Airbrush

The Russian said no nukes will be used but they will send a "special purpose" spacecraft. Apophis will fly by in 2029, so we have 19 years to plan and deploy something. It will be a great chance to experiment with methods of deflection. It is 885 feet in diameter. If it did impact Earth how fast will it be moving? depends upon the angle? what kind of kinetic energy would that impact be in megatons? Will it explode in the air? Wikipedia on Apophis: "As of October 7, 2009, the impact probability for April 13, 2036, is calculated as 1 in 250,000. An additional impact date in 2037 was also identified; the impact probability for that encounter is calculated as 1 in 12.3 million. "Many scientists agree that Apophis warrants closer scrutiny. To that end, in February 2008 the Planetary Society awarded $50,000 in prize money to companies and students who submitted designs for space probes that would put a tracking device on or near the asteroid. Several other groups have studied or plan to study missions to Apophis."

I'm glad someone is thinking about getting a mission going. What if they push the asteroid the wrong way and cause an Earth impact? Why don't they trust the NASA estimate of such low probability for impact? OK, better to be safe than permanently sorry.

I don't understand this very well but does this suggest that intergallactic space is more dense than space within a galaxy? Also I recall that estimates of the density of matter in the middle of the great voids between superclusters was about one atom per cubic meter. Could it be that the average density of matter in the entire universe, including all stars, black holes, planets, etc, is approximately the same as the average density in the middle of the great voids? And the reason being is that space is so vast, that no matter how much matter there is, the average density of the entire universe is insignificantly greater than the density of empty intergallactic space?

Interesting stuff, but the math is beyond me. Anyone want to explain what he is saying in 50 words or less? It would seem like the effect of dark energy is opposite to matter, so call it "negative mass". Why not? And not to be confused with antimatter.

That's what I was thinking teranko, that dark matter occupies higher dimensions of M-Brane Theory. It is a "Ghost Gravity" that leeks thru to our 3 spatial dimensions. It can never be detected in these 3 dimensions. I don't know how dark energy can be explained this way. You want to elaborate? Dark energy is simply an underlying repulsive property of empty (or nearly empty) space. It has such a weak force that it is effective only over the vast distances between superclusters of galaxies. Mlich, the difference between dark matter and dark energy is one is about matter and the other energy that acts on matter. I don't know what the equivalence of matter and energy has to do with it. You care to elaborate?

Fascinating pictures! Thanks for sharing. What a wide range of terrain. Are those pictures enhanced or is that very much what we would see if we were there?

"...What about light at the extreme edge of this singularity, what would be holding it back ?" Because of cosmic inflation, maybe there is no extreme "edge". Or that is long gone, beyond our visual horizon. This kind of stuff is very strange and hard to imagine.

And thanks to iNow for the following cool Einstein quote about space-time needs matter as a pre-condition: "People before me believed that if all the matter in the universe were removed, only space and time would exist. My theory proves that space and time would disappear along with matter." Interesting that he called it "space and time" and not "space-time". When did he start calling it "space-time"? How about using the word "space" for the condition preceeding matter. Space-time is post-matter. So space is timeless, but space-time begins with a Big Bang.

Could dark matter be "ghost gravity" of an overlapping higher dimension? It could never be detected other than its' gravitational effects. Thanks for the cern link moth. Interesting stuff.

"My theory proves that space and time would disappear along with matter." ~Einstein So it is correct to say that space-time would not exist without matter.

How about space-time is a seething expanse of virtual particles popping in and out of existence constantly? Is it correct to say that except for the occasional hydrogen atoms in otherwise empty space, space-time is nothing?

The word "nothing" is too extreme for my comfort. He used the term rhetorically. He should have said that something can come from "zero total energy". Or at least he should have explained in advance what he meant by "nothing". Scientists are supposed to be precise. Nothing is an absolute term, and I don't believe it ever existed. I am also a novice at cosmology, but I got a lot from his talk. Maybe because he said things like "something always comes from nothing". Hehehe.

Can something come from nothing? What exactly IS "nothing"? I don't believe "nothing" is as simple as the word makes it sound.

That was a wonderful talk. Thanks for sharing. "Everything that happens has [VERY] small probablity." Yes Moth, near the end he said if a new universe began, from the outside it would appear to be as a black hole. Very interesting. Anyone care to explain? How massive a black hole? Recently I posted that "nothing" is so improbable. All we can see is something. In a flat universe, with total energy of zero, something will always come from nothing, especially if something has infinite time and space to pop out of nothing.

Anyone know when the Kepler Mission will start reporting results?

For some interesting info about Jupiter's atmosphere, and how it gradually becomes more dense, hot, and liquid, as you go deeper into the atmosphere, you should see The Universe episode about "Liquids in the Universe" on the History Channel. That was fascinating. At some point it gets so dense and hot that it is hotter than the surface of the Sun and gradually transitions from dense gas to hot liquid hydrogen. When you think of liquid hydrogen you would think very very cold, but Jupiter is different. The pressure is so very great that hydrogen can be hot AND liquid.

Cool info about the Shiva Impact. Thanks for sharing. Why have I never heard of that? It's certainly never been on the History Channel or the popular media.

I agree with you about absolute time. We will probably never know about the "time" or anything else before our BB. "The BB was the beginning of the expansion of EVERYTHING...it didn't occur in a localized area of spacetime. Spacetime grew with it.....that's if I understand the BB model correctly." It was the beginning of everything visible to us. We don't know anything about structures beyond our visual horizon. There could well be regions far beyond the edge of our BB that are totally empty of atoms. There could be an infinite number of finite BBs contained in infinite space. Or beyond our visual horizon matter is doing something else like antimatter, or stuff we never even imagined.

You are assuming that the Big Bang (BB) is all there is, and there could be no other BBs, before or after ours. We know nothing about before OUR BB. The Big Bang could just be another temporary condition of localized space-time. At one time the Earth was the entire universe, then the galaxy, now the observable universe is supposed to be "all there is".

Like Spyman said, "nothing" is hardly the word to use. What may appear to be nothing to us now, will probably prove to be infinitely complex, just like everything else. Before the Big Bang there certainly existed a profound potentiality for existence as we know it, and that ain't nuthin'.

The cosmo constant does not affect objects down to the molecular level. It doesn't even affect stars within a galaxy. If the gravity within a galaxy is enough to overcome the cosmo constant, then certainly electromagnetic forces would overcome the cosmo constant a Trillion Trillion Trillion times over. And the nuclear forces are WAY more powerful.

Interesting info Mr. Spyman. So the ultimate fate of 97% of the stars in our galaxy, or perhaps all galaxies, is the white dwarf stage, to slowly cool into a black dwarf over trillions of years, the other 3% collapse into neutron stars or black holes?

Yes, they cannot detect any such "thing" being added as space-time expands. Have you heard if the average density of matter in the observable universe is about one atom per cubic meter? Or is that the density of space in the middle of the great voids between supercluster? Maybe the more rarified space is, the more dark energy. Yes, you are looking for something that does not exist, because that space-time has not yet been activated as the expansion of space.

Interesting about how stars lose mass over time. How much mass can a star shed before it dies by nova or supernova? Our sun will just expand into a red giant then shrink back into a white dwarf? In the process how much mass will the sun shed, both during its' lifetime, and upon death? Did Hawking say that stars will eventually shed so much mass that they will drift apart, no longer bound? What about dark matter, will that also dissolve? If dark matter does not evaporate, then the galaxy will remain gravitationally bound. 15 cm per year? Wow. Are the other planets also spinning out? How do you think we can change the Earth's orbit?

No, not everything is moving apart. The moon is moving away from Earth at a miniscule rate, but where did you hear all the planets are moving away from the Sun? I don't believe that. Also ALL the stars in our galaxy are gravitationaly bound and NOT moving apart, except for minor movements of density in the spiral arms. Galaxies are tightly bound together with very few exceptions of a very few stars getting flung outward because of interaction in binary systems of several stars. Andromeda is actually speeding toward us. Our entire local group of galaxies are also bound together permanently. Even clusters of galaxies are bound together. No, not everything is moving apart, except for superclusters of galaxies.