Tag Archives: physics

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The monsters at the bottom of black holes!

BlackHole No, it’s not the title of some best-forgotten B-movie, but some high-brow astrophysics that – in all honesty – I can’t say I fully understand. But it’s something to do with quantum physics, entropy and super-massive black holes:

“Although Hawking radiation implies that black holes contain all this disorder, scientists have been puzzled as to where it all comes from. The collapsing stars that turn into black holes do not start out with nearly enough. How does the matter become so scrambled?

Frampton’s team argues that the extra entropy is generated by the random nature of quantum physics. This should sometimes allow a collapsing ball of matter to spontaneously transform into something called a “monster” – an arrangement of matter that has maximum disorder, with particles travelling at high speed in random directions.”

These “monsters” could help explain our way to a quantum theory of gravity, apparently. It’s times like this I wish I’d stuck with science instead of engineering. [Image courtesy NASA]

[tags]space, black holes, monsters, physics[/tags]
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Scientist creates dark matter in the lab!

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Black Corvette No, not that dark matter, but rather the darkest known material, about four times darker than the previous record holder. (Via PhysOrg.)

It’s a carpet of carbon nanotubes that only reflects 0.045 percent light, making it, as the Houston Chronicle puts it, “100 times darker than a black-painted Corvette,” (which seems like a fairly imprecise measurement standard, but never mind). The previous darkest known material was a nickel and phosphorus alloy that reflected about 0.16 percent of light.

The material’s ability to absorb light could be beneficial to solar panels and, since it minimizes the scattering of light, it could also benefit telescope manufacturers.

It also minimizes the scattering of light, making it a potential boon to telescope manufacturers.

(And, yes, you’re absolutely right: I posted this just so I could use that headline. The photo was a bonus.)

(Image: Wikimedia Commons.)

[tags]physics, materials, light[/tags]

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Inaudibility cloaks, like invisibility cloaks, theoretically possible

800px-Ripples_waves_bee It’s remarkable how often science advances by one scientist hear some other scientist say, “Such-and-such is impossible!”, responding, “Oh, yeah?” and then proving the first scientist wrong.

That seems to be what’s happened at Duke University, where Steven Cummer read a research report suggesting that it was impossible to build a 3-D acoustic cloak, a device that would make whatever was inside it disappear from sound waves. (Via ScienceBlog.)

Cummer and associate David Schurig had already reported a theory showing that a two-dimensional cloak as possible, and Cummer refused to believe that a 3-D cloak couldn’t also be built, especially considering researchers already know that a cloak invisible to electromagnetic waves is possible, and in fact have built one that operates at microwave frequencies.

“In my mind, waves are waves,” he said. “It was hard for me to imagine that something you could do with electromagnetic waves would be completely undoable for sound waves.”

So he sat down and figured out how such a cloak would work, and has shown that, in theory at least, it’s entirely possible to create an inaudibility cloak that allows sound waves to travel seamlessly around an object and continue on their way without distortion. With such a thing (which would have to be built from exotic metamaterials), you could build a stealth submarine that couldn’t be detected by sonar, or improve the acoustics of a concert hall by removing distortion caused by pillars or support beams.

And if you can build cloaks for electromagnetic and sound waves, what about other waves? How about structures unaffected by seismic waves, or boats unaffected by ocean waves?

The researchers’ full paper will be published in the January 11 Physical Review Letters.

(Image: Wikimedia Commons.)

[tags]physics, acoustics, stealth[/tags]

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The LHC on track for summer launch

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Part of the huge LHC colliderAs a Physics student doing a masters project on a computer simulation of CERN’s new particle supercollider, I’ve got a vested interest in the progress of the real thing. CERN is reporting good progress on the Large Hadron Collider (LHC) and thinks it is on track to start producing results this summer.

The LHC accelerates two beams of protons in opposite directions around its 27-kilometre diameter ring, until the two beams meet and collide with huge amounts of energy. From this energy, particle physicists hope new particles will form that we haven’t seen before. Chief among those prospective discoveries is the Higgs Boson, which would explain why the other particles have mass.

The Guardian’s weekly science podcast talks about the prospects of finding new science at the LHC, whilst Fermilab has a good summary of the other potential new things the LHC might find when it begins colliding later this year.

[via Science Daily, image by poluz]

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Laser fusion makes important steps

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Part of the UCLA tokamak fusion reactorThe quote physicists often say when asked about nuclear fusion is that ‘commercial fusion is 40 years away, but we’ve been saying that for 40 years’. Two main types of fusion are in development – ‘tokamaks’ like JET and ITER that use magnets to fuse hydrogen in a torus of plasma and those that shoot high powered lasers at pellets of hydrogen a few times a second, making bursts of energy.

Neither process is currently producing more energy than is put in to start the reaction but there have been some developments in laser technology that may help the latter approach. The EU has recently decided to fund a new high energy laser research project to build a working reactor. Laser fusion may ‘ignite’ and provide energy before the magnetic fusion research reaches the same point but the pulses of laser energy need to come much faster and more efficiently for this to be economically viable. Without considerable funding, the technological challenges of getting hydrogen to fuse will be insurmountable. However, fusion offers a real hope in the long term (30 years+) of providing clean energy.

[via the guardian, image of UCLA tokamak by r_neches]