http://news.yahoo.com/einsteins-general-relativity-break-under-extreme-conditions-152213544.html

A century ago this year, a young Swiss physicist, who had already revolutionized physics with discoveries about the relationship between space and time, developed a radical new understanding of gravity.

In 1915, Albert Einstein published his general theory of relativity, which described gravity as a fundamental property of space-time. He came up with a set of equations that relate the curvature of space-time to the energy and momentum of the matter and radiation that are present in a particular region.

Today, 100 years later, Einstein's theory of gravitation remains a pillar of modern understanding, and has withstood all the tests that scientists could throw at it. But until recently, it wasn't possible to do experiments to probe the theory under extreme conditions to see whether it breaks down. [6 Weird Facts About Gravity]

Now, scientists have the technology to begin looking for evidence that could reveal physics beyond general relativity.

"To me, it is absolutely amazing how well general relativity has done after 100 years," said Clifford Will, a theoretical physicist at the University of Florida in Gainesville. "What he wrote down is the same thing we use today," Will told Live Science.

A new view of gravity



General relativity describes gravity not as a force, as the physicist Isaac Newton thought of it, but rather as a curvature of space and time due to the mass of objects, Will said. The reason Earth orbits the sun is not because the sun attracts Earth, but instead because the sun warps space-time, he said. (This is a bit like the way a bowling ball on an outstretched blanket would warp the blanket's shape.)

Einstein's theory made some pretty wild predictions, including the possibility of black holes, which would warp space-time to such a degree that nothing inside "not even light" could escape. The theory also provides the foundation for the currently accepted view that the universe is expanding, and also accelerating.

General relativity has been confirmed through numerous observations. Einstein himself famously used the theory to predict the orbital motion of the planet Mercury, which Newton's laws cannot accurately describe. Einstein's theory also predicted that an object that was massive enough could bend light itself, an effect known as gravitational lensing, which astronomers have frequently observed. For example, the effect can be used to find exoplanets, based on slight deviations in the light of a distant object being bent by the star the planet is orbiting.

But while there hasn't been "a shred of evidence" that there's anything wrong with the theory of general relativity, "it's important to test the theory in regimes where it hasn't been tested before," Will told Live Science.

Testing Einstein's theory

General relativity works very well for gravity of ordinary strength, the variety experienced by humans on Earth or by planets as they orbit the sun. But it's never been tested in extremely strong fields, regions that lie at the boundaries of physics. [The 9 Biggest Unsolved Mysteries in Physics]

The best prospect for testing the theory in these realms is to look for ripples in space-time, known as gravitational waves. These can be produced by violent events such as the merging of two massive bodies, such as black holes or extremely dense objects called neutron stars.

These cosmic fireworks would produce only the tiniest blip in space-time. For instance, such an event could alter a seemingly static distance on Earth. If, say, two black holes collided and merged in the Milky Way galaxy, the gravitational waves produced would stretch and compress two objects on Earth that were separated by 3.3 feet (1 meter) by one-thousandth the diameter of an atomic nucleus, Will said.

Yet there are now experiments out there that could potentially detect space-time ripples from these types of events.

"There's a very good chance we will be detecting [gravitational waves] directly in the next couple of years," Will said.

The Laser Interferometer Gravitational-Wave Observatory (LIGO), with facilities near Richland, Washington, and Livingston, Louisiana, uses lasers to detect miniscule distortions in two long, L-shaped detectors. As space-time ripples pass through the detectors, the ripples stretch and compress space, which can change the length of the detector in a way that LIGO can measure.

LIGO began operations in 2002 and has not detected any gravitational waves; in 2010, it went offline for upgrades, and its successor, known as Advanced LIGO, is scheduled to boot up again later this year. A host of other experiments also aim to detect gravitational waves.

Another way to test general relativity in extreme regimes would be to look at the properties of gravitational waves. For example, gravitational waves can be polarized, just like light as it passes through a pair of polarized sunglasses. General relativity makes predictions about this polarization, so "anything that deviates from [these predictions] would be bad" for the theory, Will said.

A unified understanding

If scientists do detect gravitational waves, however, Will expects it will only bolster Einstein's theory. "My opinion is, we're going to keep proving general relativity to be right," he said.

So why bother doing these experiments at all?

One of the most enduring goals of physics is the quest for a theory that unites general relativity, the science of the macroscopic world, and quantum mechanics, the realm of the very small. Yet finding such a theory, known as quantum gravity, may require some modifications to general relativity, Will said.

It's possible that any experiment capable of detecting the effects of quantum gravity would require so much energy as to be practically impossible, Will said. "But you never know -- there may be some strange effect from the quantum world that is tiny but detectable."

Gravity = mass x Pi. Coconut cr�me pi.....

When I first learnt about gravity as a kid at school I didn't believe the teachers when they explained about the force pushing down everything I thought it was all a lie lol

I always thought gravity was the opposite of flying? Well, isn't it?

i look at gravity as a pull, not a push... an electro-magnetic pull comparable to swinging a rock on a string in circles, the sting being gravity, since it effects all mass the same... but it also seems that speed will cancel the effect in certain situations...

umm.. no... flying is actually using the air as a support...

Perhaps coz if it wasn't we would probably all be flying

What do you mean?

It's called the ''Force '' of gravity for this reason

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the faster a body in space flys by another body, the less gravity affects it...

if a meteor is traveling at 40 miles per second, and another the same mass is traveling at 100 miles per hour, the slower one would change course more than the faster one...

thats why they don't worry about fast moving comets/asteroids hitting the earth, it would have to be on a direct path towards us to hit, where a slow moving one can get caught in our gravity easier...

What about G forces that a jet fighter pilot experiences? Such can even black a pilot out & it really feels like a massive push from above as to a pull

yea, same thing... 1g = the normal earth gravity, you can feel it a suped up car when you floor it, the "pulling/pushing" back effect, i guess it just depends on how you look at it...

but thats not really gravity happening, thats your mass not wanting to change speed/direction, the laws of motion...

this a good way to think of it - if the Earth just stopped spinning all at once, most every thats not at the poles would die from being flung at about 200 MPH, things at the equator getting it worse....

No there too. Not electro-magnetic, otherwise the apple that fell on Sir Isaac's head would have been slung off of earth and sucked into the non-existent black hole at the center of the milky way. Apples aren't attracted by magnetism. The rock on a string attached to a stick only works to illustrate gravity on paper. When put into motion the forces acting on the rock are opposing gravity, centripedal and centrifugal force. The string applies centripedal (pulling inwards) overcoming the centrifugal force the mass of the rock swinging out away from the stick and the force of gravity pulling down on the string andthe rock. Magnetism is another force altogether, one that doesn't affect non-ferrous matter.

The hemoglobin in our blood is mostly iron, which is very heavy. Swinging the body looping, drifting etc moves the blood into or out of the brain rapidly and obviously with great force. Our bodies aren't accustomed to pumping blood against more than 2-3g what one would feel when swinging from a tree branch or kayaking. Blood as you well know supplies the brain with oxygen it needs to function properly. Cut off the supply of oxygen to the brain, you pass out or possibly die.

What about G-strings? Or the G-spot?.....

that goes with the push and pull effect...

Not speed. Compound gravitational fields. Think about it like a magnetic field, move another magnet near the field and the field lines (illustrated) warp and interfere. Same thing applies to gravity. It doesn't matter how fast a body ismoving if it's on course to collide, it collides. Shumaker-Levy 9 is a prime example. Jupiter's enormous gravitational pull didn't negate the speed, it changed the speed slowing as it changed course and reaching well above terminal velocity as it broke up before impact. Comets and asteroids aren't easy to break. Oak is extremely hard but opposing forces can cause even the hardest woods to break. Go back to the bowling ball on the blanket, but put three pool balls, a basketball, some baseballs and tennis balls all with their own 'cone' and roll a marble around at 20mph and 20 fps. It'll take the 20mph marble longerto collide with one of the larger bodies and it will travel farther but there's no engine inside it. Gravity is exerting more force on the faster marble, just in a different direction. On the blanket both marbles would hit a larger body, but the blanket would have to be larger than earth for the 20mph marble to orbit on its elliptical course.

Best amusement park ride EVER! until your eyes get sucked out of your head and your skull and chest collapse. Refund?