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strawberryrain:

mothernaturenetwork:

What the universe has in common with ‘Doctor Who’The universe may be bigger on the inside, like the Doctor’s TARDIS.

HEY BT

strawberryrain:

mothernaturenetwork:

What the universe has in common with ‘Doctor Who’
The universe may be bigger on the inside, like the Doctor’s TARDIS.

HEY BT

quantumaniac:

Black Holes: Everything You Think You Know Is Wrong
Image: Hot iron gas rides a wave of space-time around a black hole in this computer image taken from a Rossi X-ray Timing Explorer observation. Credit: NASA
If most people know one thing about black holes, they probably know that nothing can escape from them, not even light.
Yet this most basic tenet about black holes has actually been disproven by the theory of quantum mechanics, explains theoretical physicist Edward Witten of the Institute for Advanced Study in Princeton, NJ, in an essay published online today (Aug. 2) in the journal Science.
Black holes, in the classical picture of physics, are incredibly dense objects where space and time are so warped that nothing can escape from their gravitational grasp. In another essay in the same issue of Science, theoretical physicist Kip Thorne of Caltech describes them as “objects made wholly and solely from curved spacetime.”
Yet this basic picture appears to contradict the laws of quantum mechanics, which govern the universe’s tiniest elements.
“What you get from classical general relativity, and also what everyone understands about a black hole, is that it can absorb anything that comes near, but it can’t emit anything. But quantum mechanics doesn’t allow such an object to exist,” Witten said in this week’s Science podcast.
In quantum mechanics, if a reaction is possible, the opposite reaction is also possible, Witten explained. Processes should be reversible. Thus, if a person can be swallowed by a black hole to create a slightly heavier black hole, a heavy black hole should be able to spit out a person and become a slightly lighter black hole. Yet nothing is supposed to escape from black holes.
To solve the dilemma, physicists looked to the idea of entropy, a measurement of disorder or randomness. The laws of thermodynamics state that in the macroscopic world, it’s impossible to reduce the entropy of the universe — it can only increase. If a person were to fall into a black hole, entropy would increase. If the person were to pop back out of it, the universal entropy tally would go down. For the same reason, water can spill out of a cup onto the floor, but it won’t flow from the floor into a cup.
This principle seems to explain why the process of matter falling into a black hole cannot be reversed, yet it only applies on a macroscopic level.
Continue..

quantumaniac:

Black Holes: Everything You Think You Know Is Wrong

Image: Hot iron gas rides a wave of space-time around a black hole in this computer image taken from a Rossi X-ray Timing Explorer observation. Credit: NASA

If most people know one thing about black holes, they probably know that nothing can escape from them, not even light.

Yet this most basic tenet about black holes has actually been disproven by the theory of quantum mechanics, explains theoretical physicist Edward Witten of the Institute for Advanced Study in Princeton, NJ, in an essay published online today (Aug. 2) in the journal Science.

Black holes, in the classical picture of physics, are incredibly dense objects where space and time are so warped that nothing can escape from their gravitational grasp. In another essay in the same issue of Science, theoretical physicist Kip Thorne of Caltech describes them as “objects made wholly and solely from curved spacetime.”

Yet this basic picture appears to contradict the laws of quantum mechanics, which govern the universe’s tiniest elements.

“What you get from classical general relativity, and also what everyone understands about a black hole, is that it can absorb anything that comes near, but it can’t emit anything. But quantum mechanics doesn’t allow such an object to exist,” Witten said in this week’s Science podcast.

In quantum mechanics, if a reaction is possible, the opposite reaction is also possible, Witten explained. Processes should be reversible. Thus, if a person can be swallowed by a black hole to create a slightly heavier black hole, a heavy black hole should be able to spit out a person and become a slightly lighter black hole. Yet nothing is supposed to escape from black holes.

To solve the dilemma, physicists looked to the idea of entropy, a measurement of disorder or randomness. The laws of thermodynamics state that in the macroscopic world, it’s impossible to reduce the entropy of the universe — it can only increase. If a person were to fall into a black hole, entropy would increase. If the person were to pop back out of it, the universal entropy tally would go down. For the same reason, water can spill out of a cup onto the floor, but it won’t flow from the floor into a cup.

This principle seems to explain why the process of matter falling into a black hole cannot be reversed, yet it only applies on a macroscopic level.

Continue..

expose-the-light:

What if we had a planet instead of a Moon?

Our moon is a pretty big object. It’s big enough to be a respectable planet in its own right, if it were orbiting the sun instead of the Earth. (Actually, it is orbiting the sun in a nearly perfectly circular orbit, that the Earth only slightly perturbs… but that’s a topic for another day.) The Moon is a quarter the diameter of the Earth. Only Pluto has a satellite that is larger, in proportion to the size of the planet it orbits.

But what if the Moon were size of Mars, instead? It would like the picture above. Check out how some of the other planets of the Solar System would look in our sky, if they took the Moon’s place.

At a distance of about 240,000 miles, the Moon occupies a space in the night sky about half a degree wide. By sheer coincidence, this is almost exactly the same size the sun appears, which is why we occasionally get total solar eclipses. (We don’t get a total eclipse every time the Moon passes in front of the sun because the Moon is sometimes a little closer to the Earth and sometimes a little further away, so it will cover more or less of the sun during any eclipse.)

But it’s interesting to imagine what the night sky might look like if one of the Solar System’s planets were to replace our moon. (We’d have to ignore things like tides and gravitation, but that’s the advantage of doing things in the mind’s eye.) So what would we see if we were to replace the moon with Mars? The red planet is almost exactly twice the size of the Moon, so it would appear twice as big in the Earth’s sky. It would be easy to see with the naked eye details on the surface of the planet that were previously visible only through telescopes. You could watch the ice caps grow and shrink during the changing seasons, see dust storms form and move across the planet and make out features like Vallis Marineris and Olympus Mons.

Read More

quantumaniac:

Chemistry On Mars

The Mars Science Laboratory will be seeking clues to the planetary puzzle about life on Mars, the Curiosity rover is one of the best-outfitted chemistry missions ever. Scientists say Curiosity is the next best thing to launching a team of trained chemists to Mars’ surface.

“The Mars Science Laboratory mission has the goal of understanding whether its landing site on Mars was ever a habitable environment, a place that could have supported microbial life,” says MSL Deputy Project Scientist, Ashwin Vasavada, who provides a look “under the hood” in this informative video from the American Chemical Society.

“Curiosity is really a geochemical experiment, and a whole laboratory of chemical equipment is on the rover,” says Vasavada. “It will drill into rocks, and analyze material from those rocks with sophisticated instruments.”

Curiosity will drive around the landing site at Gale Crater and sample the soil, layer by layer, to piece together the history of Mars, trying to determine if and when the planet went from a wetter, warmer world to its current cold and dry conditions.

The payload includes mast-mounted instruments to survey the surroundings and assess potential sampling targets from a distance, and there are also instruments on Curiosity’s robotic arm for close-up inspections. Laboratory instruments inside the rover will analyze samples from rocks, soils and the atmosphere.

The two instruments on the mast are a high-definition imaging system, and a laser-equipped, spectrum-reading camera called ChemCam that can hit a rock with a special laser beam, and using Laser Induced Breakdown Spectroscopy, can observe the light emitted from the laser’s spark and analyze it with the spectrometer to understand the chemical composition of the soil and rock on Mars.

quantumaniac:

Our Incredible Planet

These incredible images of the planet Earth show it at its most striking and dramatic, and are more akin to those normally taken from Neptune, Mars or Pluto.

The alien-looking images come from a variety of locations across the globe including the White Desert in Egypt, Monument Valley in the U.S., and the Chocolate Hills of Bohol Island in the Philippines. The images include shots of salt plains, rock formations, geysers, sand dunes, mud playas, lava shelves and deserts.

quantumaniac:

Major Telescopes and their Primary Parts


blue is where the science happens

quantumaniac:

Major Telescopes and their Primary Parts

blue is where the science happens

quantumaniac:

Solar System Symbols

quantumaniac:

Solar System Symbols

quantumaniac:

Klein Quartic

quantumaniac:

Klein Quartic

So, what happens at the “edge of the universe?”

oceanastronaut:

brokentripod:

If we assume that the universe is a finite size and is expanding into nothingness or a vacuum..

Then what is happening at the edge between the particles at the edge of the universe and the vacuum just beyond there?

From Wikipedia: “A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in practice.”

So at the edge of the universe is a perfect vacuum, because no matter has reached it yet?

And if the edge of the universe is being pulled outwards really, really fast, photons of light would still surpass this line. And they’d just sort of go out of the bounds of the edge of the universe into a place where there is nothing?

I don’t know.

Huh, I’m not entirely sure.

Granted I don’t have any solid science to back me up, but I doubt there’d be an edge. The universe seems to dislike edges, sharp points, and things like that simply because at some level when you graph the derivative of such a distribution, it leads to infinite or zero energy being required. Which is a no-no, as I’m sure you know. 

Additionally, your idea about photons was something I was about to mention before I saw that you already brought it up. Technically, for there to be a perfect vacuum “beyond” the universe, the universe would have to be expanding at or faster than the speed of light, since any photons that moved beyond the “edge” of the universe would count as matter (?) (or at least ‘stuff’) and push the “edge” that much farther.

It’s my impression that the universe is expanding quite rapidly, but not that rapidly, thus I’d have to posit an alternative:

Perhaps the universe is spherical in more than one sense? If it were curved at higher dimensions, then there would be no edges for us to reach. Kinda like a Klein Bottle

That would be the most reasonable explanation to me: that there is no edge, no inside, no outside. Then you completely avoid any ideas of perfect vacuums, infinite energy drops (or spikes, depending on which direction you’re measuring), or light-speed universe volume increases!

Just in case anyone was wondering why I tagged it #oceanastronaut. It’s not because I’m aware of an astronaut that is really smart and located in the ocean, but because he is Evan and probably still an astronaut, just not in the ocean (and he doesn’t know he’s an astronaut yet).

The Klein bottle idea is interesting, as that does remove the such stuff I mentioned. But it seems like light would travel so far in the Klein bottle that we’d be able to see ourselves? (Eventually, at least?) Unless the Klein bottle idea is expanding at a rate faster than the speed of light. (And then there’s that whole “but what is the Klein bottle located in?”)

The reason I mentioned photons is because of the idea that: “the photon has no rest mass; this allows forinteractions at long distances.”

I don’t know very much about the big bang or conversations on the expansion or contraction of the size of the universe, or the conversations about the universe being infinite or finite, unfortunately. I do recall hearing my honors physics teacher in high school suggesting that it is infinite and expanding at an increasing rate.

So, what happens at the “edge of the universe?”

If we assume that the universe is a finite size and is expanding into nothingness or a vacuum..

Then what is happening at the edge between the particles at the edge of the universe and the vacuum just beyond there?

From Wikipedia: “A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in practice.”

So at the edge of the universe is a perfect vacuum, because no matter has reached it yet?

And if the edge of the universe is being pulled outwards really, really fast, photons of light would still surpass this line. And they’d just sort of go out of the bounds of the edge of the universe into a place where there is nothing?

I don’t know.

Actual Definitions of Commonly Confused Mathematical Terms

quantumaniac:

CLEARLY: I don’t want to write down all the in-between steps.

TRIVIAL: If I have to show you how to do this, you’re in the wrong class.

OBVIOUSLY: I hope you weren’t sleeping when we discussed this earlier, because I refuse to repeat it.

RECALL: I shouldn’t have to tell you this, but for those of you who erase your memory tapes after every test, here it is again.

WITHOUT LOSS OF GENERALITY: I’m not about to do all the possible cases, so I’ll do one and let you figure out the rest.

ONE MAY SHOW: One did, his name was Gauss.

IT IS WELL KNOWN: See “Mathematische Zeitschrift”, vol XXXVI, 1892.

CHECK FOR YOURSELF: This is the boring part of the proof, so you can do it on your own time.

SKETCH OF A PROOF: I couldn’t verify the details, so I’ll break it down into parts I couldn’t prove.

FINALLY: Only ten more steps to go.

PROOF OMITTED: Trust me, it’s true.