More information on LIGO and gravitational waves.

1. Before LIGO made their discovery of gravitational waves public, the LIGO team worked with SXS, a project with the goal of simulating black holes and other extreme phenomena.

In the process, SXS produced a number of animations. They are fun to watch, but are also based on the best available science and state of the art numerical simulations. The animations are each about a minute at most. To look at these animations, go to one of these links...

http://www.black-holes.org/gw150914

https://www.youtube.com/playlist?list=PLLZ9goBDt4Z9AbZQClE1FsH9xflGdByec

2. Keith Riles (One of the LIGO team members) gave two lectures on gravitational waves shortly after the LIGO announcement. Each one is about one hour in length. 

"Gravitational Waves - Einstein's Audacious Prediction" (February 13, 2016)

https://www.youtube.com/watch?v=cxgO2gbPPfw

"The Hunt for Gravitational Waves - Was Einstein Right? (February 20, 2016)
https://www.youtube.com/watch?v=21Ong-aqwzY

Gravitational Waves Detected!

An earlier blog post discusses rumors of the detection of gravitational wave. At the time we had no official confirmation. Now we do.

Early today, the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced that it had made a direct observation of a gravitational wave for the first time. LIGO consists of two instruments, and both had recently been upgraded to make them more sensitive (and thus increase the chance of discovery). Back in September 2015, after the upgrade, a signal had been detected by both instruments. After analysis, it was determined that these signals were consistent with two black holes in a close "death spiral." They spiraled closer and closer until they collided and merged to form a single black hole. One of the black holes was 29 times the mass of the sun, the other 36 times the mass of the sun. This occurred about 1 billion years ago and resulted in a gravitational wave that was detected by both of the LIGO instruments. This result was keep secret (except for occasional "leaks" of information) until earlier today (February 11), when LIGO gave a press conference releasing details of the discovery.

This is an important result, but why?

These videos from PBS Digital Studios will be of interest.

A video recorded after the announcement, explaining what the discovery is all about...

LIGO's First Detection of Gravitational Waves https://youtu.be/gw-i_VKd6Wo

As you may have seen in an earlier blog post, rumors of this result were known for a while, here is a video recorded a few months ago, asking if gravitational waves have already been discovered. The fact is they already had been, but only a few people directly involved with LIGO knew this for sure.

Have Gravitational Waves Been Discovered? https://youtu.be/1Tstyqz2g7o

Some other videos discussing different aspects of General Relativity. General Relativity is Einstein's theory of gravity, and it predicts that gravitational waves exist.

"Are Space And Time An Illusion?": https://www.youtube.com/watch?v=YycAz...

"Is Gravity An Illusion?" https://www.youtube.com/watch?v=NblR0...

"Can A Circle Be A Straight Line?" https://www.youtube.com/watch?v=D3GVV...

"Can You Trust Your Eyes In Spacetime?": https://www.youtube.com/watch?v=P4rW_..5

General Relativity and Curved Spacetime https://youtu.be/AwhKZ3fd9JA?list=PLsPUh22kYmNAmjsHke4pd8S9z6m_hVRur

Rumor of Gravitational Wave Detection.

One of the predictions of General Relativity (Einstein's theory of gravity) is the existence of gravitational waves. In theory, anytime a massive object accelerates (that is any motion that is not constant straight line motion and not simple rotation) it should generate gravitational waves. So in theory the universe should be filled with gravitational waves.

However despite years of trying, no one has succeeded in detecting them.

But in the past few days rumors have been circulating that LIGO, a project to detect gravitational waves, has finally succeeded.

Einstein thought gravitational waves would be impossible to detect, and in fact they have been difficult to detect. The tiny signals must be separated from other signals (such as earthquakes and passing trucks). Each time a potential signal is detected, a statistic analysis is performed. This in essence asks "What is the likelihood this a real signal, not something that only looks real." This is expressed in terms of "sigma". The higher the sigma, the more likely the signal is real.

According to the rumor, LIGO has in fact detected signals that exceed "five sigma." Normally results like this are not released until solid confirmation has been made, but one of the physicists spilled the beans.

This may prove to be false; but it seems to be real. We should know for sure on February 11th when an official report from LIGO is scheduled to be published.

Those of you living in or near Ann Arbor, might be interested in two upcoming lectures, which by a happy coincidence are on this very topic. Both are by Keith Riles, professor of physics at the University of Michigan.

Saturday, February 13 10:30am: "Gravitational Waves - Einstein's Audacious Prediction."

Saturday, February 20 10:30am: "The Hunt for Gravitational Waves - Was Einstein Right?"

Both events are held in rooms 170 & 182 Weiser Hall (formerly the Dennison Building), University of Michigan Central Campus, 500 Church Street, Ann Arbor, Michigan, 48109

See https://www.lsa.umich.edu/physics/events/saturdaymorningphysics/schedule for more information about these lectures.

Save the date: a pulsar and a giant star are due to meet in 2018

This is going to be a highly anticipated meeting with plenty of fireworks, though be glad we are far enough away to enjoy the view safely.

Pulsars are rotating neutron stars, the leftover remnants of stars that once shone and were more massive than our sun. Pulsars "pulse" because they emit highly directional "beams" of electromagnetic energy from their poles, and we detect this every time they rotate and the beam crosses our path. This can happen thousands of times per second, making them excellent timekeepers!

Stars come in different sizes, and the one of interest in 2018 is about 15 times as massive as our sun. It is in the constellation Cygnus and is about 5,000 light years away from us. This star has a binary companion, a pulsar, that will actually move through its outer atmosphere in 2018. The orbit is fairly long at 25 years.

Check out the NASA press release for more information.

Barns Are Painted Red Because of the Physics of Dying Stars

http://www.smithsonianmag.com/smart-news/barns-are-painted-red-because-of-the-physics-of-dying-stars-58185724/?no-ist
I like articles such as this one that take mundane phenomena and link them to the stars. Though worth a read, punchline / TL;DR of this is that nuclear fusion stops generating excess energy at iron and this leads to an abundance of iron seeding the universe following supernovae, finding its way to rocky planets such as ours. Thus, iron oxide is plentiful, cheap, and just happens to make red paint.

Gravitational Wave Discovery Looks Doubtful In New Analysis

Update on the blog post of Wednesday, March 19, 2014 (http://lowbrows.blogspot.com/2014/03/confirmation-of-cosmic-inflation.html)

In March gravitational waves were discovered from the early universe (moments after the big bang). This discovery is now in doubt. New analysis suggests that dust within our own galaxy is responsible for much if not all of the signal. While it doesn't completely rule out the presence of gravitational waves, it is a significant setback.

For more information see: http://www.scientificamerican.com/article/gravitational-wave-discovery-looks-doubtful-in-new-analysis/

What is a black hole?

This post comes from NASA's Space Place. NASA's Space Place is a NASA educational website about space, Earth science, and technology.

NASA's Space Place in a SNAP! is a series of quick, narrated tours of animated infographics that illustrate key science concepts. Not only are they fun and entertaining on their own, they also come with a downloadable poster and a transcript of the video, making for a cross-disciplinary learning experience. The latest topic—black holes!

What is a black hole? A black hole is an area of such immense gravity that nothing—not even light—can escape from it. Find out what they are today at http://spaceplace.nasa.gov/black-holes. This post explains black holes in simple non-mathematical language.

Confirmation of Cosmic Inflation

In the late 1970's Alan Guth made a proposal: early in the history of the universe, shortly after the big bang, the universe went through a rapid and dramatic expansion. This expansion was so rapid it might be described as an "explosion" or a second big bang, though neither term is quite right. Instead this expansion was given the understated name "inflation."

Inflation caused the universe to expand faster than the speed of light. You might think this violates special relativity. But special relativity does not say that "nothing can travel faster than light" only that ordinary material objects cannot do so. It does not prevent space itself from expanding faster than the speed of light.

Up until recently inflation was purely a theoretical concept, there was no direct experiment evidence to support it. There was indirect evidence. There are observations which were not explained by the standard big bang theory. And these observations are neatly explained by inflation, but do not prove that inflation is true.

Observations made from telescopes near the south pole recently provided more direct evidence for inflation. By detecting gravitational waves from the early universe, scientists have direct evidence for the first time. See this article by Dennis Overbye in the New York Times...

http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html

'We may be able to watch dark energy turn on': U-M involved in unprecedented sky survey

"Through the Dark Energy Survey, which began Aug. 31, more than 200 researchers from 25 institutions, including U-M, will search for answers to a fundamental question about the cosmos: Why is its expansion speeding up?"

This is a paragraph from the University of Michigan news service article "'We may be able to watch dark energy turn on': U-M involved in unprecedented sky survey." This survey, if successful, may shed light on the nature of the mysterious dark energy.

http://www.ns.umich.edu/new/multimedia/videos/21661-we-may-be-able-to-watch-dark-energy-turn-on-u-m-involved-in-unprecedented-sky-survey

U-M Astronomy Stories

Here are some recent astronomy stories from the University of Michigan news service....

December 11, 2012: An older Vega: New insights about the star all others are measured by.

February 17, 2013:  Water on the moon: It’s been there all along.

March 15, 2013:  Young supernova remains found by U-M astronomer.

April 3, 2013:  Green Pea galaxies could help astronomers understand early universe.

April 8, 2013: Mars Science Lab update: What remains of Mars’ atmosphere is still dynamic.

Dark Matter, SUSY & DNA

In an earlier post I talked about the search for SUSY (supersymmetric) particles. SUSY particles might be an explanation for dark matter. Since each SUSY particle is paired with a normal particle (a Standard Model particle), they are often called SUSY partners. Most of the SUSY particles are predicted to be unstable, and so far there is no convincing experimental evidence that any of them exist. However theory predicts that the lightest of the SUSY particles will be stable. This LSP (lightest super-symmetric particle) might be the basis for dark matter.

In that post, I indicated that the LHC (Large Hadron Collider) might generate LSPs. Now, it seems very unlikely to do so over the short term. (There were results that suggested the existence of non-standard model particles, possibly SUSY particles, but those results didn't prove that the SUSY is correct or that LSPs exist. Other results seemed to disprove SUSY altogether, at least according to some).

However all is not lost. The LHC is undergoing enhancements. Once these enhancements are complete, the LHC will operate at higher energy; it is possible that operating at higher energy will create particles that could not be created at lower energy, possibly including the LSP.

There are other approaches. Current experiments, not associated with the LHC, are looking for dark matter particles (which are not necessarily LSPs). They include DAMA/LIBRA, CoGeNT and CREST-II. Results from some of these experiments have given hints of dark matter, but have failed to convince everyone.

In an arXiv paper published this past July, it was argued that a detector based on ssDNA (single stranded DNA) would have higher resolution than existing detectors, should make detection of dark matter particles easier, and may provide more convincing results. While DNA is more commonly associated with medical, genetic and biological applications, it can be and has been used in other fields such as physics.

So, we have several approaches, one or more of which might provide convincing evidence of dark matter particles in the future.

For more information see the following articles...

Andrzej Drukier, Katherine Freese, David Spergel, Charles Cantor, George Church, Takeshi Sano. arXiv:1206.6809 [astro-ph.IM] "New Dark Matter Detectors using DNA for Nanometer Tracking."  (Submitted on 28 Jun 2012). R. Bernabei, et al. arXiv:1007.0595 [astro-ph.CO] "Particle Dark Matter in DAMA/LIBRA." (Submitted on 4 Jul 2011). Henning Fleacher. CERN Document Server. https://cds.cern.ch/record/1498697 "Recent SUSY Results from CMS." Dan Hooper, Chris Kelso.  arXiv:1106.1066 [hep-ph] "Implications of CoGeNT's New Results for Dark Matter." (Submitted on 6 Jun 2011). Leo Stodolsky, et al. "The CRESST-II Dark Matter Search." 2012 J. Phys.: Conf. Ser. 384 012013. doi:10.1088/1742-6596/384/1/012013

Supernovas

Super-rare, super-luminous supernovae are likely explosion of universe's earliest stars