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Brian Koberlein
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Now that we've detected gravitational waves, we can have fun with them. If we were fairly close to a black hole merger, could we feel the gravitational waves they produce?

We can detect gravitational waves with sophisticated equipment, but could gravitational waves ever be so strong we could feel them?
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probably if we were close enough to eventually get absorbed... I am doubting it
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Direct Detection Of Gravitational Waves

Two black holes circle each other in a gravitational dance. Spiraling closer over thousands of years, they eventually get so close that they can no longer keep dancing. In a fraction of a second these two black holes merged into a single, larger black hole. It’s an event that happens fairly regularly throughout the universe. But this time, a group of humans 1.3 billion light years away measured the ripples in space and time produced during the merger.

It’s hard to overstate the significance of our first direct detection of gravitational waves. On the one hand the discovery announced in Physical Review Letters confirmed what we’ve suspected for decades: gravitational waves exist. By itself that’s not a big deal, since they are a natural result of general relativity, and we’ve had indirect evidence of gravitational waves since the 1970s. The direct detection of gravitational waves is yet another confirmation of what we’ve already known. On the other hand, this opens up an entirely new window to the universe.

The paper released today has been peer reviewed, which is comforting given the BICEP2 incident. It’s also a remarkably strong result given the extreme sensitivity necessary to detect gravitational waves. The advanced LIGO experiment consists of two detectors located in Louisiana and Washington. To qualify as a real detection, there must be a nearly simultaneous event in both detectors with the same basic form. In the above image, the event in question matches up quite well. It also matches the expected signal as calculated from numerical simulations of merging black holes. This is a strong, clear signal confirming gravitational waves.

The data is good enough that we actually know quite a bit about the merging black holes. The larger black hole had a mass of about 36 Suns, while the smaller one had a mass of about 29 Suns. When the two black holes merged they formed a single black hole of about 62 Suns. You might notice those numbers don’t add up. That’s because in the process of merging, about 3 solar masses worth of energy was radiated away as gravitational waves. That’s a huge amount of energy to release in a fraction of a second, which is why we can detect it so clearly from more than a billion light years away. We also know some broader characteristics, such as how fast the final black hole rotates, roughly where in the sky the merger occurred and the cosmological redshift of the event (which is how we know its distance).

While the detection of gravitational waves is the biggest news, this is also further confirmation that black holes are real. If they weren’t black holes their merger would create a burst of light or neutrinos like a stupendous supernova, which wasn’t seen. This is also the first clear observation of a black hole merger.

In the history of human civilization humans looked up at the sky and saw light. When Galileo first raised his telescope to the sky he saw light. Over the centuries we’ve widened the range of what light we can observe. We’ve launched telescopes into space to see types of light not visible from the ground. With the exception of some neutrinos and cosmic particles, the field of astronomy is rooted in our ability to observe and analyze light.

But now we can listen to the very fabric of space and time.

Paper: B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).Observation of Gravitational Waves from a Binary Black Hole Merger. Phys. Rev. Lett. 116, 061102 (2016)

In the history of human civilization humans looked up at the sky and saw light. Now we can listen to the very fabric of space and time.
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Thank u very much.........

..
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Everyone wants Pluto to be a planet. But if that's to be the case, how do we distinguish what is and isn't a planet?
When you argue that Pluto should be a planet, you open a pandora's box of questions about just what the definition of a
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+Sheikh Lubnaa by mankind standard's. 
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Bang On

The dominant model for the origin of our Moon is the impact model. In this model, about 4.5 billion years ago proto-Earth was hit by a Mars-sized body known as Theia. It’s generally been thought that the collision was somewhat off-center, causing the remnants of Theia and some outer layer material from Earth to form the Moon. But new evidence suggests the collision was more head-on.

If the Earth-Moon system was caused by an off-center collision with Theia, then we would expect to see close similarities in the chemical compositions the Earth and Moon, but still some differences. Earlier research found some differences in the amount of isotopes, such as the ratio of oxygen-17 to oxygen-16 differing by about 12 parts per million between the Earth and Moon. But new work analyzing oxygen isotopes in lunar rocks and volcanic rocks on Earth found their oxygen isotopes to be indistinguishable. Since oxygen is common in both rock samples, the fact that they are indistinguishable suggests that the material forming the Earth and Moon were mixed together before they formed. This could be achieved by a more head-on collision between proto-Earth and Theia.

If that’s the case, then much of Theia became a part of Earth’s core, and our planet is actually the product of two worlds. It’s an interesting twist on the impact origin of the Moon.

Paper: Edward D. Young, et al. Oxygen isotopic evidence for vigorous mixing during the Moon-forming giant impact. Science Vol. 351, Issue 6272, pp. 493-496 (2016)

New evidence suggests Earth may have been formed from two worlds.
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IS IT A PLANET???
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Widdershins

Ever wonder why clockwise and counterclockwise are the directions they are? It all has to do with the motion of the Sun.

On Earth the Sun appears to rise in the east and set in the west. If you are in the northern hemisphere, the Sun will make this east-west journey to the south of you. As a result, the shadow of a sundial will move clockwise over the course of the day. Clockwise motion is the motion of a sundial. So counterclockwise is against the sunward motion, or widdershins as it is sometimes known.

Of course in the southern hemisphere the Sun takes a northern path from east to west. The shadow of a sundial therefore moves counterclockwise. Since our standard of clocks originated in the northern hemisphere, so does our notion of clockwise.
Ever wonder why clockwise and counterclockwise are the directions they are? It all has to do with the motion of the Sun.
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Noce
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What Are The Odds That Aliens Exist?

Recently the star KIC 8462852 (aka Tabby’s Star) has made news again because of its strange behavior. Possible explanations for its varying brightness (such as comets) don’t seem to fit the observational data, which has some speculating that the star’s behavior could be explained by the presence of an alien civilization. While many astronomers admit that is a possibility, they don’t think aliens are the likely cause. For one, mysterious behavior is not enough to conclude the cause is aliens. For another, the likelihood that an alien civilization actually exists is still a matter of some debate.

The odds of an alien civilization coexisting with humans is often calculated by the Drake equation. It was first proposed by Frank Drake in 1961. Simply take the rate at which stars form in our galaxy and multiply it by the fraction of stars with planets, the average number of planets per star that could support life, the fraction of those that actually develop life, the fraction of life bearing planets that develop civilization, the fraction of civilizations that have detectible signals, and finally the length of time a civilization might last. Crunch the numbers and you have the number of civilizations in our galaxy capable of communicating with us.

When Drake first proposed the equation, the values for each term were largely unknown, but we now have good estimates for many of them. We know that most stars have planets, and the odds of a potentially habitable planet is actually quite high, possibly as high as 100 billion in our galaxy alone. Unfortunately the really important factors of the Drake equation are still completely unknown. On how many potentially habitable planets does life actually arise? How many of those give rise to civilizations? How long does a typical civilization last? No idea. Depending on the answer to those questions the number of civilizations in our galaxy could range from hundreds of thousands to only one.

The equation was never intended to give an absolute number, though it is often used that way. There are also alternatives such as the Sara Seager’s equation, which focuses on our ability to detect civilizations indirectly rather than requiring active communication. Just because an alien civilization is quiet, that doesn’t mean we can’t see evidence for them. Seager’s approach is to focus on stable red dwarf stars with known potentially habitable worlds. Since red dwarf stars are by far the most common, the odds that we’d find alien life near such a star is higher. She then focuses on planets that transit their home star from our vantage point and are near enough that we have a chance of observing the effects of the planet’s atmosphere on the star’s light. She estimates that there might be two inhabited worlds might be detectable in the next ten years. Of course this presumes that life forms readily on a habitable planet and survives billions of years, which might not be the case.

What make’s Tabby’s Star particularly interesting is that it hints at being evidence of an artificial structure the size of a solar system, such as a Dyson sphere, which is something only highly advanced civilizations could create. Of course the big underlying assumption here is that the more advanced a civilization is, the more likely it will build such a structure. The idea was first presented by Nikolai Kardashev in 1964, who proposed a classification of civilizations based upon their energy use. Type I civilizations harness the resources of their home planet, such as humans today. Type II harness almost the full energy of their home star, possibly through technology such as Dyson spheres. Species within the Star Trek universe would typically be Type II. Type III are civilizations that can harness the energy of an entire galaxy, such as the Asgard of the Stargate universe. Carl Sagan later generalized the Kardashev scale to a logarithmic function of energy use, and estimated that we were at about 0.7.

The Kardashev scale presumes that more advanced civilizations will necessarily demand more energy. Humans have so far lent credence to this idea, since our modern global civilization consumes much more energy than earlier agrarian civilizations. If our human population and demands for technological convenience grows, we will likely expand out into the solar system with a continued rise in energy consumption. But such a future is not guaranteed. It’s also possible that we will instead reach a stable and sustainable population level, and combined with increasing energy efficiency our energy consumption may flatten. Technological civilizations may stabilize at type I rather than continuing up the scale.

That’s the real challenge with calculating the odds. Everything we’ve pinned down so far point to a good chance that life forms on planets across the Universe, but there’s still too many unknowns.
The likelihood that an alien civilization actually exists is still a matter of some debate.
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On Forbes and AdBlock

A few times a month I'll write a post on Forbes and link to it on Google+. Every time I do I get grief about how Forbes prevents readers from using AdBlock, and how I should post the full article on G+. So I feel I should clarify a few points.

To begin with, Forbes is perfectly within their right to control whether adblockers are banned. Forbes also has exclusive rights to my posts there for a limited time, so I cannot post them in full on G+. While I do get a modest bit of money for putting articles on Forbes, the main reason I'm writing there is because my university sees Forbes as a prestigious publication. Being a professor is still my primary job, and that means I have to justify to my employer that blog writing has impact and merit. Posting to Forbes makes it easier to justify.

If you don't like my posts being adblocked by Forbes, there are several things you can do:

1. Be patient. Forbes only has exclusive rights to posts for a limited time. They all appear on my own blog (briankoberlein.com) after a week or so. You'll be able to read it there without any ads. Everything I write (with very few exceptions) eventually shows up on my blog.

2. Promote the crap out of my blog. Besides the Forbes posts, the other justification I can use with my employer is just how widely read my work is. The way I can do that is through the analytics of my blog. There are 1200 posts on the site that can be shared on various social media sites. The more readers and views I get, the easier it is to justify to my university.

3. Contribute financially. My website doesn't have any ads. It doesn't generate revenue with clickbait headlines and copypasta articles. It has an RSS feed that gives you the entire articles. You can sign up for an email list that sends you new articles directly. And I post the full text to articles here on G+. The guiding principle of my blog is to provide it freely without hype and without ads. If you like that approach rather than the ad-driven approach of sites like Forbes, then consider supporting it.

I enjoy writing about new discoveries in astronomy. I'm glad folks like my work. But I hope you understand that I have to strike a balance that I hope is reasonable and fair.

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+Brian Koberlein Yeah, I don't like the Forbes adblocking, but...

1. Be patient.
     Already waiting on you. Whenever something is being passed around on social media I'm waiting to hear the no-hype non-clickbait straight scoop that you provide.

2. Promote the crap out of my blog.
     Been there, done that. On and off the internet I let people know you are IMO at the top of science writing.

3. Contribute financially.
       My contribution to your Patreon is small, wish it could be more. As it is I feel like I'm getting a whole lot more from you than you're getting from me. Thank you.
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Gravitational waves have been detected, which is a really big deal. But what causes gravity to produce waves?

Gravitational waves have been directly detected. Why do gravitational waves exist, and why is this such a big discovery?
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I LOVE THIS PHOTO! I LOVE TO SEE THE FRESH WATER WITH THE REFLECTION OF THE LIGHT AROUND IT!
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Not With A Bang But A Whimper

While large stars end their lives as brilliant supernovae, our Sun will face a much quieter end. As it runs out of usable hydrogen to sustain it, the Sun will expand into a red giant for a time, and then what matter it has remaining will collapse into a white dwarf. And then what?

When a white dwarf forms it is extremely hot. The initial surface temperature of a white dwarf is about a million Kelvin. This makes them extremely bright for their tiny size. But unlike main sequence stars that maintain their heat through nuclear fusion, white dwarfs rely upon electron pressure to keep themselves from collapsing under their own weight. They have no way to generate heat on their own, and so they simply radiate away heat and light, gradually cooling to become a black dwarf.

It’s estimated that it would take a thousand trillion (10^15) years for a white dwarf to become a black dwarf, which is much longer than the mere billions of years our Sun will shine as a main sequence star. This assumes there is no other mechanism to heat a white dwarf. In models of dark matter, dark matter particles would interact with the regular matter of the white dwarf, keeping it warm, perhaps a trillion times longer. Over that time scale, if protons are unstable their decay could extend the cooling time a bit more.

But all that would simply delay the inevitable. As the universe continues to expand and cool, our Sun and other white dwarfs will be among the last beacons of light before fading into the cold and dark.

As it runs out of usable hydrogen to sustain it, the Sun will expand into a red giant for a time, and then what matter it has remaining will collapse into a white dwarf. And then what?
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Is a star or a planet???
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Cycles Of Time

We like marking time by the Sun. Its rising and setting marks a day, and its path along the ecliptic marks a year. The solar year seems to be our favorite marking of time. Its cycle follows the seasons, and so we have lots of annual celebrations, including our own special day. Of course there are lots of other ways we could mark our time.

We could note the seasons of the Moon, shifting from new moon to full and back to new over about 29.5 days. For young children such a clock is sometimes used, but as we get older a lunar month seems too short to take much notice. Of course the lunar cycle is a bit out of sync with the solar year, but every 19 years the Moon and Sun come back into sync. This Metonic cycle could be used as a basic of celebration, but nearly two decades seems too long for a personal celebration.

We could mark time by the Soros cycle, which follows the pattern of eclipses. While eclipses happen 4 times a year, the relative alignments of the Earth, Moon and Sun cycle through a pattern of about 18 years. But since each eclipse isn’t seen from everywhere on Earth, such a pattern isn’t particularly commemorative.

If we lived longer we might celebrate other cosmic cycles, such as the 1,400 year Sothic cycle of ancient Egypt, which marked the rising of Sirius just before sunrise on the first day of the year. Or the Great Year marking the 25,800 years it takes for the rotational axis of the Earth to make one complete precession. Or perhaps the galactic year marking the Sun’s 250 million year journey around the galaxy.

But our lives span an intermediate time between mayflies and immortals, and so the journey of the Earth around the Sun marks our cycles of time.
We like marking time by the Sun.
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+Lisa Paron​ - banned it is.
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Watching A Black Hole From Your Back Yard

Black holes don’t emit light directly, but material around a black hole often does. As gas and dust falls toward a black hole, it’s often compressed and superheated, causing it to emit light. Usually the light we see is in the form of x-rays and gamma rays, since they can penetrate material surrounding a black hole. But recently we’ve observed visible light from material near a black hole, and with a decent telescope you could observe it from your back yard.

V404 Cygni is a black hole with a mass of about 12 Suns. Orbiting it is a star a bit smaller than our Sun. Every few years the star passes close enough to the black hole that some of its outer material gets captured by the black hole. The captured material falls into the black hole, and as it does the material is superheated and emits x-rays. We know the x-rays we observe come from near the black hole because they vary in brightness over a short time. Since the fluctuation of brightness depends upon the scale of the object emitting light, quick variations mean the source must be relatively small, and therefore near the black hole.

The emission of x-rays can also heat up material farther from the black hole, causing it glow in the visible spectrum. The visible glow from the black hole is much more steady, and doesn’t vary quickly. But when V404 Cygni became active, one of my colleagues, Michael Richmond, decided to check it out with RIT’s 8-inch telescope. He made the video you can see above. What he found was that the brightness of V404 Cygni varied in the visible spectrum in the same way it varied in the x-ray spectrum. This meant the visible light came from the same region close to the black hole.

What’s amazing about this is that Rochester isn’t known for having the best viewing conditions, and 8-inch telescopes are pretty common among hobbyists. So it wouldn’t be to difficult for folks to observe an active black hole from their back yard.

Paper: Mariko Kimura, et al. Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni. Nature 529, 54–58 (2016)
It is possible to observe a black hole from the comfort of your back yard.
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Heisenberg's Mirror

Heisenberg’s uncertainty principle is the foundational concept of quantum theory. It’s also commonly misunderstood, which leads to a great deal of confusion about what quantum theory really says about the universe.

The uncertainty principle is often presented in terms of an observer effect. Suppose you want to measure the position of an electron. One way to do this is to shine light in the electron’s direction. When a photon scatters off the electron, you can measure how it scatters and determine where the electron is. But of course when the photon scatters off the electron it would cause the electron to scatter off in some direction. Measuring the position thus makes the electron’s motion (momentum) somewhat uncertain. Since any measurement of an electron’s position or momentum would make one or the other uncertain, there is a limit to what can be measured about the electron.

While that makes a nice intuitive picture, it’s completely wrong. The uncertainty principle isn’t a limit on what you can measure, but an inherent property of quantum objects. The reason you can’t precisely measure the position and momentum of an electron is not because you’re experiment is sloppy, but because electrons don’t have a precise simultaneous position and momentum.

Heisenberg’s uncertainty is what leads to all the strange aspects of quantum objects, such as particle-wave duality and quantum tunneling. Unfortunately, quantum systems are often portrayed as weird things that keep changing the rules to keep you in the dark, or only become real when you look at them. Such descriptions assume that quantum systems should behave like everyday objects. But the universe is far more subtle. The everyday, common sense ideas we have about the world are often only rough approximations that human-sized objects seem to follow.

To really understand the universe, we sometimes have to view things through Heisenberg’s mirror.

To really understand the universe, we sometimes have to view things through Heisenberg's mirror.
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I joined this because i wanted to have a better understanding of science but you guys are way out of my league i only understand 30pct of what your saying
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The Universe is amazing, let me tell you.
Introduction
An astrophysicist and physics professor at Rochester Institute of Technology.  Author of "Astrophysics Through Computation" with David Meisel.  Creator of the science outreach project Prove Your World, developing a science television show for children.

If you like my writing, consider supporting me on Patreon.

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