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Friday, December 19, 2014

Ripples From Space Dating to the Big Bang

English: Shows slices of expansion of universe...
English: Shows slices of expansion of universe without an initial singularity (Photo credit: Wikipedia)
An example of simulated data modelled for the ...
An example of simulated data modelled for the CMS particle detector on the Large Hadron Collider (LHC) at CERN. Here, following a collision of two protons, a is produced which decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue. (Photo credit: Wikipedia)
Well, this is a bit too scientific for me, but it is good to know. Just to avoid scientism - the belief that everything can be explained by science.

Read on...


CAMBRIDGE, Massachusetts – When scientists jubilantly announced last month that a telescope at the South Pole had detected ripples in space from the very beginning of time, the reverberations went far beyond the potential validation of astronomer’s most cherished model of the Big Bang.

It was the second time in less than two years that ideas thought to be radical just decades ago had been confirmed (so the optimists think) by experiment.

The first was the discovery of the Higgs boson, associated with an energy field that gives mass to other particles, announced in July 2012.

Now the South Pole telescope team, led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics, has presented physicists with another clue from what the Russian cosmologist Yakov B. Zeldovich once called the poor man’s particle accelerator – the universe itself.

The ripples detected by the telescope, Bicep2, were faint spiral patterns from the polarization of microwave radiation left over from the Big Bang.

These gravitational waves are the long-sought markers for a theory called inflation, the force that put the bang in the Big Bang: an antigravitational swelling that began a trillionth of a trillionth of a trillionth of a second after the cosmic clock started ticking. Scientists have long incorporated inflation into their standard model of the cosmos, but proving it had long been elusive.

Astronomers say they expect to be studying the gravitational waves from mountaintops, balloons and perhaps satellites for the next 20 years, hoping to gain insight into mysteries like dark matter and dark energy.

The question before astronomers and physicists now is understanding what caused inflation. What is this stuff that “turns gravity on its head” – as Alan Guth of Massachusetts Institute of Technology, a founder of inflation theory, has put it – and blew up the universe?

Einstein introduced the notion of antigravity into physics. For him it was known as the cosmological constant, a factor he used to account for the fact that the universe didn’t collapse.

He later abandoned the cosmological constant, calling it a mistake, but it was resurrected 15 years ago when astronomers discovered that the expansion of the universe was speeding up because of the mysterious force called dark energy. As with inflation, the repulsion is part of space itself: The bigger the universe gets, the more powerfully it pushes apart, resulting in an exponential runaway expansion.

Assuming they are confirmed, the Bicep2 results would eliminate most versions of inflation that have been proposed, including the Higgs, according to Andrei Linde, a physicist at Stanford University in California.

Knowing inflation’s identity could be crucial if scientists are to unwind cosmic history to the beginning, when they suspect the universe was ruled by a single unified force instead of the four we know today: gravity, electromagnetism and the strong and weak nuclear forces.

The Bicep2 waves seem to date from the time that theorists suspect electromagnetism and the weak force divorced the strong force, gravity having already gone its own way, but Dr.Linde says that could be a coincidence.

If the chain of evidence and reasoning holds up, however, the Bicep2 waves do bear witness to the most fervently hoped-for unification of all, or what John A. Wheeler of Princeton University in New Jersey once called “the fiery marriage “ of Einstein’s gravity, which shapes the universe, and quantum theory, which governs the behavior of atoms inside it.

According to inflation theory, the Bicep2 waves are magnified images of the hypothetical particles called gravitons that would transmit gravity in quantum theory. The gravitons, theory says, are produced by the same process by which black holes leak. It is known as Hawking radiation, after Stephen Hawking of Cambridge University, the renowned black hole theorist, who discovered it in 1973.

If the Bicep2 results are confirmed, and if astronomers agree that the ripples were gravitational waves from inflation, the discovery of Hawking radiation could win a Nobel Prize for Dr. Hawking.

Hawking radiation has been part of the physics firmament for decades; it’s the best-known prediction of quantum gravity.

Max Tegmark, a cosmologist at Massachusetts Institute of Technology, noted that some physicists had wondered whether gravity obeyed the dice-playing quantum principles that Einstein had disdained.

He said, “Now we know that gravity is indeed quantized, involving graviton particles.”

Taken from TODAY Saturday Edition, April 5, 2014

Wednesday, December 17, 2014

Genetic War on Pests May Hurt Benign Bugs

Mechanism of RNA interference
Mechanism of RNA interference (Photo credit: Wikipedia)
One molecule of the Dicer-homolog protein from...
One molecule of the Dicer-homolog protein from Giardia intestinalis, colored by domain (PAZ domain yellow, platform domain red, connector helix blue, RNase and bridge domains green). Dicer is an RNase that cleaves long double-stranded RNA molecules into short interfering RNAs (siRNAs) as a first step in the RNA interference response, and also initiates the formation of the RNA-induced silencing complex (RISC). (Photo credit: Wikipedia)
Left: (Image:1u04-argonaute.png) A full-length...
Left: (Image:1u04-argonaute.png) A full-length argonaute protein from the archaea species Pyrococcus furiosus. Right: (Right:Image:1ytu_argonaute_dsrna.png) The PIWI domain of an argonaute protein in complex with double-stranded RNA. The base-stacking interaction between the 5' base on the guide strand and a conserved tyrosine residue (light blue) is highlighted; the stabilizing divalent cation (magnesium) is shown as a gray sphere. (Photo credit: Wikipedia)

Scientists and Biotechnology companies are developing what could become the next powerful weapon in the war on pests – one that harnesses a Nobel Prize-winning discovery to kill insects and pathogens by disabling their genes.

By zeroing in on a genetic sequence unique to one species, the technique has the potential to kill a pest without harming beneficial insects. That would be big advance over chemical pesticides.

“If you use a neuro-poison, it kills everything,” said Subba Reddy Palli, an entomologist at the University of Kentucky who is researching the technology, which is called RNA interference, or RNAi. “But this one is very target-specific.”

But some specialists fear that releasing gene-silencing agents into fields could harm beneficial insects, especially among organisms that have a common genetic makeup, and possibly even human health.

“To attempt to use this technology at this current stage of understanding would be more naïve than our use of DDT in the 1950s,” the National Honey Bee Advisory Board said in comments submitted to the United States’ Environmental Protection Agency, which regulates pesticides.

The approach is of interest to bee keepers because one possible use, under development by Monsanto, is to kill a mite that is believed to be at least partly responsible for the mass die-offs of honeybees in recent years.

Monsanto also has applied for regulatory approval of corn that is genetically engineered to use RNAi to kill the western corn rootworm, one of the costliest of agricultural pests. The company is also trying to develop a spray that would restore the ability of its Roundup herbicide to kill weeds that have grown impervious to it.

Some bee specialists said they would welcome attempts to use RNAi to save honeybees. Groups representing corn, soybean and cotton farmers also support the technology.

For a decade, corn growers have been combating the rootworm by planting so-called BT crops that are genetically engineered to produce a toxin that kills the insects when they eat the crop. But rootworms are now evolving resistance.

RNA interference is a natural phenomenon that is set off by double-stranded RNA. DNA, which is what genes are made of, is usually double stranded, the famous double helix. But RNA, which is a messenger in cells, usually consists of a single strand of chemical units representing the letters of the genetic code. When a cell senses a double-stranded RNA, it acts as if it has encountered a virus. It activates a mechanism that silences any gene with a sequence corresponding to that in the double-stranded RNA.

Scientists quickly learned that they could deactivate virtually any gene by synthesizing a snippet of double-stranded RNA with a matching sequence.

The scientists who first unraveled this mechanism won the 2006 Nobel Prize in Physiology or Medicine, and it was initially assumed that most of the use would be in medicine – for example, drugs that could turn off essential genes in pathogens or tumors.

So far, researchers have found it difficult to deliver the RNA through a person’s bloodstream into the cells in the body where it is needed.

But beetles like the corn rootworm can simply eat the double-stranded RNA to set off the effect. One way to get insects to do that is to genetically engineer crops to produce double-stranded RNA corresponding to an essential gene of the pest.

Monsanto’s rootworm-killing corn is one of the first in which the crop has been engineered specifically to produce a double-stranded RNA.

Monsanto is also looking at putting RNA into sugar water fed to honeybees to protect them from the varroa mite. The way to fight the mite now is to spray pesticides that can also harm bees.

“We were trying to kill a little bug on a big bug,” said Jerry Hayes, the head of bee health at Monsanto.

If the RNAi is directed at a genetic sequence unique to the mite, the bees would not be harmed.

Some scientists are calling for caution, however. In a paper published last year, two entomologists at the United States’ Department of Agriculture warned that because genes are common to various organisms, RNAi pesticide might hurt unintended insects.

One study at the University of Kentucky and the University of Nebraska found that a double-stranded RNA intended to silence a rootworm gene also affected a gene in the ladybug, killing that beneficial insect.

In a paper prepared for a meeting earlier this year, E.P.A. scientists said RNAi represented “unique challenges for ecological risk assessment that have not yet been encountered in assessments for traditional chemical pesticide.”

Taken from TODAY Saturday Edition, March 22, 2014

Tuesday, December 16, 2014

Astronomical Encounter That May Test Theory of Relativity

larger animation
larger animation (Photo credit: Wikipedia)
The supermassive black holes are all that rema...
The supermassive black holes are all that remains of galaxies once all protons decay, but even these giants are not immortal. (Photo credit: Wikipedia)
Simulated view of a black hole in front of the...
Simulated view of a black hole in front of the Large Magellanic Cloud. The ratio between the black hole Schwarzschild radius and the observer distance to it is 1:9. Of note is the gravitational lensing effect known as an Einstein ring, which produces a set of two fairly bright and large but highly distorted images of the Cloud as compared to its actual angular size. (Photo credit: Wikipedia)

Black holes, the ultradense objects predicted by Einstein’s theory of general relativity, have extraordinary gravity: Everything is sucked in, even light, and virtually nothing leaks out.

Now, for the first time, astronomers may have a chance to watch as a gas cloud that has been hurtling toward the center of the Milky Way collides with a black hole that lies just 26,000 light-years from Earth. (While scientists expect to observe the event beginning in March or April, it occurred 26,000 years ago.) The gas cloud is as massive as three Earths – but no match for the black hole, Sagittarius A**, which has the mass of four million suns.

“This is a rare opportunity to witness spoon-feeding of a black hole,” said Avi Loeb, a theoretical astro physicist at Harvard. “Will the gas reach the black hole, and if so, how quickly? Will the black hole throw up or spit the gas out in the form of an outflow or a jet?

If the black hole devours a sizable chunk of the cloud, a digestive process that could take many months to years, fireworks could ensue. Heated to billions of degrees as it spirals inward, the doomed gas cloud may emit a last gasp of radiation, ranging from radio waves to X-rays.

“We will learn something, no matter what happens,” said Andrea Ghez, an astronomer at the University of California, Los Angeles, who has monitored the galactic center since 1995. Black holes are believed to be at the center of nearly every large galaxy.

The action is likely to unfold in two acts, said Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Germany.

His team discovered the gas cloud, G2, in 2011.

After the cloud, already stretched into a spaghetti-like strand by the black hole’s gravity, makes its closest approach to Sagittarius A*, its distance from the black hole will be about 200 times Earth’s distance from the sun. Nonetheless, the passage of G2 near Sagittarius A* might be near enough to plow into the outer edge of the swirling disk of matter believed to surround the black hole.

The shock wave generated by that encounter might create X-rays and radio waves that could be detected by telescopes.

If the cloud contains a star at its center, as some astronomers have proposed, it may generate more light, said Sera Markoff of the University of Amsterdam.

The encounter could have another effect: Disruptions in the cloud might alter the direction in which radio waves vibrate as they travel through. Simultaneous observations with telescopes tuned to different radio wavelengths might discern the waves’ twists, giving astronomers new details about the cloud’s properties, said Geoffrey Bower, a radio astronomer with the Taiwanese organization Asiaa, in Hilo, Hawaii.

But most of the potential fireworks are at least a year away, perhaps decades. That is how long it may take material torn from G2 to spiral inward through the black hole’s feeding disk, coming 100 times closer to the hole than it is now. At that location, gas becomes hot enough to radiate before it is swallowed.

Next year, the Event Horizon Telescope, an array of radio telescope, will gain enough acuity to discern the light that just misses being dragged into Sagittarius A*, but is bent into a halo. (That level of acuity could make out an orange on the surface of the moon, said the project’s leader, Sheperd Doeleman, of the Massachusetts Institute of Technology Haystack Observatory.) Deviations from the predicted shape of the halo would indicate Einstein’s theory of gravity needs revision.

For now, Professor Loeb said, astronomers are looking forward to the encounter. “The experience is as exciting for astronomers as it is for parents taking the first photos of their infant eating.”

Taken from TODAY Saturday Edition, March 8, 2014