Gravity waves, Dark Matter and Wormholes.

[astr0144]

How Gravitational Waves Really Work

Rejoice all you visual learners: If the physics behind the workings of gravitational space waves, a.k.a. ripples in spacetime, is a head-scratching topic, the European Space Agency uploaded today this new video that breaks it all down.

Using a table cloth, marble, and a cube made of tungsten (which sits in for an actual cube of gold-platinum), scientist Paul McNamara explains that the not-so-flat universe makes for an environment in which gravitational waves can occur.



The European Space Agency's LISA Pathfinder lifted off on December 3.

How this all works is a point of importance for McNamara and his ESA team because on December 3 they launched the LISA Pathfinder on a Vega rocket from Europe's spaceport in Kourou, French Guiana. The Pathfinder is now on the way to demonstrate technology for observing low-frequency gravitational waves from space.

If the LISA Pathfinder is able to prove that these waves ripple through space it's going to have a huge impact on space and physics research. Why? Because it would provide evidence for a little thing called Albert Einstein's theory of general relativity.

On December 2, 1915, Einstein predicted that gravitational waves are ripples in the fabric of spacetime and that everything that is in the universe can cause it to change its shape.

While space news seems to be dominated by Mars probes and the space race of private industries, proving one of the most famous theories of physics would be pretty damn cool.


http://www.huffingtonpost.com/inverse/how-gravitational-waves-r_b_8749744.html?ncid=txtlnkusaolp00000592

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Tiny dark matter stars would harbour particles that act as one



"You will be assimilated." In Star Trek, members of the strange and sinister race known as the Borg would utter this threat as if one. Their behaviour could be echoed in space if dark matter exists in a particular form: if so, it could create Borg-like stars in which every particle is in the same state at the same time.

Dark matter accounts for 80 percent of the matter in the universe, but we can't observe it directly and its constituents are a mystery.

One theory is that dark matter could be made of particles called axions. Unlike protons, neutrons and electrons that make up ordinary matter, axions can share the same quantum energy state. They also attract each other gravitationally, so they clump together.

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Together, those two properties mean that the clumps would exist as a Bose-Einstein condensate (BEC) – a state of matter in which all the particles occupy the same quantum state, according to calculations by Chanda Prescod-Weinstein at the Massachusetts Institute of Technology and her colleagues.

"They act like one super-atom together," says Prescod-Weinstein. But those clumps are prone to fracturing, she adds. "The configuration the axions 'want' to settle into is not one giant BEC." Rather, they break apart into smaller clumps, which the team calls Bose stars.

Asteroid-sized
These would have formed when the universe was a mere 47,000 years old and should survive to this day, she says. Such stars would be totally dark and relatively tiny, the size of the asteroid Ceres and about 20 times as dense.

Dark matter is hard to study because it does not interact much with ordinary matter, but axion dark matter could theoretically be observed in the form of Bose stars, if they are orbiting a pulsar. Under the right conditions, the interaction between the pulsar and the axions could produce radiation we can pick up, says Prescod-Weinstein.

This would be like a naturally occurring, space-based version of the Axion Dark Matter Experiment at the University of Washington in Seattle, which uses a large superconducting magnet to search for axions.

"I'm sure that experimentalists would express some scepticism about that," she says. "But I tend to be optimistic that the universe is weirder than we think it is."

"It's a great paper, and we agree with their conclusions," says Rohana Wijewardhana at the University of Cincinnati, Ohio, whose team has done similar calculations.

Wijewardhana adds that if a Bose star crashed into Earth, we might be able to observe its effects. It's not something we need worry about, either: because a Bose star would interact weakly with matter, we would only see small gravitational effects even if the entire thing passed right through Earth.

https://www.newscientist.com/article/dn28632-tiny-dark-matter-stars-would-harbour-particles-that-act-as-one/


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What are Wormholes?

In science fiction, wormholes are a method often used to travel great distances across space. Are these magic bridges really possible?

With all my enthusiasm for humanity's future in space, there's one glaring problem. We're soft meat bags of mostly water, and those other stars are really really far away. Even with the most optimistic spaceflight technologies we can imagine, we're never going to reach another star in a human lifetime.

Reality tells us that even the most nearby stars are incomprehensibly far away, and would require vast amounts of energy or time to make the journey. Reality says that we'd need a ship that can somehow last for hundreds or thousands of years, while generation after generation of astronauts are born, live their lives and die in transit to another star.

Science fiction, on the other hand, woos us with its beguiling methods of advanced propulsion. Crank up the warp drive and watch the stars streak past us, making a journey to Alpha Centauri as quick as a pleasure cruise.

You know what's even easier? A wormhole; a magical gateway that connects two points in space and time with one another. Just align the chevrons to dial in your destination, wait for the stargate to stabilize and then just walk... walk! to your destination half a galaxy away.



Yeah, that would be really nice. Someone should really get around to inventing these wormholes, ushering in a bold new future of intergalactic speedwalking. What are wormholes, exactly, and how soon until I get to use one?.

A wormhole, also known as an Einstein-Rosen bridge is a theoretical method of folding space and time so that you could connect two places in space together. You could then travel instantaneously from one place to another.

We'll use that classic demonstration from the movie Interstellar, where you draw a line from two points, on a piece of paper and then fold the paper over and jab your pencil through to shorten the journey. That works great on paper, but is this actual physics?

As Einstein taught us, gravity isn't a force that pulls matter like magnetism, it's actually a warping of spacetime. The Moon thinks it's just following a straight line through space, but it's actually following the warped path created by the Earth's gravity.

And so, according to Einstein and physicist Nathan Rosen, you could tangle up spacetime so tightly that two points share the same physical location. If you could then keep the whole thing stable, you could carefully separate the two regions of spacetime so they're still the same location, but separated by whatever distance you like.

Climb down the gravitational well of one side of the wormhole, and then instantaneously appear at the other location. Millions or billions of light-years away. While wormholes are theoretically possible to create, they're practically impossible from what we currently understand.

Albert Einstein, pictured in 1953. Photograph: Ruth Orkin/Hulton Archive/Getty Images Ruth Orkin/Getty
Albert Einstein, pictured in 1953. Photograph: Ruth Orkin/Hulton Archive/Getty Images Ruth Orkin/Getty
The first big problem is that wormholes aren't traversable according to General Relativity. So keep this in mind; the physics that predicts these things, prohibits them from being used as a method of transportation. That's a pretty serious strike against them.

Second, even if wormholes can be created, they'd be completely unstable, collapsing instantly after their formation. If you tried to walk into one end, you might as well be walking into a black hole.

Third, even if they are traversable, and can be kept stable, the moment any material tried to pass through – even photons of light – that would make them collapse.

There's a glimmer of hope, though, because physicists still haven't figured out how to unify gravity and quantum mechanics.

This means that the Universe itself might know things about wormholes that we don't understand yet. It's possible that they were created naturally as part of the Big Bang, when the spacetime of the entire Universe was tangled up in a singularity.

Astronomers have actually proposed searching for wormholes in space by looking for how their gravity distorts the light from stars behind them. None have turned up yet.

One possibility is that wormholes appear naturally like the virtual particles that we know exist. Except these would be incomprehensibly small, on the Planck scale. You're going to need a smaller spacecraft.

Artist illustration of a spacecraft passing through a wormhole to a distant galaxy. Image credit: NASA.
Artist illustration of a spacecraft passing through a wormhole to a distant galaxy. Image credit: NASA.
One of the most fascinating implications of wormholes is that they could allow you to actually travel in time.

Here's how it works. First, create a wormhole in the lab. Then take one end of the wormhole, put it on a spacecraft and fly away at a significant percentage of the speed of light, so that time dilation takes effect.

For the people on the spacecraft, just a few years will have occurred, while it could have been hundreds or even thousands for the folks back on Earth. Assuming you could keep the wormhole stable, open and traversable, then traveling through it would be interesting.

If you passed in one direction, you'd not only move the distance between the wormholes, but you'd also be transported to the time that the wormhole is experiencing. Go one direction and you move forward in time, go the other way: backwards in time.

Some physicists, like Leonard Susskind think this wouldn't work because this would violate two of physics most fundamental principles: local energy conservation and the energy-time uncertainty principle.

Unfortunately, it really seems like wormholes will need to remain in the realm of science fiction for the foreseeable future, and maybe forever. Even if it's possible to create wormholes, then you've got the keep them stable and open, and then you've got to figure out how to allow matter into them without collapsing. Still, if we could figure it out, that'd make space travel very convenient indeed.

If you could set up two ends of a wormhole to anywhere in the Universe, where would they be? Tell us your ideas in the comments below.

http://www.universetoday.com/123730/what-are-wormholes/

[COSMO]

Hi Astro,



Gravitational Wave Theory is just that...a theory.  Gravitational waves haven't been discovered yet, which I find odd.  If they are generated as the theory proposes, then we should be able to detect them pretty easily I would think.  But they have eluded detection so far.  I wonder if that model is incorrect.  I wonder what would happen if spacetime is compressible?  Maybe those energy pulses are translated into areas of varying spacetime density?  I would think something like that could affect the permeability of spacetime and even the performance of electronic devices and nuclear decay rate.  If that is the case, it would probably affect the performance of dielectrics also.  Late night ramblings...

The meteors are out tonight!

https://en.wikipedia.org/wiki/Compressibility

In thermodynamics and fluid mechanics, compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure (or mean stress) change

Cosmo

[astr0144]

Your the 2nd person to post a picture of a Dog that I believe is referred to as Astro....

My Astro or Astr0 connection was intended as either Astronomy/ Astro Physics or astrology related...

If I recall you used to have a image as a Dog which may have been connected to one called Cosmo 

but I assume you connection is Cosmology related ..with may be similar to part of my interests..

I intended to get back to some of your threads..when I can about Gravity...I am distracted with a lot of things at the moment.. and your topic needs deep thought if one is to make any sort of worthy reply..

[lolos]

i recall a beam of light shooting out of a black hole, if i am correct  a black hole has 2 poles that shoot out stuff, but in any case what sort of light is escaping this gravitational pull that even consumes light?
Posted is  a basic google search link http://www.techtimes.com/articles/56234/20150528/hubble-sees-black-hole-spitting-out-light-saber-jet.htm

[COSMO]

i recall a beam of light shooting out of a black hole, if i am correct  a black hole has 2 poles that shoot out stuff, but in any case what sort of light is escaping this gravitational pull that even consumes light?
Posted is  a basic google search link http://www.techtimes.com/articles/56234/20150528/hubble-sees-black-hole-spitting-out-light-saber-jet.htm

That google fella showed me this.  He runs a hell of a web site.  I don't know how he finds the time. 

The new observations, taken by the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope, along with NASA's Rossi X-ray Timing Explorer and a number of optical telescopes, show material moving outward along a spiral channel, as the scientists expected.

These data support the suggestion that twisted magnetic field lines are creating the jet plumes. Material in the center of the galaxy, such as nearby stars and gas, gets pulled in by the black hole's overwhelming gravity and forms a disk orbiting around the core (the material's inertia keeps it spiraling in a disk rather than falling straight into the black hole). The distorted magnetic field lines seem to pull charged particles off the disk and cause them to gush outward at nearly the speed of light.



http://www.space.com/5285-powerful-black-hole-jet-explained.html

Cuzmo

[lolos]

heh