Airbrush

You make a good point Sherlock about the gravity tractor, which will be effective on lower mass objects. Its' task is so simple that it won't require much coaching from home. It just senses were the object is and adjusts it's distance automatically. It would have to fire its' rockets in small bursts, pointed at angles away from the object, so as not to push the object away by the propulsion system, and also rockets on the opposite side to stop it at the correct distance. It may require a few bursts per hour, or day, or week? over a period of years. What kind of propulsion system can handle that long-term schedule? For giant ones we need a more aggressive method or a combination of different methods. Merged post follows: Consecutive posts merged I just saw a program about this impact on History Channel and they said the mass that vaporized upon impact was about 300,000 tons.

To me it seems like there are 2 basic kinds of asteroid deflection methods. The direct method (kinetic impactor or nuclear explosion in close proximity), and the indirect method (lazer beam or particle cannons, solar sails, gravity tractors, etc). The direct method is short-range (or maybe even long-range) cheaper and quicker, a possible last resort to deal with short-notice asteroids. The indirect methods are preferable, but they cost more and take much, much more time, not only to develop but also to reach its' more distant destination. I like the simplicity of the kinetic impactor, especially if you can hit the object years before it comes near Earth. It wouldn't matter where you hit the object or even if you break it into pieces, because even a small change in course will cause it, and all the pieces of it, to miss Earth by a wide margin. With the direct method all you need is the mass and inertia of the rocket on an intercepting path at high closing speed, but the indirect method requires acceleration towards the asteroid, then a major course change to reverse direction to match the speed and path of the asteroid so as to fly alongside it, or gently "dock" with it to attach devices, or hover at a safe distance and do it's thing. I further propose that the indirect method spacecraft be multi-purpose. We need to test the object to find out its' composition and how solid it is, report back home, then we select from its' "quiver" from a number of on-board deflection techniques appropriate to the particular bolide.

Then the Kepler field of vision is about 20 X 20 moons. I wonder what depth of field it covers? Of the 100,000 candidate stars, what is the distant to the closest? And the furthest? Thanks for the link Arch. That article gives a good idea of the Kepler field of vision, roughly the size of your open hand at arm's length, and Hubble sees an area about the size of a grain of sand at arm's length.

Thanks for the Kepler update Martin. For us city slickers who don't know how big the Big Dipper is in the sky. Can anyone describe how large 10 degrees by 10 degrees is in the sky using full moon diameters? When I examined the hi res photo of the field of stars I was surprised that there was such a high density of stars in a patch of sky. Next we want to see a wall-sized poster of that field of stars.

Since they suspect binary neutron stars merging to cause the short gamma ray bursts (GRB), then could binary black holes produce the same effect? Each black hole drags an accretion disk into the other black hole. Could that energy released be comparable to neutron stars merging? From wiki: "Most GRBs appear to be collimated emissions caused by the collapse of the core of a rapidly rotating, high-mass star into a black hole. A subclass of GRBs (the "short" bursts) appear to originate from a different process, the leading theory being the merger of neutron stars orbiting in a binary system."

How can there be both a big freeze and big crunch? Seems like a big freeze means even after Trillions of years gravity was not sufficient to overcome dark energy, and expansion continues "over the hill" and never stops. Either big freeze or big rip.

The original question, simply stated, is "do black holes have magnetic fields?" Good question, I don't know. Magnetars are neutron stars with fantastic magnetic fields. Black holes have mass, spin, and charge. Does any of that imply magnetic fields? http://en.wikipedia.org/wiki/Magnetar

I think the term "ID" or "intelligent design" is vague enough that people can argue about it without having the exact same meaning in mind. Which means they are just arguing past each other. To me ID simply means the aggregate of all physical laws and forces and the chemical properties of matter that allow life to evolve. It is a neat coincidence that the Earth has such a large moon that is massive enough to stabilize the Earth's axis of rotation, without which intelligent life could probably not exist on Earth.

Exactly my point! The dirt is deficient in minerals, so plants are deficient in minerals, and animals that eat the plants are deficient in minerals. And I haven't even mentioned vitamins and other nutrients yet.

How difficult would it be to test the mineral supplement for the minerals listed on the label? Has it been done? I believe there is an implicit conspiracy between the medical profession and pharmaceutical companies. People are supposed to go to the doctor when they are not well so the doctor can prescribe drugs to mask the symptoms. The only way to correct your health problem is eating correctly and exercising. What if Joel Wallach is right? In this age of mass production, all foods are becoming more mineral deficient over time with soil mineral depletion, because not much nutrition comes from petrochemical fertilizers. More attention is given to the nutritional requirements of cattle than humans.

I took a look at those paradoxes and I honestly don't understand them. Would you care to explain? What does it mean that the expansion of space is unobservable? Many science facts are unobservable. You cannot observe electrons running along a copper wire. Some science facts are proven by other means.

That is an optical illusion. Light moves so fast that it is hard to say if it is in two places at once. But let us know if you ever notice the real deal.

Does anyone have an opinion of the subject of colloidal liquid minerals? The famous or infamous Joel Wallach was promoting liquid minerals from his web site. He is known for his tape recording "Dead Doctors Don't Lie". "There are 90 nutrients essential to human health. A common recommendation made by most medical doctors is that in order to get all the nutrients necessary to maintain health you must, on a daily basis, eat food from each of the four basic food groups. Dr. Joel Wallach challenges this belief and highlights the reasons why it is practically impossible to get all the nutrients necessary to achieve and maintain opitimal health by eating food from the four food groups. Therefore you must supplement!" He may be a con man, and he makes a lot of incredible claims, but I believe many health problems come from nutrient deficiency. Mass produced agriculture is short of the nutrients from chemical fertilizers. If colloidal minerals does indeed contain 60 or more minerals that may be valuable to the body, then why not?

The light that left galaxies Millions of years ago tell us the universe WAS expanding. The light that left galaxies Billions of years ago also tell us the universe WAS expanding. The light from galaxies everywhere in between (Millions and Billions of years ago) tell us the SAME thing. You propose a departure from a long-standing trend and nothing to support that. I base my opinion on the opinion of the experts. They know better and I trust their judgment. If a scientist came up with evidence to the contrary, supporting your proposition, it would be VERY exciting among most scientists who would get busy trying to reconcile the new evidence.

Interesting explanation SH3RLOCK. I suppose a cold dead star would be solid all the way to the core. That is hard to visualize, but it must be so. As for where do they find hydrogen for a fusion reactor? Space will always be full of hydrogen gas and other kinds of dust that never gets compacted into stars. Not all matter gets pulled together into stars. They would need to sweep thru space collecting free hydrogen, and that supply of free hydrogen atoms is everywhere in the universe, nearly limitless. I believe that there is more gas and dust in the universe than all the stars, black holes, planets, asteroid, and comets combined.

Darkness is merely the absence of light, but if you set up a lazor on the Moon, focused on a sensor here on Earth, and turned it on and off at regular intervals, let's say three seconds on, three seconds off, the darkness between the light pulses would arrive at exactly the same speed as the light. Darkness is an aspect of light, so it follows the rules of light.

I find it hard to believe that a dead star will ever become cool all the way to its' core. There will always be pressure, and therefore heat energy. That is why mines get hotter the deeper they dig. Intelligent beings that are still living Trillions of years from now could dig tunnels into dead stars to mine the heat energy. Or they could build a fusion reactor that never cools. All they need to do is add a little hydrogen to it now and then. E=mc^2. Energy could always be extracted from matter, as long as there is matter in the universe.

I agree. If astronomers can get together to decide Pluto is no longer a planet, but rather a "dwarf planet" then why can't cosmologists get together and rename the Big Bang? It would be a newsworthy story. I don't know a more appropriate term, but how about "Cosmic Expansion"?

Does not gravity itself generate heat energy just from the pressure? How can that heat pressure ever decay to a non-energetic state? After all the red dwarf stars have burned out and cool, there will still be places deep inside massive objects that will eternally create heat from pressure.

It's like fighting fire with fire. You intentionally cause a dormant volcano to erupt by digging tunnels into the magma chamber, so it will let off pressure and not explode. This is done by a series of explosions burrowing down creating a magma channel. All the while some master the fine art of digging tunnels others are studying the composition and formation of our greatest challenge for survival, Yellowstone. Detailed maps must be created to know precisely where and how to tunnel. Yet they must first be sure they won't accidentally set off the Big eruption. That is our ultimate challenge.

Words used in titles of books should not be taken so seriously. Michio, like Carl Sagan before him, is good at presenting science to a general audience. "Impossible" in this context only means currently impossible or improbable in the near future, but in the more distant future that could change.

If there is evidence for an intentional shortage of health care workers, to inflate their wages, that would be interesting news! Let's hear it.

We can measure expansion all along a continuum from near to far. Over that range of over 10 Billion years there WAS expansion of various consistent rates including inflated rates. So probably expansion continues.

The question is how fast can we progress at investigating smaller volcanos first, as a poster above proposed? They would need to practice ways of blasting huge tunnels, using both conventional and small nuclear explosives, in small volcanos to let magma flow into a safe area which would be totally covered by volcanic material. But they need to be ever mindful of the fact they could accidentally trigger a disaster! If we don't do anything, then when the day comes, either next year or after another ten thousand years, Yellowstone WILL go off big time, and the USA will be laid to waste and a long-term nuclear winter WILL cause mass extinctions, maybe even humans. Merged post follows: Consecutive posts mergedI'm no geologist, but it seems to me it could be possible to dig giant tunnels into small volcanos to create a pressure valve. Whenever magma builds up the volcano will erupt, but in a controlled fashion. It would look like a giant gyser of magma that periodically blasts like a cannon shot out of an artificial volcanic crater, whenever the pressure goes up. There would be heat energy collection stations all around the magma pile that would turn steam turbines, generating clean electricity.

That sounds right to me. Good question. Is it only because it is improbable for something that is seen to be expanding at an increasing rate to abruptly slow down, stop, and reverse? That reversing process seems unlikely, and would take a long, long time. It will be interesting to hear comments.