs the photon, and moves to a higher energy state within the atom. The key thing to remember is that there are billions and billions of different ways the photon can be absorbed by regular matter.

Black holes are much simpler. They have only 3 things that we can know about them: their mass, their electric charge, and how fast they are rotating. Physicists say that black holes have “no hair” to say that there are no other details that we can know about them.
So if we are sitting outside a black hole, and a photon falls past the horizon of the black hole, we can see how much it increased the mass or rotation of the black hole. Either way, the energy of the photon has now been added to the energy of the black hole. (See note below)

Now, why can’t we know what happens to the photon once it’s inside the black hole? Anything inside the event horizon can never come back out — that’s why we call them black holes. So we can’t do an experiment to see what happens, because we’d never see the results! Another problem is that the photon’s behavior is explained by quantum mechanics, and the black hole is explained by general relativity. No one knows how to make these two theories work together, so we can’t make a prediction that would involve both theories. String theory is one idea to solve problems like these, but it doesn’t work yet.

Note:

An outside observer can’t actually “watch” anything pass the horizon of the black hole. The outside observer will perceive the infalling matter as infinitely red-shifted, and taking an infinite amount of time to reach the horizon.  However, the object falling into the black hole will cross the horizon in a finite amount of its “own” time.

Now, a question of my own, for anyone who knows more GR than I do: does this mean that an outside observer will never be able to observe a mass increase for the black hole?

“Nerds like us are allowed to be unironically enthusiastic about stuff. We don’t have to be like, ‘Oh yeah that purse is okay’ or like, ‘Yeah, I like that band’s early stuff.’ Nerds are allowed to love stuff, like jump-up-and-down-in-the-chair-can’t-control-yourself-love it. When people call people nerds, mostly what they are saying is, ‘You like stuff’, which is just not a good insult at all, like ‘You are too enthusiastic about the miracle of human consciousness’.”

“Saying ‘I notice you’re a nerd’ is like saying, ‘Hey, I notice that you’d rather be intelligent than be stupid, that you’d rather be thoughtful than be vapid, that you believe that there are things that matter more than the arrest record of Lindsay Lohan. Why is that?’ In fact, it seems to me that most contemporary insults are pretty lame. Even ‘lame’ is kind of lame. Saying ‘You’re lame’ is like saying ‘You walk with a limp.’ Yeah, whatever, so does 50 Cent, and he’s done all right for himself.”

- John Green

(via stackmack)

We’d all be better off if we all just admitted that we’re nerds about something. Stop chasing this nebulous idea of The Cool and just like the stuff that we like and do what we want to do unapologetically.

The House of Representatives has already passed their version of the bill, but the budget battle is far from over.  Click here to write to your legislators to oppose the passage of such huge cuts to American science.

See this post at Cosmic Variance for more on this issue.

The appropriate response if you want to hurt BP, or, more importantly, try to prevent further environmental damage, is not to look for the most moral oil company.  Instead, take BP at their word, and move Beyond Petroleum.

How to do so? I’ve written about this before, here and here.

Maybe you’re not in a position to make a dramatic lifestyle change like going car-free.  But with a little planning, it’s not too hard to replace several car trips per week with bus or bike trips.  And if you’re lucky enough to live in Minneapolis, you have a new option to make bike riding even easier: Nice Ride Minnesota, a new bike-sharing program.

Based on the Bixi model, recently implemented in Montreal, the system allows users to pay a small subscription fee ($5/24 hours, $30/month, $60/year), and then take one of the 700 neon green bikes out for a spin, returning it to one of 60+ docking stations at the end of the trip.  The first half hour is no additional charge, so it encourages short trips, although the density of the stations in the covered areas makes it easy to hopscotch across town.  The system currently covers downtown and surrounding areas, including the University and uptown neighborhoods, and there are plans to expand.

Some have been dubious of how popular the system could be, but I have seen many of the bikes daily since the program was launched less than a month ago.  In fact, over 10,000 rides were taken during the first 20 days of the program.  This is encouraging news, not just for the success of this program and others like it, but also for encouraging bicycling as a common mode of transportation, not just recreation.

If you’re in Minneapolis, I encourage you to try it out! It’s a small investment of time and money to see just how bike-able the city is.  It’s an easy and enjoyable way to travel, and helps you feel more connected to the neighborhood than just driving through, windows up, with the radio on.  (Not to mention the health and environmental benefits.) After trying it out, you may find it worth your while to invest in a longer-term subscription and make Nice Ride part of your regular commuting and recreation plans.

Minneapolis was recently named the #1 bicycling city in the country, and with bike sharing and dozens of miles of new bike lanes and trails in the works, it can only get better.  I look forward to the day when people don’t act surprised that I ride my bike 3-4 miles to get somewhere, but see it as just another way of getting around.

I can’t forget to mention safety.  Bikes are considered equivalent with cars, and are meant to be ridden on the road.  This is not as dangerous as it sounds, especially on roads with bike lanes.  (Google maps now has a bicycling feature, that shows the bike trails and lanes.)  Just assert your right to your place on the road, travel in straight, predictable lines, and signal your turns with hand signals.  And please don’t run the stop signs and red lights.  It’s dangerous, plus it diminishes the respect that car drivers have for bicyclists, which is an important part of this movement.  It’s generally more dangerous to ride on the sidewalk, because it’s harder for drivers to see you when they make their turns, but it is legal in Minneapolis as long as the street is at least 50% residential.

Other cities with bike sharing:

• Paris, where Velib is probably the most successful example anywhere
• Ottawa, pilot program in 2009, to be expanded
• Melbourne, started this year
• Denver, Bcycle
• Boston, coming later this year
• Washington, D.C. / Arlington, VA; coming later this year
• Toronto, coming 2011

Please share your bike-sharing or bike commuting stories in the comments.  Also, let me know if I’ve missed any cities with bike sharing programs.

It becomes more difficult finding articles for a particular area of interest, as the arXiv feed for the limited area of high energy phenomenology dumps 20+ articles into my RSS reader every evening. This is not entirely unmanageable, as I mostly scan abstracts for anything related to my current work, and ignore the rest.  Plus, it is 2010, and a search function can turn up a paper on any topic I desire.  However, the number of articles makes it more difficult to keep abreast of more subfields, and tangentially-related, though helpful, articles in other fields go unnoticed.  Cross-pollination of ideas has been essential throughout the history of science, but it is more difficult in this era of increased specialization.  The increased number of papers in all areas can’t be helping matters.

The “arms race” aspect of publishing puts pressure on researchers, particularly young ones, to publish X papers in Y years to get a good postdoc, a tenure-track position, and finally to receive tenure.  Apart from the occupational stress involved, the production of papers as “least publishable units” may make the arc of one’s research more difficult to follow.  In addition, publication should ideally be more than just a resume-builder; it’s supposed to be an important part of the quest for knowledge.  I’m sure “publish or perish” has made more than one scientific idealist into a cynical resume-padder.

Other problems with the sheer number of papers include the reviewing load for professors (wouldn’t know) and the environmental impact of all those paper copies of journals (which shouldn’t be necessary in the internet age).  But the authors go further, saying that the reason for the profusion of articles is that there are too many bad papers getting published.  If there were some way to reduce the number of bad papers, they claim, the above problems will be alleviated.

But what does it mean for a paper to be worthless? Are there papers that are really worth so little that they shouldn’t even be published? I will explore this question in a post coming later this week.

The first book that I read was David Shenk’s The Genius in All of Us, whose thesis is that the usual conception of talent is incorrect.  Rather than being innate, talents are developed over years of sustained practice. (The canonical 10,000 hours of practice to become an expert, popularized by Malcolm Gladwell’s Outliers.)

The book, which is shorter than it looks due to the notes that fill about half of the volume, covers a variety of interesting topics to help debunk the notion that talents and other personal qualities are inborn.  The author describes a new understanding of genetics by throwing out the classic “nature vs. nurture” distinction, and arguing that the two are inextricably linked through the interaction of genes with their environment.  He goes too far with this in the final chapter, discussing the impact of epigenetic material (stuff other than DNA) on gene expression.  While there seems to be some credible and recent research on the effects of lifestyle on heredity, his assertion that “we may well be able to improve the conditions for our grandchildren by putting our young children through intellectual calisthenics now” seems to me to be a gross overstatement of the research.  Although much of the rest of the book is couched in this genetic argument, it isn’t dependent on his perhaps flawed understanding of the biology.

To determine the true sources of talent, Shenk discusses everything from the history of intelligence testing and “gifted” designations to the reasons for the athletic dominance of certain ethnic groups in their chosen sport.  (It is interesting to note that people used to wonder what genetic gifts allowed Jewish players to dominate basketball in the 30s and 40s, in much the same way that people discuss black players today.)  However, it seems that the most important factor for the development of talent is still the same: deliberate practice.

Deliberate practice requires more than just hard work, and it is not achieved by simply “putting in your 10,000 hours,” although both hard work and large amounts of time are certainly required.  Instead, it involves pushing beyond one’s current skill level to the point of failure, then picking up the pieces and trying again.  This type of practice is not necessarily enjoyable, but pushing beyond current limits is the only way to improve.  The practice activities have to be focused on particular aspects of the performance, with appropriate refinement and feedback for improvement.

It’s easy to imagine this deliberate practice as applied by a musician: seeking out more challenging pieces of music to play, focusing on the most technical measures, playing them repeatedly in solo practice, and later for a demanding instructor.  Or we can imagine the chess student, poring over volumes of opening and closing strategies, learning the tricks of the masters through solo study of their games, before testing those skills against ever tougher competition.

And of course, we can see this playing out with athletes, as it did in the other book I read to start my summer: Chris Ballard’s The Art of a Beautiful Game, which has chapters that discuss several of the basic components of basketball.  Though the book is wonderfully written, and a great read for any basketball fan, I couldn’t help but notice a strange battle playing out between the belief in natural athletic talent with the evidence of his descriptions of the players’ relentless practice habits.

This is most evident in the chapter on shooting, where Ballard repeats the old adage that “great shooters are born, not made.” He begins to contradict this almost immediately, by describing the exploits of a young Reggie Miller, who spent his days mastering shots from every spot on the concrete court in his backyard, begging his father to extend it, and then shooting from behind his mother’s rose bushes.  Or take Ray Allen, who “follows an unvarying routine to hone his stroke,” and keeping his physical fitness meticulously calibrated, to keep his form entirely replicable.  Both of these regimens sound suspiciously familiar after reading about deliberate practice.

Another example is given in Kobe Bryant, who is described as a “neurological freak” who has “a different hormonal and neurological makeup than the rest of us.”  But then we read how Kobe refined his game.  As a child growing up in Italy, he repeatedly watched NBA game tapes to the point that he had memorized all the plays, learning the right decisions in each situation.  If a teammate beat him with a move in practice, he would force that player to stay after, showing him the move repeatedly until he not only learned how to guard it, but was able to add it to his own game.  Knowing this level of dedication to the perfecting of his game, the secret to Kobe’s success is much less of a mystery.

Of course, what I have left unsaid is that maybe there is something different about such high achievers, that they simply “want it more than everyone else,” to use the old sports cliche.  Maybe that is something innate, or at least something that must be learned at an early age.  Kobe Bryant’s teammates certainly had every opportunity to copy his practice methods, but none of them did.  Maybe they didn’t have the competitive fire, and maybe they were okay with that.  And perhaps the myth of talent is what protects us from the question of why we haven’t achieved more.

I’ve been thinking about how to apply these principles of deliberate practice to my physics education, and while I certainly don’t have all the answers, I’ll be sharing some thoughts on the subject in a later post.

With this in mind, I filled out a bracket based on the rankings of their physics departments.  You should be able to see my full bracket here.  (In the case of schools where I didn’t know about either department, I took the higher seed.)

Things to look for:

• Good Second Round Matchups: Top-30 schools meet in the second round as rising Michigan State takes on the juggernaut of Maryland.  Maryland prevails on its way to an Elite Eight berth.  Cornell, one of the best departments in the tournament, gets a tough test in the second round, but is able to hold off Wisconsin.  Other potential upsets lurk in Minnesota-Pittsburgh and Texas A&M-Purdue, but the better-ranked Big Ten departments prevail.
• Seeding Issues: Ohio State, perceived to be a Top-25 department on the rise, nevertheless gets an extremely tough draw in the first round, facing powerhouse UC-Santa Barbara.  The South region is once again weak, as Notre Dame, ranked outside the Top 50, faces little resistance in making the Elite Eight.  The East region is stacked, with Cornell besting a strong field that includes Wisconsin, Washington, and Texas.
• Final Four: UC-Santa Barbara outlasts Maryland and their bevy of national lab affiliations to make it to the Final Four. They face my Minnesota department, which faced no real tests in its region, using its strong theoretical presence to carry the maturing experimental side, which could be dangerous in future tournaments.  Cornell survives the Region of Death, using its Ivy League clout to take out 3 Top-25 departments on its way.  Overall favorite UC-Berkeley makes quick work of Duke, Purdue, and Notre Dame.
• Champion: UCSB makes its run all the way to the championship round before running into big brother Berkeley.  Both departments battle early furlough trouble, and Joe Polchinski leads a High Energy attack for UCSB, pulling the string on several jump shots, keeping the contest close.  However, Berkeley has a legendary coach in J.D. Jackson, and is just too big and too balanced a department for UCSB to handle.  Berkeley prevails by a score of 137 to 3.14159265.

My take: No conclusive discovery of dark matter, but we couldn’t realistically expect that anyway.  However, there are two events that, while not definitively dark matter, can’t be ruled out either.  The announcement wasn’t earth-shattering, but it was nonetheless exciting.  It was cool for me to be in on what may be the early stages of a big and important discovery, both by watching the announcement live and by being at the institution that hosts the experiment.

My semester is over, so I’m at home, sitting on my couch, watching the CDMS talk streaming live. Here’s some of my thoughts as I watch:

4:11 CDT — Talk starts with an overview of dark matter. First detected by strange behavior in galaxies — gravity of stars and other visible matter alone cannot explain the motion.  Dark matter is probably made of particles, not a modified form of gravity.

4:13 — Feed is lagging, but doesn’t look like anything is getting cut out, it’s just choppy.

4:15 — Spherical cow model!

4:17 — Discussing the challenges for detection.  Need a low background, which is why it’s deep underground in an abandoned mine.  Also, neutrons can look like WIMPS (Weakly Interactive Massive Particles, the candidates for dark matter being searched for here).

4:19 — One of my favorite terms — fiducial volume.  It basically means the effective volume of the detector, where they can trust data points that seem to originate there.

4:23 — Wonder how many people are trying to watch this stream.  It seems like Kavli Institute doesn’t have the infrastructure to handle the size of their audience.

4:26 — FYI The Soudan Mine, in northern Minnesota, is also home to another major particle physics experiment — MINOS, which is measuring neutrino oscillations in the neutrino beam sent from Fermilab, just outside Chicago.  The size difference between the detectors is almost comical: CDMS has several small detectors that can be held in the hand. (Each detector is about 300 grams.  There are 30 detectors in five towers.)  MINOS has a 980-ton detector made of iron.

4:31 — Talking about results now!  Background is about .6 events

4:33 — Opening the box….and the feed completely cuts out!  Is this all a hoax? (lol, this is a joke.)

4:35 — Looks like the number of events is…. 2!  Paper will be on the ArXiv tonight.

4:37 — Discussion of the two events… time of nearly ideal detector performance.  Occurred on different detectors on different towers, several months apart.  Happened on their inner towers, where they feel their statistics are better.  Phonon data looks good, but “charge start time” (not sure what that is) might be a problem on one of the events.

4:40 — Charge start time, I think means when they see the shower of electrons at the detector.  For one of the events, this might have been too soon.

4:41 — From what I understand, they estimate a 23% chance that this signal is just due to background events.

4:42 — They cannot call it significant evidence of dark matter, but they can’t reject either event as not being dark matter.  In other words, it’s not necessarily dark matter, but they can’t say for sure that it isn’t.

4:44 — Now talking about the next step: SuperCDMS.  Installation and commissioning will start summer 2010 in the Soudan site in northern MN.  Eventual goal is to get SuperCDMS SNOLab, at the Sudbury Neutrino Observatory (SNO) in western Canada.

4:48 — Summary: cross section limit is less than 3.8 x 10^-44 cm^2 for WIMP mass of 70 GeV at 90% confidence.

4:54 — Q&A session now.  Feed cut out again.  Probably not worth the aggravation for me to hang around.  Thanks for following along!

You may have heard the wild rumors circulating around the physics blogosphere about the CDMS (Cryogenic Dark Matter Search) experiment taking place deep underground in an abandoned mine in northern Minnesota.  The rumor (which apparently started with this post at Resonaances) took some unusual behavior by the CDMS team, combined with the rumor of an article being published in Nature, led many to speculate that they were planning to announce detection of dark matter.

It turns out that these rumors were overly dramatic — apparently there is no Nature article, and Priscilla Cushman from the University of Minnesota has downplayed the rumors, calling them “lots of smoke and not much fire.”

However, they are still making dual announcements today at 5 o’clock EST, one at SLAC and one at Fermilab, and one will be webcast here.  So they have some sort of semi-major announcement, but that doesn’t necessarily mean a claim of detection.  It could be a significant improvement on their experimental limits, or maybe detections at a level that doesn’t allow them to make any big claims.  For more thoughts on what might be announced, and what it might mean, see this post.

And now for a little speculation of my own:

• In order to not spoil the surprise, no one in the CDMS collaboration is supposed to talk to the media or release their results in any way.  Apparently, they have extended this directive to young graduate students who don’t know anything anyway, which is amusing.
• It was announced that the results would be posted on the arXiv before the talks, which I assumed would mean in the postings for Dec. 17th, which should be out by now.  And in fact, all the other subfields have been posted, but not high energy experiment, which is where I believe the CDMS results would be.  Just a coincidence, or something else?
• There will also be a talk by CDMS at Minnesota on Friday, presenting what I believe will be the same results presented today.  This special talk is scheduled for one of the small seminar rooms, not the large colloquium lecture hall.  If an earth-shattering announcement were planned for Thursday, one might think that a larger room would be needed for Friday.  This makes me think that a smaller, but nevertheless important, announcement is coming.  The detection of dark matter will have to wait.

Later, I laughed at the irony of this situation.  You would think someone obsessed with Starcraft would be awkwardly left out of the football conversation, not the other way around.  But it was just another thing that made me realize that I’m not like these nerds.

Don’t get me wrong.  I’m a HUGE nerd.  I’m a physics graduate student, and I write a blog about it.  That’s enough for most of the population to put me stamp me with the NERD label.  And I’m fine with that.  I embrace my physics nerdiness.

But it’s the other interests that are generally assumed to go along with the math and science nerd stereotype where I fail to fit in.  I only like the most mainstream of science fiction and fantasy (Star Wars and Harry Potter).  Other than my Mario Kart skills and a brief obsession with Halo on my roommate’s XBox in college, I never really got into computer or video games.  I never read comic books.  I’m not all that interested in becoming technically adept in all the minutiae of computers.  Yet these are all the interests of your classic nerd.

(These are not just stereotypes, by the way.  I’m sure that you’ll find a statistically significant number of math/physics/computer science types like these things much more than I do.)

But I am still a nerd, just a nerd of a different sort.  To me, a nerd is just someone with a passion near obsession for what they like, and spend a lot of time talking about, thinking about, and participating in those activities.  I’ve even gone so far as to say that if you’re not a nerd about something, then you’re probably not all that interesting.

As for me, I like basketball.  I play it and watch it a lot, of course, but it goes beyond that.  I read many NBA blogs, watch analysis shows, and listen to podcasts on the bus, often hearing the same topic discussed by several different people.  Then I discuss those same topics with friends.  I look at statistics, and read about the new advanced statistics, and debates about which are better.  I play fantasy basketball, and spend free time doing research to inform my decisions in this hobby.  And of course, I’m a die-hard fan of my hometown Indiana Pacers.  If that’s not a nerdy level of commitment to a hobby, then I don’t know what is.

Of course, we still have to deal with the negative stereotype of nerds as being socially inept.  But this can be combated if we take the label NERD and attach it to ourselves proudly, and in contexts outside of the conventional stereotypes.

And besides, what are those social butterflies but texting, facebooking, party-going, social nerds?