Airbrush

Carl Sagan was instrumental in getting our position in space engraved in Voyager, so that ETs can find us someday. Recently I heard Michio Kaku suggest that may not be wise. Considering the possibility that ETs could adversely impact us, or eat us or destroy us and take Earth, maybe we should consider not leaking our TV programs to outer space?

The only way neutron star like density material could be found on Earth is to arrive here from outer space, and neutron stars cannot explode and throw pieces of themselves everywhere. Everything else crashes into a neutron star and is crushed to such density, but when neutron stars crash they merge with the energy shown by short gamma ray bursts.

Suppose a planet-sized object gets thrown at high speed away from a supernova. It would be slowed by gas and dust friction somewhat. It's path would be bent by nearby stars, but it would be going too fast to be captured in orbit around any star, unless it slowed down very much.

You are adding a couple of Billion years to the current estimates of the age of the universe. What does the age of the Earth have to do with it? It is not the oldest object, it is only the oldest VISIBLE object ever detected, and not thru visible light either, it is too red-shifted for that.

After the "Dark Ages" ended when the first stars ignited, about 400 Million years after the Big Bang (ATBB), there was a period of about 200 Million years until our recent GRB of 13 Billion years ATBB. Many generations of extremely massive stars could have been born and exploded in less than 10 Million years for each one. Each supernova would put pressure on local gas clouds causing new massive stars to rapidly form. Maybe the recent GRB was not first generation, but a decendant of many previous stars. If we see one GRB there could be thousands of others that were not alligned with Earth, so we would never see those. "Some studies estimate that the very first stars of the universe could have had a much larger mass, perhaps up to 1000 solar masses. Of course, the lifetime of these stars was exceedingly short, but they would have sowed the universe with heavy elements quite early."

This makes sense if the first stars formed about 400 Million years after the Big Bang. This would be among the first stars, a blue, hot supergiant that lived only tens or hundreds of Millions of years. It exploded 600 Million years after the Big Bang, then we saw it 13 Billion years later. Is there any way to know the size of a star that causes a GRB? Merged post follows: Consecutive posts merged I don't think I can ever get that thick-skinned balloon out of my head. Right after posting the above I turned on my radio and the first story on NPR was about this discovery! What a synchronicity.

http://www.astro.ucla.edu/~wright/CosmoCalc.html When I plug 8.2 into where z is supposed to go and click Flat, I get 30.016 Billion LY away currently.

Fascinating discovery! We were discussing most distant object (besides the CMB) which at that time was a gravitationally-lensed galaxy with a red shift of 7.6. But this beats that z = 8.2 means that thing is now over 30 Billion light years away. Could this GRB come from a galaxy, or a solitary Giant? It must have been a short-lived star. The only way we can see that far is by a GRB or gravity lens.

I agree. It is far more likely that a star collapse would be a little off center, and that little bit off-center is all it takes to whip the BH into a very high speed spin.

True that a BH rotating at near relativistic speeds, or I believe they stated a possible limit of 1,000 RPS? What percentage of BH are believed to be rotating at such high speed that they would bulge?

You are asking two questions. The first is essentially "Did the universe have freedom of choice about it's destiny, or was it predetermined at the moment of the Big Bang? I think it was predetermined, based on all pre-existing conditions. But maybe it is possible that during the course of the evolution of a universe, it could take different courses depending upon unforseeable events. Is anything possible? Sure, why not?

Even an object with smaller mass, such as our Moon, is massive enough to compact itself into a sphere. A black hole event horizon must be the most perfect sphere found in nature.

I may be wrong but I think there is a way to collect solar energy from solar cells to charge batteries that can send a pulse to the rockets of the gravity tractor. Kinetic impactors can be sent in numbers, so if one fails others can follow thru with the mission. There must be a way to blunt the impact so you don't break the asteroid into pieces, like a conventional or nuclear explosion just a second before impact, or the probe flattens out to splat against the asteroid. Or rather than a harpoon, a giant net is blasted around the front of the object and the probe swings around the other side attached by an elastic tether to pull on it. After the initial pull the probe will bounce back to the object which could be a problem, so the rebound impact could be avoided by cutting the probe loose after the pull. This would be tricky because the closing speed will be 10 to 20 miles per second. I'm trying to keep the technology as simple as possible. Of course, any of these methods should be tested in advance on non-threatening asteroids.

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.