Were you to be close to a black hole, this program shows you what you might observe.
The optical appearance of the stellar sky for an observer in the vicinity of a black hole is dominated by bending of light, frequency shift, and magnification caused by gravitational lensing and aberration. Due to the finite apperture of an observer’s eye or a telescope, Fraunhofer diffraction has to be taken into account. Using todays high performance graphics hardware, we have developed a Qt application which enables the user to interactively explore the stellar sky in the vicinity of a Schwarzschild black hole. For that, we determine what an observer, who can either move quasistatically around the black hole or follow a timelike radial geodesic, would actually see.
For Linux and Windows only, although there are sample videos for non-downloaders or those on other machines.
The evidence comes from a study of how energy travels across the light-harvesting molecules involved in photosynthesis. The work has culminated this week in the extraordinary announcement that these molecules in a marine alga may exploit quantum processes at room temperature to transfer energy without loss. Physicists had previously ruled out quantum processes, arguing that they could not persist for long enough at such temperatures to achieve anything useful.
In 1905, Einstein came up with the concept of special relativity, published his paper on the photoelectric effect, finished his doctoral dissertation, devised the E=mc^2 concept, published a paper on Brownian motion, was approved for his doctorate, and turned 26.
If this doesn’t blow your socks off, then Hogan, who has just been appointed director of Fermilab’s Center for Particle Astrophysics, has an even bigger shock in store: “If the GEO600 result is what I suspect it is, then we are all living in a giant cosmic hologram.” […] Our everyday experience might itself be a holographic projection of physical processes that take place on a distant, 2D surface.
I really can’t do a good job, any job, of explaining magnetic force in terms of something else you’re more familiar with, because I don’t understand it in terms of anything else you’re more familiar with.
This is why science is so maddening for some and so great for others.
For the same reason that we have Space Shuttle launch delays, we’ll be able to tell exactly what trajectories our enemies could take between planets: the launch window. At any given point in time, there are only so many routes from here to Mars that will leave our imperialist forces enough fuel and energy to put down the colonists’ revolt.
However, if the theorists are right, before it ever finds the Higgs, the LHC will see the first outline of something far bigger: the grand, overarching theory known as supersymmetry. SUSY, as it is endearingly called, is a daring theory that doubles the number of particles needed to explain the world. And it could be just what particle physicists need to set them on the path to fresh enlightenment.
If you haven’t been keeping up with particle physics for the past few years (as I haven’t), this will bring you up to speed a bit.
The natural nuclear reactor formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, and a nuclear chain reaction took place. The heat generated from the nuclear fission caused the groundwater to boil away, which slowed or stopped the reaction. After cooling of the mineral deposit, short-lived fission product poisons decayed, the water returned and the reaction started again. These fission reactions were sustained for hundreds of thousands of years, until a chain reaction could no longer be supported. Fission of uranium normally produces five known isotopes of the fission-product gas xenon; all five have been found trapped in the remnants of the natural reactor, in varying concentrations. The concentrations of xenon isotopes, found trapped in mineral formations 2 billion years later, make it possible to calculate the specific time intervals of reactor operation: approximately 2 hours and 30 minutes
Nice try Fermi, but Mother Nature got there first.
Due to a mistranslation, Soviet reports on Enrico Fermi claimed that his work was performed in a converted “pumpkin field” instead of a “squash court”, squash being an offshoot of hard racquets.
When the first self-sustained nuclear chain reaction was achieved, a coded phone call was made by one of the physicists, Arthur Compton, to James Conant, chairman of the National Defense Research Committee. The conversation was in impromptu code:
Compton: The Italian navigator has landed in the New World. Conant: How were the natives? Compton: Very friendly.
Pumpkin field, tube alloy, the Italian navigator, the Manhattan Project…the building of the atomic bomb had no shortage of fanciful language.
Update: BLDGBLOG did a post on fossil reactors recently, which is probably where I got the link above in the first place.
Are the problems that have plagued the Large Hadron Collider and previous high-energy efforts (SSC, I’m looking at you here) a result of the Higgs boson travelling back from the future to meddle in its own discovery? A pair of scientists think it’s a possibility.
“It must be our prediction that all Higgs producing machines shall have bad luck,” Dr. Nielsen said in an e-mail message. In an unpublished essay, Dr. Nielson said of the theory, “Well, one could even almost say that we have a model for God.” It is their guess, he went on, “that He rather hates Higgs particles, and attempts to avoid them.”
This malign influence from the future, they argue, could explain why the United States Superconducting Supercollider, also designed to find the Higgs, was canceled in 1993 after billions of dollars had already been spent, an event so unlikely that Dr. Nielsen calls it an “anti-miracle.”
Nothing like a little science on the Moon, I always say.
Astronaut David Scott in 1971, from the Apollo 15 Lunar Surface Journal. Scott was part of the Apollo 15 crew, and applied Galileo’s findings about gravity and mass by testing a falcon feather and a hammer. The film, shown in countless high school physics classes, is the nerdy, oft-neglected cousin of Neil Armstrong’s space paces.
I don’t put people on pedestals very much, especially not physicists. Feynman [who won a 1965 Nobel for his work in particle physics] was pretty good, although not as good as he thought he was. He was too self-absorbed and spent a huge amount of energy generating anecdotes about himself. Fermi [who developed the first nuclear reactor] was good, but again with limitations-every now and then he was wrong. I didn’t know anybody without some limitations in my field of theoretical physics.
I read one such anecdote involving Gell-Mann in a book some years ago:
Richard Feynman, Gell-Mann’s chief competitor for the title of the World’s Smartest Man but a stranger to pretension, once encountered Gell-Mann in the hall outside their offices at Caltech and asked him where he had been on a recent trip; “Moon-TRAY-ALGH!” Gell-Mann responded in a French accent so thick that he sounded as if he were strangling. Feynman — who, like Gell-Mann, was born in New York City — had no idea what he was talking about. “Don’t you think,” he asked Gell-Mann, when at length he had ascertained that Gell-Mann was saying “Montreal,” “that the purpose of language is communication?”
Assuming you’re not in a big lecture hall and the professor shuts the door at the start of class, how long does it take for you and your classmates to deplete the oxygen enough to feel it?
Here’s a taste of the reasoning behind the answer:
So one person needs about 2lb of oxygen a day, or .9 kg. But how many liters is that? Oxygen has a molar mass of 16 grams, so oxygen gas, or O2, has a mass of 32 grams per mole. One mole of gas at standard pressure and temperature takes up 22.4 liters.
I don’t know if they brought this up on physicsbuzz yet, but lack of oxygen isn’t really uncomfortable (though it can kill you). Increase in CO2 is what triggers the apparent need to breath. I am pretty sure the minimum partial pressure of O2 is around 0.16 bar. Actually, that is the min recommended, I don’t know if that is the pass-out limit.
On July 17, 1969, The New York Times issued a correction related to an editorial the paper published in 1920 that dismissed the idea of rocket travel in the vacuum of space. The editorial read, in part:
That Professor Goddard, with his ‘chair’ in Clark College and the countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react — to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high school.
The correction stated:
Further investigation and experimentation have confirmed the findings of Issac Newton in the 17th Century and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error.
The Times regrets the error! Wish I’d written that next to a few muffed physics exam questions. Here’s a pretty good explanation of why rockets work in vacuums. (via @davidfg)
Law of Gravitation - An Example of Physical Law
The Relation of Mathematics and Physics
The Great Conservation Principles
Symmetry in Physical Law
The Distinction of Past and Future
Probability and Uncertainty - The Quantum Mechanical View of Nature
Seeking New Laws
If I ever write a book, it might have something to do with the two minds that govern creative expertise: the instinctual unconscious mind (the realm of relaxed concentration) and the thinking mind (the realm of deliberate practice). The tension between these two minds is both the key to and fatal flaw of human creativity. From the world of sports1, here’s Rockies pitcher and college physics major Jeff Francis describing the interplay of the minds on the mound:
Even though I do understand the forces and everything, there’s a separation when I’m pitching. If I throw a good pitch, I know what I did to do it, but there has to be a separation between knowing what I did and knowing why what I did helped the ball do what it did, if that makes any sense at all. If I thought about it on the mound, I’d be really mechanical and trying to be too perfect instead of doing what comes naturally.
But you don’t need to be a physics major to wrestle with the consequences of the conflict between the two minds. After an injury and subsequent surgery, Francis’ instinctual mind works to protect his body from further injury:
Francis repeatedly pulled the ball back in preparation to throw. But as he flashed his arm forward, his hand would, mind unaware, bring the ball back toward his ear rather than at full extension. It was his body essentially shortening the axis of his arm to decrease the force on his shoulder, protecting him from pain. And Francis could not stop it.
After his 10th pitch and first muffled groan of pain, he stopped.
“It’s hurting you?” Murayama said.
“Yeah,” Francis said.
“I can tell. You’re getting out ahead of your arm. Slow down, stay back a little more.”
“Does it look like I’m scared to throw a little?”
“Are you scared?”
“Not consciously.”
To fully recover and regain his former effective pitching motion, Francis will utilize his thinking mind to retrain his unconscious mind through deliberate practice to ignore the injury potential. (thx, adriana)
[1] Most of the examples I’ve cited over the years deal with sports, mostly because professional athletes are among the most trained, scrutinized, studied, and optimized creative workers in the world. For a lot of other professions and endeavors, the data and scrutiny just isn’t as evident. ↩
When they are passing in front of their stars, their atmospheres are backlit in a way that can make spectroscopic analysis of the different chemicals in their atmospheres comparatively easy: the wavelengths of light absorbed by the various chemicals will show up, in a tiny way, in the spectrum of the starlight. And this is what makes it possible to imagine looking at them for signs of life.
What scientists would look for are planets with unstable atmospheres, which James Lovelock said was an indication of life.
After the extragalactic planet post this morning, Sam Arbesman sent me a link to systemic, a blog dedicated to the search for extrasolar planets written by Greg Laughlin, one of the scientists involved in the effort. Here are two relevant posts. In Forward, Laughlin says we’re very close to finding a nearby Earth-like planet:
Detailed Monte-Carlo simulations indicate that there’s a 98% probability that TESS will locate a potentially habitable transiting terrestrial planet orbiting a red dwarf lying closer than 50 parsecs. When this planet is found, JWST (which will launch near the end of TESS’s two year mission) can take its spectrum and obtain resolved measurements of molecular absorption in the atmosphere.
In Too cheap to meter, Laughlin presents a formula for the land value of such a discovery that depends on how far away the planet is, the age of the star it orbits, and the star’s visual magnitude.
Applying the formula to an exact Earth-analog orbiting Alpha Cen B, the value is boosted to 6.4 billion dollars, which seems to be the right order of magnitude. And applying the formula to Earth (using the Sun’s apparent visual magnitude) one arrives at a figure close to 5 quadrillion dollars, which is roughly the economic value of Earth (~100x the Earth’s current yearly GDP)…
The idea is to use gravitational microlensing, in which a distant source star is briefly magnified by the gravity of an object passing in front of it. This technique has already found several planets in our galaxy, out to distances of thousands of light years. Extending the method from thousands to millions of light years won’t be easy, says Philippe Jetzer of the University of Zurich in Switzerland, but it should be possible.
The levitation trick works because giant magnetic fields slightly distort the orbits of electrons in the frog’s atoms. The resulting electric current generates a magnetic field in the opposite direction to that of the magnet. A field of 16 teslas created an attractive force strong enough to make the frog float until it made its escape.
After two to three weeks, the team found a small number of “triple tracks” in the plastic — three 8-micrometre-wide pits radiating from a point (see diagram, top right). The team says such a pattern occurs when a high-energy neutron strikes a carbon atom inside the plastic and shatters it into three charged alpha particles that rip through the plastic leaving tracks.
It’ll be interesting to see if this can be replicated and the source of the neutrons verified.
The reality in question — admittedly rather a small part of the universe — was the polarisation of pairs of photons, the particles of which light is made. The state of one of these photons was inextricably linked with that of the other through a process known as quantum entanglement. The polarised photons were able to take the place of the particle and the antiparticle in Dr Hardy’s thought experiment because they obey the same quantum-mechanical rules. Dr Yokota (and also Drs Lundeen and Steinberg) managed to observe them without looking, as it were, by not gathering enough information from any one interaction to draw a conclusion, and then pooling these partial results so that the total became meaningful.
That’s a relief, although the head of one of the group called their results “preposterous”, so perhaps we’re still not really here.
You may remember reading the New Yorker article on Garrett Lisi, a surfer, physicist, and snowboarder who came out of nowhere in 2007 to present a plausible Theory of Everything, “a unifying idea that aims to incorporate all the universe’s forces in a single mathematical framework”. I do but I missed this visualization of Lisi’s theory posted by New Scientist in late 2007. You may want to break out the bong for this one. (thx, matt)
Let me point to the Adjacent Possible of the biosphere. Once there were lung fish, swim bladders were in the Adjacent Possible of the biosphere. Before there were multicelled organisms, the swim bladder was not in the Adjacent Possible of the biosphere. Something wonderful is happening right in front of us: When the swim bladder arose it was of selective advantage in its context. It changed what was Actual in the biosphere, which in turn created a new Adjacent Possible of the biosphere. The biosphere self consistently co-constructs itself into its every changing, unstatable Adjacent Possible.
If the becoming of the swim bladder is partially lawless, it certainly is not entailed by the fundamental laws of physics, so cannot be deduced from physics. Then its existence in the non-ergodic universe requires an explanation that cannot be had by that missing entailment. The universe is open.
We determined that, generally speaking, the gravity in each Mario game, as game hardware has increased, is getting closer to the true value of gravity on earth of 9.8 m/s^2. However, gravity, even on the newest consoles, is still extreme.
In Super Mario 2, Mario experiences a g-force of 11 each time he falls from a ledge, a force that would cause mere humans to black out. In Madden 2006, the game’s fastest cornerbacks can run the 40 in 2.6 seconds. (via waxy)
It’s true that after 300 years, nuclear waste is still about 100 times more radioactive than the original uranium that was removed from the earth. But even this isn’t as scary as it sounds. If the waste is stored underground in such a way that there’s only a 10 percent chance that 10 percent of it will leak — which should be more than doable — the risk will be no worse than if we had never mined the uranium in the first place.
Muller asserts that safe nuclear power is a solved technical problem and that the use of it is a political issue.
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