Airbrush

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.

I think you mean galaxies outside our Local Group are red shifted, not stars we see in the night sky. Stars we see in the night sky are all in our galaxy and thus not moving away from us. Right?

That sounds good Mr Skeptic. Maybe just before impact the Slapper splits into 3 rockets that spread the net and rocket past the object at very high closing speed, maybe 20 or 30 miles per second. Even a modest mass at such high velocity will deliver a high kinetic push (KE = 1/2mv^2). The cables may need some elasticity to soften the impact. After contact, ion rockets can continue pushing the object away. The angle of contact would be somewhere between 100 to 180 degrees.

Is everyone else in agreement with Sisyphus? I distinctly remember an episode of The Universe about parallel universes, the Type I parallel universe, or something like that, meant there could be an infinite number of distinct universes inside some kind of hyperspace. What makes you so sure that beyond our visual horizon there is not a lot more? Just like when we used to think our galaxy was the entire universe. If universes bud off of prior universes, or Big Bangs are caused by colliding higher dimensions, then that means a location in space, or hyperspace.

Maybe what we call the universe is only a regional peculiarity. There could be larger scale structures, universes that exist within a "multiverse". There could be individual big bangs separated by unimaginably long distances, such as Trillions or Quadrillions of light years between them. I also don't believe there would be an "outside" to such a multiverse. We don't have ANY evidence for any "nothing". Something seems to permeate all visible space. There are about one hydrogen atom per cubic meter of "empty space" even in the middle of the great voids between superclusters. NOWHERE is there nothing. There are also virtual particles popping in and out of existance everywhere.

You cannot watch electrons running along a wire, but we can witness the effects, electricity. Lot of things we cannot see that exist. We can see dark matter indirectly thru gravitational lensing.

I heard this idea on The Universe, History.com discussions, questions for the universe. Send large numbers of asteroids to impact on Mars to create more mass and heat it up and thus create atmosphere. I think the amount of matter it would take to significantly increase the mass of Mars (by about 50%) would be enough to melt the surface into pools of magma. That would be beyond our technical ability for hundreds or thousands of years. What do you think?

Yes, for lack of a better term, something is causing the outer edges of spiral galaxies to rotate as fast as the central region. That something appears to be several times as massive as all known "normal" (baryonic) matter. And we cannot see it except for gravitational lensing.

Our galaxy contains hundreds of Billions of stars plus unimaginable large mass of gas and dust, and above all dark matter. The galaxy is not held together by a black hole at the center. The mutual gravity of all the stars, dust, gas, and dark matter hold the galaxy together. The black hole at the center of any galaxy is a tiny mass compared to the galaxy. The Milky Way's supermassive black hole is a few million solar masses which is miniscule compared to the much greater mass of the entire galaxy of Billions of stars, gas, dust, and dark matter.

The poster to that physics forum doesn't sound like he knows what he is talking about. Be careful where you get your ideas. The experts are in agreement that the universe is expanding and accelerating in expansion.

What is the world going to do with it's nuclear arsenal? You are right, convert them into defense against short notice impactors (SNI). I have never heard the term "SNI". It distinguishes among NEOs and comets. It means an object that is big enough to cause significant damage on Earth that has been determined IT WILL IMPACT EARTH within perhaps a few years. Then the best you can do is convert as many nuclear missiles as possible to rocket into outer space towards the object and detonate close enough to cause outgasing from the object that can push it like millions of tiny rockets the other way. If enough of the nukes explode properly, it might be enough to save the Earth from a deadly impact.

Nice to know that. Anyone looking for someone to sweep up around the telescopes or cleaning around the computers? I have a BS degree in accounting and could help out with number crunching. If I had a job working on finding NEOs or helping the NEO search folks in other ways, like a gofer, there would be wings on my feet and I would sail to work each day with enthusiasm rather than the tedium of crunching numbers for a restaurant Anyone hiring? Merged post follows: Consecutive posts mergedHere is my idea for a kinetic slapper for short-notice impactors (SNI). For SNI only a direct method stands any chance for success. The kinetic slapper would be a rocket that just before impact splits up into a giant net to soften the impact and thus not break apart the bolide. The kinetic slapper would be built in multitudes and all assigned the same mission: hundreds of them speed towards the SNI at highest closing speeds possible, maybe 10 to 20 miles per second, and just before impact they split apart into a number of sections extending a giant net. The combined effect of hundreds of these kamakazi rockets could be just enough to cause it to skip off the atmosphere and go away.

Thanks for your thoughts and links Arch! This subject fascinates me. I wish I could help work on these, but I am only a bookkeeper for a restaurant.

We have a small, under-funded program to search for NEOs. I only propose we scale it up so we can detect 99% of all NEOs that can cause more than local damage within the next decade. Instead of spending so much on other kinds of space exploration, devote more on planetary defense. If our enemies know we are working on systems to save THEM and their loved ones, that will take SOME of the steam out of their terrorist attacks. We need to develop two kinds of threat mitigation strategies, the direct method, and the indirect method. I have discussed these here before but basically the direct methods are much cheaper and intended for short-notice threats, such as nuclear explosions in close proximity or kinetic impactors. The indirect methods are more costly and take much longer to deploy because they must travel to the object and change course up to 180 degrees to match the speed and direction of the object. Then using techniques such as gravity tractors or laser cannons to slowly nudge it off course over a period of years. We still may do something to control malaria and world hunger, but those are not from NASA's budget. I would like to see fusion power in the near term, but it seems so difficult to accomplish, maintaining a core temperature of over 200 million degrees F. Over the next few decades I think we can do a lot more with wind, solar, nuclear, and perhaps tidal power, along with improved energy efficiency.