David Kirkpatrick

August 2, 2010

Ever heard of a white hole?

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 6:22 pm

Me neither.

(And to be clear, the link goes to the physics arXiv blog and an astronomy story and not a NSFW site.)

July 13, 2010

Was our universe born in a black hole?

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 1:20 am

Maybe so.

From the link:

“Accordingly, our own Universe may be the interior of a black hole existing in another universe.” So concludes Nikodem Poplawski at Indiana University in a remarkable paper about the nature of space and the origin of time.

The idea that new universes can be created inside black holes and that our own may have originated in this way has been the raw fodder of science fiction for many years. But a proper scientific derivation of the notion has never emerged.

And:

That means the universe as we see it today can be explained by a single theory of gravity without any additional assumptions about inflation.

Another important by-product of Poplawski’s approach is that it makes it possible for universes to be born inside the event horizons of certain kinds of black hole. Here, torsion prevents the formation of a singularity but allows a HUGE energy density to build up, which leads to the creation of particles on a massive scale via pair production followed by the expansion of the new universe.

This is a Big Bang type event. “Such an expansion is not visible for observers outside the black hole, for whom the horizon’s formation and all subsequent processes occur after infinite time,” says Poplawski.

For this reason, the new universe is a separate branch of space time and evolves accordingly.

June 11, 2010

A bit on that other type of singularity

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 2:47 pm

I do a fair bit of blogging about the technological Singularity, but this post is about one the better known scientific singularities —  in this case the singularity that lies at the heart of a black hole and how to go about getting a glimpse of one in all its glory. All that would take is to destroy the black hole that hides the singularity. This physics arXiv blog post is something of an instructional guide on how to go about snuffing out a black hole. Pretty simple in theory, but you know the rest.

From the last link:

In general relativity, the mathematical condition for the existence of a black hole with an event horizon is simple. It is given by the following inequality: M^2 > (J/M)^2 + Q^2, where M is the mass of the black hole, J is its angular momentum and Q is its charge.

Getting rid of the event horizon is simply a question of increasing the angular momentum and/or charge of this object until the inequality is reversed. When that happens the event horizon disappears and the exotic object beneath emerges.

At first sight, that seems straightforward. The inequality suggests that to destroy a black hole, all you need to do is to feed it angular momentum and charge.

And:

To any ordinary physicist, a singularity is an indication that a theory has broken down and some new theory is needed to describe what is going on. It is a matter of principle that singularities are mathematical objects, not physical ones and that any ‘hole’ they suggest exists not in the fabric of the Universe but in our understanding of it.

Astrophysicists are different. They have such extraordinary faith in their theories that they believe singularities actually exist inside black holes. The likes of Roger Penrose and Stephen Hawking have even proved that singularities are inevitable in gravitational collapse.

For them, removing the event horizon around a black hole raises the exciting prospect of revealing a singularity in all its naked glory. When that happens, we will be able to gaze at infinity.

November 18, 2008

Billions of anti-matter particles

Very interesting research.

The release:

Billions of particles of anti-matter
created in laboratory

LIVERMORE, Calif. – Take a gold sample the size of the head of a push pin, shoot a laser through it, and suddenly more than 100 billion particles of anti-matter appear.

The anti-matter, also known as positrons, shoots out of the target in a cone-shaped plasma “jet.”

This new ability to create a large number of positrons in a small laboratory opens the door to several fresh avenues of anti-matter research, including an understanding of the physics underlying various astrophysical phenomena such as black holes and gamma ray bursts.

Anti-matter research also could reveal why more matter than anti-matter survived the Big Bang at the start of the universe.

“We’ve detected far more anti-matter than anyone else has ever measured in a laser experiment,” said Hui Chen, a Livermore researcher who led the experiment. “We’ve demonstrated the creation of a significant number of positrons using a short-pulse laser.”

Chen and her colleagues used a short, ultra-intense laser to irradiate a millimeter-thick gold target. “Previously, we concentrated on making positrons using paper-thin targets,” said Scott Wilks, who designed and modeled the experiment using computer codes. “But recent simulations showed that millimeter-thick gold would produce far more positrons. We were very excited to see so many of them.”

In the experiment, the laser ionizes and accelerates electrons, which are driven right through the gold target. On their way, the electrons interact with the gold nuclei, which serve as a catalyst to create positrons. The electrons give off packets of pure energy, which decays into matter and anti-matter, following the predictions by Einstein’s famous equation that relates matter and energy. By concentrating the energy in space and time, the laser produces positrons more rapidly and in greater density than ever before in the laboratory.

“By creating this much anti-matter, we can study in more detail whether anti-matter really is just like matter, and perhaps gain more clues as to why the universe we see has more matter than anti-matter,” said Peter Beiersdorfer, a lead Livermore physicist working with Chen.

Particles of anti-matter are almost immediately annihilated by contact with normal matter, and converted to pure energy (gamma rays). There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely anti-matter, and what might be possible if anti-matter could be harnessed. Normal matter and anti-matter are thought to have been in balance in the very early universe, but due to an “asymmetry” the anti-matter decayed or was annihilated, and today very little anti-matter is seen.

Over the years, physicists have theorized about anti-matter, but it wasn’t confirmed to exist experimentally until 1932. High-energy cosmic rays impacting Earth’s atmosphere produce minute quantities of anti-matter in the resulting jets, and physicists have learned to produce modest amounts of anti-matter using traditional particle accelerators. Anti-matter similarly may be produced in regions like the center of the Milky Way and other galaxies, where very energetic celestial events occur. The presence of the resulting anti-matter is detectable by the gamma rays produced when positrons are destroyed when they come into contact with nearby matter.

Laser production of anti-matter isn’t entirely new either. Livermore researchers detected anti-matter about 10 years ago in experiments on the since-decommissioned Nova “petawatt” laser – about 100 particles. But with a better target and a more sensitive detector, this year’s experiments directly detected more than 1 million particles. From that sample, the scientists infer that around 100 billion positron particles were produced in total.

Until they annihilate, positrons (anti-electrons) behave much like electrons (just with an opposite charge), and that’s how Chen and her colleagues detected them. They took a normal electron detector (a spectrometer) and equipped it to detect particles with opposite polarity as well.

“We’ve entered a new era,” Beiersdorfer said. “Now, that we’ve looked for it, it’s almost like it hit us right on the head. We envision a center for antimatter research, using lasers as cheaper anti-matter factories.”

Chen will present her work at the American Physical Society’s Division of Plasma Physics meeting Nov. 17-21 at the Hyatt Regency Reunion in Dallas. S.C. Wilks, E. Liang, J. Myatt, K. Cone ,L. Elberson, D.D. Meyerhofer, M. Schneider, R. Shepherd, D. Stafford, R. Tommasini, P. Beiersdorfer are the collaborators on this project.

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy’s National Nuclear Security Administration.

October 16, 2008

Black holes are violent

The more we learn about black holes, the more intense they sound. Here’s a report on the turbulent light — visual and X-ray — surrounding these phenomenae.

From the link:

The observations tracked the shimmering of the black holes simultaneously using two different instruments, one on the ground and one in space. The X-ray data were taken using NASA’s Rossi X-ray Timing Explorer satellite. The visible light was collected with the high speed camera ULTRACAM, a visiting instrument at ESO’s Very Large Telescope (VLT), recording up to 20 images a second. ULTRACAM was developed by team members Vik Dhillon and Tom Marsh. “These are among the fastest observations of a black hole ever obtained with a large optical telescope,” says Dhillon.

To their surprise, astronomers discovered that the brightness fluctuations in the visible light were even more rapid than those seen in X-rays. In addition, the visible-light and X-ray variations were found not to be simultaneous, but to follow a repeated and remarkable pattern: just before an X-ray flare the visible light dims, and then surges to a bright flash for a tiny fraction of a second before rapidly decreasing again.

May 15, 2008

Nanowire solar cells and black holes

From KurzweilAI.net, nanotech that may boost solar efficiency and black holes may have an escape hatch of sorts

Nanowires may boost solar cell efficiency, engineers say
PhysOrg.com, May 14, 2008

University of California, San Diego electrical engineers have created experimental solar cells spiked with nanowires that could lead to highly efficient thin-film solar cells of the future.

 
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Physicists Demonstrate How Information Can Escape From Black Holes
PhysOrg.com, May 14, 2008

Physicists at Penn State and the Raman Research Institute in India have discovered such a mechanism by which information can be recovered from black holes.

They suggest that singularities do not exist in the real world. “Information only appears to be lost because we have been looking at a restricted part of the true quantum-mechanical space-time,” said Madhavan Varadarajan, a professor at the Raman Research Institute. “Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time.”

 
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March 7, 2008

Artificial black hole created

Filed under: Science, Technology — Tags: , , , — David Kirkpatrick @ 12:59 pm

From KurzweilAI.net

Artificial black hole created in lab
physicswolrd, Mar. 6, 2008University of St Andrews physicists are the first to create an artificial black-hole system in which Hawking radiation could be detected.

The experiment used the refractive index of a fiber optic as the analogy for a gravitational field of a real black hole.
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