Large Hardon Collider

[Squah]

Carl Sagan's Cosmos coming back to TV next year, hosted by Neil Degrasse Tyson.


Yiss

[Salodin]

http://player.ooyala.com/player.js?h...wUj1nMRI&width

Don't know if the video format works on bg, but Neil deGrasse being funny as usual. His humor always gets me lol.

[Kryssan]

http://player.ooyala.com/player.js?h...wUj1nMRI&width

Don't know if the video format works on bg, but Neil deGrasse being funny as usual. His humor always gets me lol.

That link doesn't work for me. Clicking on it just creates a massive string of text, like viewing a html file in source.



In news:

Will we ever have nuclear fusion ( BBC - link )

A rather good, if quick, look at the challenges faced. I find it a bit amusing though that for ICF they don't mention NiF...

In the era of global climate change, and concerns about humanity's long-term reliance on fossil fuels, many think the solution lies in alternative sources of energy, including nuclear power. All our nuclear power plants are based on fission: splitting heavy atoms into lighter components in a controlled fashion. Though fission is safe when all goes well, the fuel is radioactive, waste disposal can be problematic, and as the Fukushima disaster showed there is a high cost to accidents.

Nuclear fusion is in principle cleaner and comes from a cheaper, more abundant fuel source: an isotope of hydrogen called deuterium can be extracted from water and only helium is produced as waste. From The Matrix to SimCity 2000 to political dreamers, fusion has often been seen as an inevitability for society. However, despite decades of work nuclear fusion remains a dream. As the joke goes fusion is the power of the future – and always will be.

That's not because creating a sustained fusion reaction – in which more energy is produced than is required to start and maintain the process – is impossible or even terribly hard to achieve (at least by high-energy particle physics standards). The most infamous example of a fusion reaction is the hydrogen bomb, which sacrificed control and safety for the sake of violence and death. Fusion reactors obviously need to have more stringent requirements.

Cosmic collider

To see what's needed to create a sustained reaction, let's look to the best-known fusion reactors of all: stars. In the core of a star like the Sun, strong gravitational pressure forces together hydrogen plasma – an equal mixture of protons and electrons. Extreme conditions of 15 million-degree-temperatures and high pressures mean that protons have enough energy to overcome their mutual repulsion for each other, allowing the attractive forces to kick in. When protons fuse together they are converted into neutrons and release a lot of energy.

Bluntly stated, we can't recreate those conditions, even if we wanted to. Stars have a sufficiently large mass to contain the hydrogen plasma by the force of gravity alone, but we don't have that option, so physicists have to confine plasma using electromagnetism instead. Researchers can also start with deuterium or tritium plasma instead of hydrogen to lower the energy required to start fusion. (Tritium is a hydrogen isotope consisting of a proton and two neutrons; unlike normal hydrogen and deuterium, it's unstable and therefore harder to keep around.) However, the temperature and pressure still needs to be high, so it requires a larger energy input than fusion liberates, which defeats the purpose.

Part of the difficulty lies in the nature of plasma. If you put a normal neutral gas, such as oxygen, in a container you can increase both pressure and temperature by compressing it. Plasma, on the other hand, consists of charged particles at sufficiently high temperatures to melt the container walls. Also, without maintaining conditions carefully, the electrons tend to reunite with protons, creating a neutral hydrogen gas that's useless for fusion; it's imperative that the container trapping the plasma contain no gas, for similar reasons.

Some hope lies in using elements other than hydrogen, as these contain more than one proton per nucleus. That increases the electric repulsion and in some cases can make the energy barrier to fusion even higher. While some fusion reactions involving helium, lithium, or boron are areas of active research, a major problem is that these materials are far rarer on Earth than hydrogen.

Hot doughnuts

All is not lost, however. Researchers are pursuing several possible solutions to the fusion problem, mostly based on clever methods for confining or compressing deuterium. The oldest of these is magnetic confinement, in which strong magnetic fields act as the “walls” of a container.

The best-known incarnation of this is the tokamak, first built in the Soviet Union in the 1950s. In a tokamak, deuterium and tritium are injected into a doughnut, or torus-shaped chamber, and heated to the point at which its electrons break free. Magnetic fields running along the centre contain and squeeze the plasma, and the high temperatures within the plasma then facilitate fusion. However, even the best tokamak designs – including the Joint European Torus (JET) in the United Kingdom and the Tokamak Fusion Test Reactor (TFTR) in the United States – haven't broken the barrier of making more energy than is required to keep the plasma hot and trapped. Much hope is being placed on Iter (International Thermonuclear Experimental Reactor), a €15 billion ($22 billion) project designed to build the world’s largest tokamak in the south of France. Iter is expected to commence operation at the end of this decade, with the first proper fusion tests scheduled for 2028. But it has been dogged by logistical issues – last month the US Senate spending panel voted to stop contributions to the project.

Many think another method called inertial confinement provides the best hope for a workable fusion reactor. This uses bombardment by high-energy photons – X-rays – to confine and compress a pellet of hydrogen and its isotopes. Successive X-ray pulses emanate from a large number of lasers completely surrounding the pellet, doing the work of heating, ionising, and compressing the hydrogen to the point where it can fuse. The biggest barrier to a working model lies in the X-ray lasers, which require a lot of energy to operate, but researchers at laboratories such as SLAC in the United States and the European X-ray Free Electron Laser are actively working to solve the problem.

The Z Machine at Sandia National Laboratory in the United States is a hybrid between magnetic and inertial confinement. Though the Z Machine itself is not a fusion reactor (and in fact is partly used for developing models for nuclear weapons), the powerful magnetic fields and X-rays it produces are part of a project in which a pellet of hydrogen is repeatedly bombarded with intense pulses of light to compress it.

There are other methods for confinement and compression, and more will no doubt be developed. Another path is aimed at lowering the energy barrier to deuterium fusion: forming molecules using muons instead of electrons. Muons are the heavier, unstable cousins of electrons. (We all have family members like that, I think.) Their presence in a molecule of two deuterium atoms brings the nuclei much closer together, consequently making fusion much more likely. However, once the energy cost of making muons and creating molecules using them is added in, muon-catalysed fusion no longer becomes cost-effective.

So the question is will we find a way around any of these problems? As with many things, it depends on human scientific ingenuity, and the practical limits placed upon it. Fusion research is relatively expensive, so investing in it is an exercise in hope. More precisely it is hope that once a sustainable fusion reactor is invented, it will repay the investment many times over.

Will we ever create a black hole ( BBC - link )

Before the Large Hadron Collider (LHC) began operations in 2008, a small but noisy group of people were in uproar. The LHC would be so powerful, they thought, that when it rammed protons together at a significant fraction of light-speed, it could produce exotic particles or small black holes. Earth, they claimed, could be destroyed as a result.

As many physicists quickly pointed out, most of these disaster scenarios were impossible, the remainder being so unlikely as to be unworthy of discussion. For one thing, the Universe has much more powerful accelerators than the LHC – supernovas and black holes – and particles from these hit Earth's atmosphere all the time. We're safe from those cosmic rays, so we're safe from the LHC's experiments.

But let’s turn the question around. What if we wanted to make a black hole, and we knew that there would be no danger in doing so – could we do it?

All black holes, great and small

Black holes have a gravitational field so intense that nothing can escape them, not even light. The ones that we know of were born from the deaths of stars much more massive than our Sun (the stellar-mass black holes), or through processes during the early Universe we don't yet fully understand that form the supermassive black holes found at the centre of most galaxies, including our own. In both of these cases, we observe the black holes via telescopes indirectly, through the behaviour of matter swirling around them, and through their gravitational influence on other bodies.

As befits astronomical objects, every black hole yet seen is massive; however, that doesn't automatically rule out the possibility of very low-mass black holes – especially if they can be produced by other means than the deaths of stars. The principle behind the LHC is that high-energy collisions can produce new particles, as governed by the rules of the fundamental forces: electromagnetism, the weak force, the strong force, and – if the energies involved are astoundingly high – gravity. For example, the famous Higgs boson doesn't exist under ordinary conditions because its lifetime before decaying to other particles is infinitesimally brief. However, interactions with sufficient energy involving the weak force can generate it for long enough for LHC scientists to record it.

From a particle physics point of view, we can think of tiny black holes as a new type of particle, governed by gravity. Gravity is by far the weakest of the fundamental forces; the reason it governs planets and stars is because any two masses attract each other, while electric charges either attract or repel, averaging out to zero. Gravity becomes stronger not only when two masses grow bigger, but also when two masses get closer together. At a very small distance it reaches the same strength as the other forces. In fact, “very small” is a profound understatement: the distance, known as the Planck length, is approximately 1020 times smaller than an atomic nucleus. (In numbers, the Planck length is about 1.6 × 10-35 metres, compared to the 1 x 10-15 metre size of a nucleus.) The difference in scale between the Planck length and that of particle physics is much greater than the comparison between particles and everyday objects.

To make matters worse, there's a kind of reciprocal relationship between scale and energy: probing small scales requires a very large amount of energy. The relevant energy scale to the Planck length – the Planck energy – is about 1015 times greater than the LHC can manage. An obviously insurmountable problem, one would naturally assume.

Exotic layers

But one idea lurking around the edges of standard physics is the notion that our reality consists of more than the four dimensions of space-time. Various physicists over the last century have added one or more extra dimensions to the mix for a variety of reasons: unifying the forces of nature, solving some tricky problems in particle physics, or even explaining why gravity is so weak compared to other forces. Superstring theory is probably the best known of these ideas, with seven additional dimensions curled up tightly together. However, the scale of standard-issue superstrings physicists refer to is still the Planck length, so that won't bring us any closer to creating a laboratory black hole.

Other theories call for “large” extra dimensions: ones that are still microscopic, but significantly larger than the Planck length. The larger size brings them that much closer to measurable energy scales. As an analogy, the size of these “large” extra dimensions is akin to the thickness of a piece of paper, while the flat sides of the paper would be akin to the “normal” dimensions of space-time.

Unfortunately there are too many of these theories to describe them all, but we can split them into two major categories: ones in which normal matter – quarks, electrons, etc. – is confined to our normal four-dimensional space-time, and ones in which those particles can traverse the dimensions too small for us to see directly. The first category is particularly interesting because the extra dimensions can be as large as a millimetre, while the second requires the scale of new dimensions to be very small.Nevertheless, gravity would travel through these extra dimensions just fine, leading to modifications of the force law on the scale at which the extra dimensions become important. Those modifications could even allow particle colliders to make miniature black holes. Producing such things would be a lovely bit of evidence for those hypothetical extra dimensions.

Vanishing point

There are several big “ifs” in this discussion: if large extra dimensions exist and if they are sufficiently large to bring them within reach of what the LHC is powerful enough to create, it may be possible to make a black hole with mass comparable to elementary particles. If we were somehow successful at this, then we would still have to detect the black hole, which wouldn’t necessarily be straightforward.

According to a widely-accepted (albeit untested) theory, black holes decay via a process called Hawking radiation, named after physicist Stephen Hawking who discovered this. The rate of radiation and decay depends on the size of the black hole, with the massive black holes decaying very slowly and the smaller ones evaporating quickly. That's a major reason why we don't need to fear creating a black hole at the LHC: if physicists managed the trick, the black hole would so small that it would vanish in a fraction of a fraction of a second. That's too little time to pose a danger to particles in the detection chamber, let alone the world around it.

But the result of the evaporation would be a burst of particles, and their numbers, types, and masses would be the spoor or ‘signature’ of the black hole, much as the observed decay products at the LHC were the signature of the Higgs boson. However, specific predictions of Hawking radiation’s signature depend on some unknowns, as well as which version of large extra dimensions is the correct one – that is, if any of them correspond to reality in the first place. In other words, the theorists aren't being helpful: they're providing too many possibilities of what kinds of particles to look for in particle detectors.

When theory is cacophonous, experiment can reveal the missing melody. The detectors at colliders could provide the all-important clues if they detect particle signatures that are difficult to explain with the standard particles that we know of today. Similarly, the current absence of black hole detections at the LHC places limits on the maximum size of extra dimensions, and this, in turn, reduces the list of plausible more-than-four-dimensions theories.

That doesn’t necessarily give us a black hole. But even a failure to find a miniature black hole will tell us something about the nature of gravitation.

[Salodin]

NDT on bill Maher. Not exactly science stuff, but he's great on the show and I know others would like to see it.

[myreality]

Mutation in key gene allows Tibetans to thrive at high altitude

A gene that controls red blood cell production evolved quickly to enable Tibetans to tolerate high altitudes, a study suggests. The finding could lead researchers to new genes controlling oxygen metabolism in the body.

An international team of researchers compared the DNA of 50 Tibetans with that of 40 Han Chinese and found 34 mutations that have become more common in Tibetans in the 2,750 years since the populations split. More than half of these changes are related to oxygen metabolism.

The researchers looked at specific genes responsible for high-altitude adaptation in Tibetans. "By identifying genes with mutations that are very common in Tibetans, but very rare in lowland populations we can identify genes that have been under natural selection in the Tibetan population," said Professor Rasmus Nielsen of the University of California Berkeley, who took part in the study. "We found a list of 20 genes showing evidence for selection in Tibet - but one stood out: EPAS1."

The gene, which codes for a protein involved in responding to falling oxygen levels and is associated with improved athletic performance in endurance athletes, seems to be the key to Tibetan adaptation to life at high altitude. A mutation in the gene that is thought to affect red blood cell production was present in only 9% of the Han population, but was found in 87% of the Tibetan population.

"It is the fastest change in the frequency of a mutation described in humans," said Professor Nielsen.

There is 40% less oxygen in the air on the 4,000m high Tibetan plateau than at sea level. Under these conditions, people accustomed to living below 2,000m – including most Han Chinese – cannot get enough oxygen to their tissues, and experience altitude sickness. They get headaches, tire easily, and have lower birth rates and higher child mortality than high-altitude populations.

Tibetans have none of these problems, despite having lower oxygen saturation in their tissues and a lower red blood cell count than the Han Chinese.

Around the world, populations have adapted to life at high altitude in different ways. One adaptation involves making more red blood cells, which transport oxygen to the body's tissues. Indigenous people in the Peruvian Andes have higher red blood cell counts than their countrymen living at sea level, for example.

But Tibetans have evolved a different method. "Tibetans have the highest expression levels for EPAS1 in the world," said co-author Dr Jian Wang of the Beijing Genomics Institute in Schenzhen, China, a research facility that collected the data. "For Western people, after two to three weeks at altitude, the red blood cell count starts to increase. But Tibetans and Sherpas keep the same levels," he said.

"I just summitted Everest a few weeks ago," added Dr Wang. He said the Sherpas and Tibetans were much stronger than the Westerners or lowland Chinese on the climb. "Their tissue oxygen concentration is almost the same as Westerners and Chinese but they are strong," he said "and their red blood cell count is not that high compared to people in Peru."

"The remarkable thing about Tibetans is that they can function well in high altitudes without having to produce so much haemoglobin," said Prof Nielsen. "The entire mechanism is not well-understood – but is seems that the gene responsible is EPAS1."

Nielsen said the gene is involved in regulating aerobic and anaerobic metabolism in the body (cell respiration with and without oxygen). "It may be that the [mutated gene] helps balance anaerobic versus aerobic metabolism in a way that is more optimal for the low-oxygen environment of the Tibetan plateau," he said.

Writing in Science, where the results are published today, the authors say: "EPAS1 may therefore represent the strongest instance of natural selection documented in a human population, and variation at this gene appears to have had important consequences for human survival and/or reproduction in the Tibetan region."

Dr Wang said future research will focus on comparing the levels of EPAS1 expression in the placentas of Tibetan and Han Chinese women.

http://www.theguardian.com/science/2...etans-altitude

[Kyreth]

Potentially sad news for the Chinese moon rover:

http://www.cnn.com/2014/01/27/world/...html?hpt=hp_t2

Given the roughly 50% fail rate on lunar missions, it was likely China's first would go through something like this. Damn shame though, we need more countries to reach past Earth and start making that highway to the stars- Luna, Mars, the asteroid belt at least.

[myreality]

http://prl.aps.org/abstract/PRL/v112/i3/e030602

Nanoscale Heat Engine Beyond the Carnot Limit

We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the efficiency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the efficiency at maximum power of up to a factor of 4 is reached, largely exceeding the Carnot bound.

No clue what this means but it sounds cool.

[Cantih]

http://space.io9.com/was-that-just-a...rst-1582373688

The Swift Gamma-Ray Burst Mission just saw something very bright in the Andromeda Galaxy, and we don't know what it is. It was either a Gamma-Ray Burst or an Ultraluminous X-Ray Object, but either way it will be the closest event we've ever observed.

The article is long, but well worth the read.

[Waraji]

Dude Holy Shit @ SpaceX Dragon 2. Propulsion Landing Capsule wuuuuuuuuut?!

[Cantih]

Good god man, add a link for something like this

Jump to 3min for the meat.
And the rest of the stuff
https://www.youtube.com/watch?featur...Ao6VRtA#t=2483

[Waraji]

The presentation video wasn't up yet. :/

[Obiron]

Dude Holy Shit @ SpaceX Dragon 2. Propulsion Landing Capsule wuuuuuuuuut?!

I may be wrong, but I thought they had already announced something like this. Last month when they launched the Falcon 9 I remember reading (I haven't found the article for proof) that part of that mission was to test propulsion landing. They were still going to dump Dragon into the ocean, but they would use its re-entry to determine the feasibility of a soft landing for future manned crews. I'll need to find the article because I remember thinking the same thing back then. Maybe that was just a precursor to this official unveiling?

Edit:
Here's the article I was referring to. It was the rocket they were referring to last month, not the capsule. Pretty awesome that they'll be able to safely land both the rocket and the capsule for re-use.

[myreality]

http://english.farsnews.com/newstext...13930631000263

On/Off Switch for Aging Cells Discovered

In our bodies, newly divided cells constantly replenish lungs, skin, liver and other organs. However, most human cells cannot divide indefinitely–with each division, a cellular timekeeper at the ends of chromosomes shortens. When this timekeeper, called a telomere, becomes too short, cells can no longer divide, causing organs and tissues to degenerate, as often happens in old age. But there is a way around this countdown: some cells produce an enzyme called telomerase, which rebuilds telomeres and allows cells to divide indefinitely.

In a new study published September 19 in the journal Genes and Development, scientists at the Salk Institute have discovered that telomerase, even when present, can be turned off.

“Previous studies had suggested that once assembled, telomerase is available whenever it is needed,” says senior author Vicki Lundblad, professor and holder of Salk’s Ralph S. and Becky O'Connor Chair. “We were surprised to discover instead that telomerase has what is in essence an ‘off’ switch, whereby it disassembles.”

Understanding how this “off” switch can be manipulated–thereby slowing down the telomere shortening process–could lead to treatments for diseases of aging (for example, regenerating vital organs later in life).

Lundblad and first author and graduate student Timothy Tucey conducted their studies in the yeast Saccharomyces cerevisiae, the same yeast used to make wine and bread. Previously, Lundblad’s group used this simple single-celled organism to reveal numerous insights about telomerase and lay the groundwork for guiding similar findings in human cells.

“We wanted to be able to study each component of the telomerase complex but that turned out to not be a simple task,” Tucey said. Tucey developed a strategy that allowed him to observe each component during cell growth and division at very high resolution, leading to an unanticipated set of discoveries into how–and when–this telomere-dedicated machine puts itself together.

Every time a cell divides, its entire genome must be duplicated. While this duplication is going on, Tucey discovered that telomerase sits poised as a “preassembly” complex, missing a critical molecular subunit. But when the genome has been fully duplicated, the missing subunit joins its companions to form a complete, fully active telomerase complex, at which point telomerase can replenish the ends of eroding chromosomes and ensure robust cell division.

Surprisingly, however, Tucey and Lundblad showed that immediately after the full telomerase complex has been assembled, it rapidly disassembles to form an inactive “disassembly” complex — essentially flipping the switch into the “off” position. They speculate that this disassembly pathway may provide a means of keeping telomerase at exceptionally low levels inside the cell. Although eroding telomeres in normal cells can contribute to the aging process, cancer cells, in contrast, rely on elevated telomerase levels to ensure unregulated cell growth. The “off” switch discovered by Tucey and Lundblad may help keep telomerase activity below this threshold.

[BaneTheBrawler]

fuck yes. i actually learned about the telomeres in a series of books called Area 51. It's... really weird but it pretty accurately describes telomeres, as far as i can tell.

[Kuya]

What did the books say about telomeres?

[BaneTheBrawler]

that they're the end-caps on your DNA and as you get older they run out and your DNA starts accumulating errors that cause aging. telomerase is what creates new telomeres. so if you can turn telomerease on and off you can make enough telomeres to prevent aging without causing cancer.

pretty much the same thing the article said, only the books followed that to its fantastic conclusion. among other weird shit.

[Insanecyclone]

Immortality is around the corner

[BaneTheBrawler]

p. much. hence the fuck yes.

[kuronosan]

Nice.

Telomeres basically are junk strands that protect coding sequences.

[Waraji]

I first heard of Telomeres in Mr. Nobody. Excitement Intensifies.

You technically can't live forever just because of detelomerization, but it will definitely extend life expectancy by a substantial amount. We'll still have to deal with life crippling or ending diseases. But it would give the former more time to find cures.