Airbrush

Yes, we are the remnants of the Milky Way that was not sucked into our central black hole. Even though that black hole is a few Million solar masses, it is a small mass compared to the entire galaxy of hundreds of Billions of solar masses. That central black hole only sucked up matter in the central region and had very little affect on the entire galaxy.

If a photon has zero mass, then how can it have momentum? Zero times anything is zero.

On the topic of "Asteroid Impact Avoidance" under "Collision Avoidance Strategies" the first two listed options are nuclear devices and kinetic impactors, which could be effective against the more solid objects of some sizes. What will deliver more energy to move the object a nuclear bomb or a kinetic impactor of the same mass? A series of nuclear explosions would take advantage of the large stockpiles of thousands of nuclear weapons, and put them to work for a worthy cause, "saving the world". Since Obama and the Russians have agreed to reducing nuclear arsenals by 30%, those bombs could be used for missions to NEOs. From Wikipedia: http://en.wikipedia.org/wiki/Asteroid_impact_avoidance#Collision_avoidance_strategies "Detonating an explosive nuclear device above the surface (or on the surface or beneath it) of an NEO would be one option, with the blast vaporizing part of the surface of the object and nudging it off course with the reaction. This is a form of nuclear pulse propulsion. Even if not completely vaporized, the resulting reduction of mass from the blast combined with the radiation blast and rocket exhaust effect from ejecta could produce positive results. Another proposed solution is to detonate a series of smaller nuclear devices alongside the asteroid, far enough away as not to fracture the object. Providing this was done far enough in advance, the relatively small forces from any number of nuclear blasts could be enough to alter the object's trajectory enough to avoid an impact. This is a form of nuclear pulse propulsion. The 1964 book Islands in Space, calculates the nuclear megatonnage necessary for several deflection scenarios. The hurling of a massive object at the NEO, such as a spacecraft or another near-earth object, is another violent possibility. A small asteroid or large mass in a stable high-Earth orbit would have tremendous kinetic energy stored up. With the addition of some thrust from mounted rockets (plasma or otherwise), it could be used like a stone from a slingshot to deflect the incoming threat. An alternative means of deflecting an asteroid is to attempt to directly alter its momentum by sending a spacecraft to collide with the asteroid. The European Space Agency is already studying the preliminary design of a space mission able to demonstrate this futuristic technology. The mission, named Don Quijote, is the first real asteroid deflection mission ever designed. In the case of 99942 Apophis it has been demonstrated by ESA's Advanced Concepts Team that deflection could be achieved by sending a simple spacecraft weighing less than one ton to impact against the asteroid. During a trade-off study one of the leading researchers argued that a strategy called 'kinetic impactor deflection' was more efficient than others."

Interesting point Mr. Skeptic. Then the question is what effect will this plasma have on asteroids of various compositions, from various distances? I would like to find out. Sherlock, you make an excellent point about from what angle to set off an explosion, relative to the asteroid's rotation. Aligned with it's rotational axis will give the most push, but is that the ideal direction? These are all questions that can only be answered by trying it. My wiki research led me to this story about a proposed problem for experts at MIT in 1967 to prevent Icarus from impacting Earth in 15 months. Their decision was a series of nuclear devices. But hope for success was minimal. http://www.thespacereview.com/article/175/1 "...A slow rendezvous, or even a soft landing, was totally out of the question: Icarus would be moving too fast for a spacecraft to reach it and then reverse direction for a rendezvous....The only option was a fast intercept—fly out to Icarus and detonate a bomb near the surface to change its course. "What the group decided to do was to take six Saturn V rockets then in production, and with only minimal modifications to their payloads use them to carry smaller bombs to Icarus. The first launch would have to take place by April 1968, only a year away, and five more launches would have to follow at two-week increments. "Despite studying several asteroids up close with robotic probes and even landing on one with the NEAR spacecraft, planetary scientists are still unsure how they’re composed. One theory, known as the “rubble pile,” is that many asteroids are not really rocks, but bundles of rocks and dust. Hitting one with a nuclear explosion might accomplish little, as it would absorb the blast and not move very much. Compare trying to push a rock across the floor with one finger with pushing a pile of peanuts, or sand, across the ground with a finger." If it turns out to be a rubble pile, then all you need to do is penetrate to the center of the pile and explode the nuke. Fragments will fly in all directions and you will reduce the amount of material that makes it all the way to Earth. That was over 40 years ago, I would like to see an updated scenario using modern technology.

Thanks for your help Moontanman. Since I want to conduct a larger number of experiments, send 20 nuclear devices of half a megaton each. That is a total of 10 megatons, so the payload, using 6mt/2200lbs, 10mt would weigh less than two US tons (sorry as an American I'm not familiar with metric tons). The idea is to probe, survey, and test the asteroid to find out how solid it is. Then set off a half megaton device from a great distance and measure the effect. Then you set them off closer and closer. Nuclear devices, which are already paid for and setting in an inventory, is the most efficient, thrifty, and time-saving method of any other you can name. The answer to asteroid threat mitigation is ALL THE ABOVE (gravity tractors and attaching rockets, which will take decades longer, kinetic impactors, etc.) by many different means. However nukes should be forward, center, something already available. All you need to build is the robotic rocket to take them out there. Paul, there is no shock wave in the near-vacuum of space. All you can do with a nuclear explosion is heat one side of the asteroid to cause outgassing which will push like thousands of tiny rocket engines.

Nukes ARE cheap. We already paid for them. Sending a gravity tractor, or rockets to attach to an asteroid, will be heavy payloads, maybe heavier than a few nuclear devices. How much does a one megaton nuke weigh? * My guess is the weight of the actual nuclear device(s) will be small in comparison to the fuel needed to get to the asteroid belt, then change course dramatically, slow down, and match the speed of the asteroid, so it will fly along side. *"The W54 warhead used on the Davy Crockett weighed just 51 pounds and was the smallest and lightest fission bomb (implosion type) ever deployed by the United States, with a variable explosive yield of 0.01 kilotons (equivalent to 10 tons of TNT" http://www.brookings.edu/projects/archive/nucweapons/davyc.aspx At that ratio, a one megaton would weigh about 5,100 lbs. But that was 50 year old technology (1961). I think a modern one megaton does not weigh that much. Maybe 500 lbs. It does not need a heavy, hardened steel casing, like an IBM, to penetrate the atmosphere at high re-entry speed. Anyone know? What does Wiki say? "The Peacekeeper was a MIRV missile; the MX could carry up to 10 re-entry vehicles, each armed with a 300-kiloton W87 warhead/MK-21 RVs (twenty times the power of the bomb dropped on Hiroshima during World War II." http://en.wikipedia.org/wiki/MX_missile There you have it. The missile carried 10 nukes of 300 kilotons each (3 megatons). That did not need the Saturn V rocket to launch it. Not too heavy.

Mr Skeptic: "No, we most definitely do not want to test that near earth. One is the issue of the EMP from the nuke. Another is that if you deflect it near earth, it is much more likely to hit the earth. It would change the orbit but the orbit would still have to pass through that point (ie, where it is now), and if that point is near earth the new orbit could bring it on a collision course." OK then, we might start with NEOs that are so far away that even if we blunder the results will not be disaster. I like Toastywombel's ideas, but those will take much longer, and cost a lot more than simply using what we already have. Nukes are a cheap and efficient way to deliver a powerful punch to a far away destination. And we already have them. Now all you have to do is build the robotic probes that will carry out the missions. The nuke push has the great advantage of simplicity. Of course, the robotic probe will stand off at a safe distance watching what happens and measuring the effect of the blast.

Because of treaties against nukes in space, there would have to be some kind of joint mission, including USA, Russia, China, or some others. These other nations will provide international verification that the missions are peaceful. The missions can by financed by the USA, and any other interested nations, and verified by Russia, China, or other nuclear power. We might try something with Apophis when is comes by in the near future. Other than experimenting on a few nearby objects, most of the missions will be probably very far away, beyond the orbit of Mars. How far away is the nearest NEO of significant size?

Because we already have plenty of nukes, we should at least explore the possibility of using them for short-notice NEOs. Send robotic probes to several Earth-crossing NEOs. They should have the ability to test the object for how solid it is. They also have a nuke on board to test an explosion at a safe distance if the object is solid enough. Even if the NEO is a loose rubble pile, a series of nuclear explosions at an appropriate distance will only HEAT up one side of the NEO. Then outgassing will push it slightly. We should at least test the idea before embarking on far more expensive and time-consuming projects like gravity tractors. But why not test both? The money is there for robotic missions, since cutting manned missions from the NASA budget is a huge savings.

Asteroid pushing practice! We would look to the world like the good guys if we convinced the world nukes are an efficient means for saving the world from doomsday. We embark on robotic missions to NEOs and see what kind of effect nuclear explosions in close proximity will do to alter the path of asteroids and comets of various sizes and compositions.

Exactly correct, there must have been preconditions to initiate a Big Bang. Even though we cannot see, or detect, something does not mean there is nothing there. The "Nothing" before the Big Bang may be like dark matter, something very substantial, yet invisible, and not yet even detectible. For example, higher dimensions that collided to cause the BB, or something else. That something else is not nothing.

Space-time expanded with the Big Bang. "Space" was the pre-existing condition before the BB. Time depends upon matter to exist. Before time, before matter, there was only space, not space-time.

The center of a galaxy was an extremly dense place at a critical time during galactic formation, like our solar system forming, but on a much grander scale. The center became incredibly massive rapidly and like a cosmic vacuum cleaner sucked up all the gas in the immediate area. This rapidly formed a massive ball of hydrogen gas, over hundreds of thousands of solar masses. The SBH formed not over a period of millions of years, or even thousands or hundreds of years, but at some critical point in time it formed over a matter of minutes or a tiny fraction of a second. Even before nuclear fusion could start, it was already too massive to become a star and instantly crunched itself into a SBH. After the initial "Big Galactic Crunch" the remaining gas around the center had enough angular momentum to continue slowly feeding the new-born SBH with a steady stream of gas igniting a quasar. Over millions of years it eventually swept the center of all loose hydrogen and went dormant. Millions of years later the surrounding disk of gas gradually formed stars. So maybe the formation of the central SBH happened so quickly that it created the first light in the universe after the Big Bang in a huge instantaneous flash, greater than any supernova or quasar, and a quasar was born. The stars took much longer to begin nuclear fusion. From wikipedia: "...Another model of supermassive black hole formation involves a large gas cloud collapsing into a relativistic star of perhaps a hundred thousand solar masses or larger. The star would then become unstable to radial perturbations due to electron-positron pair production in its core, and may collapse directly into a black hole without a supernova explosion, which would eject most of its mass and prevent it from leaving a supermassive black hole as a remnant. Yet another model involves a dense stellar cluster undergoing core-collapse as the negative heat capacity of the system drives the velocity dispersion in the core to relativistic speeds. Finally, primordial black holes may have been produced directly from external pressure in the first instants after the Big Bang." http://en.wikipedia.org/wiki/Supermassive_black_hole Recent news about SBH: "On 4 January 2010, at the meeting of the American Astronomical Society, Julie Comerford of the University of California, Berkeley, presented evidence derived from the W.M. Keck Observatory in Hawaii and the Hubble Space Telescope of 33 merged galaxies with pairs of supermassive black holes orbiting around a common center at speeds exceeding 4,600,000 kilometres per hour (795 miles per second!)."

After the Big Bang cooled somewhat, and space became transparent, the expanding gas of hydrogen, helium, and only a few other light gases, there was a fairly uniform gas medium as explained by cosmic inflation. This gas clumped into regions that later became galaxies. As the gas attracted itself on massive scales, there grew huge proto-stars. Near the center of the galaxy there was much higher density of gas crashing into itself very violently, rapidly forming giant stars that immediately crashing into each other, quickly forming a great black hole before there could be any supernova. Then all hell broke loose, and the infant black hole started feeding on giant nearby stars in a frenzie, igniting the quasar.

"Space" is not what we are familiar with. We only know about space-time. Without the time dimension, there is only eternal space, far beyond the confines of a local Big Bang. Suppose Big Bangs are localized events separated by unfathomable distances, like a Googleplex light years between Big Bangs.

Yeah, what's the mystery? Anyhow anything that is Millions or Billions of solar masses that is nearly invisible, is inherently mysterious. I sure would like to see a real picture of a supermassive black hole (SBH), other than a tiny dot. So, if most galaxies are assumed to have a SBH at its' center, would that imply that most, if not all, galaxies start out as quasars, crushing dust and gas, and everything else, down to atom sized and blasting out incredible amounts of energy, continuously for millions of years, from its' poles? Can the age of quasars be determined? Would all quasars, and probably all SBHs, have formed before stars formed in their galaxies? That is with the exception of mergers of SBHs when galaxies collide. Could the first "light" in the universe, after the dark ages, have been quasars forming?

Thanks for the link VP. Interesting stuff, oceans on Venus long ago. Wow.

According to Wiki, the distinction between meteoroid and asteroid is SIZE. Meteoroids are small, from a grain of sand up to 10 meters in diameter. Asteroids are larger. "...The Royal Astronomical Society has proposed a new definition where a meteoroid is between 100 µm and 10 m across. The NEO definition includes larger objects, up to 50 m in diameter, in this category...." What I think is interesting about meteoroids is how fast they may be moving and at what speeds they can impact Earth, especially when going the wrong way: "Meteoroids travel around the sun in a variety of orbits and at various velocities. The fastest ones move at about 26 miles per second through space in the vicinity of Earth's orbit. The earth travels at about 18 miles per second. Thus, when meteoroids meet the Earth's atmosphere head-on (which would only occur if the meteor were in a retrograde orbit), the combined speed may reach about 44 miles per second." http://en.wikipedia.org/wiki/Meteor#Meteor WHEN IN DOUBT, WIKI IT OUT.

Easier is have a robot submarine do everything people can do. It won't be long before jet fighters, submarines, tanks, (as well as all ocean exploration) are robots controlled remotely. Like the robotic camera that went thru places on the Titannic that a human could not travel as gracefully.

That sounds good Mr. Alien. So that means over a year from now there may be something interesting to report, and a year after they crank it up full power several years from now, there might be a God particle, or something, after 4 years. What if they don't find anything new? This is like waiting for the Kepler mission to report on Earth-like planets.

Thanks for the link Arch. I must sound like a kid on his way to the amusement park, "Are we almost there yet, are we almost there?" Since they will not even turn up the LHC to full power for several years, we can expect to hear something interesting within the next what? Months or Years? What do they see already? Collisions began on March 29th. They've had a few days and there are "dozens" of technicians working on it. Are there 24 hour shifts?

The time lag between reactions will be an issue. The robot will need to be able to respond instantly to it's environment for survival. The controller may simply take a break for several minutes, hours, or days, between each change in commands, or for initiation of complex actions. But other than that inconvenience, the controllers may feel like they are really there. You can have many minds working on one experiment by this remote viewing. Merged post follows: Consecutive posts mergedThere is a way to have a sort of "virtual reality" control. First you map the area of exploration. If an asteroid you can image every square foot of it from an orbiting camera. Then that image of the object goes into the computer and recreates a CGI of the object, or area of exploration if on one of Jupiter's moons, Europa for example. The controller enters original location, along with the speed and direction the traveler is rolling over the alien landscape. And the computer can advance the perception of the controller on Earth's to match the virtual Europa. So his perspective would match in real time the location of the traveling robot. It is not the reality the robot is facing that very moment, there is a real time delay of only one hour, at the most for the Jupiter system, but it gives one additional perspective to use when following the mission. So the time delay for missions to Mars and the asteroids would be much less, only half an hour or less. Just explore slowly.

They just started up 3-30-10 to 3 times the previous power record. When will we hear some news? They keep repeating their mantras about finding the God Particle Higgs boson, a scientific revolution. And just what else is inside matter? Higher dimensions? It seems like it will take a long time before anything new is revealed. http://www.huffingtonpost.com/2010/0..._n_518196.html

The Large Hadron Collider (LHC) is dedicated to resolving the dark matter issue. They are just starting to work on this on the LHC. Just yesterday they turned up the power to 3 times greater than ever. It will be years before they even turn it up full power. How long will it take before they report real results and discoveries? Will they discover the "God particle" Higgs Boson? It seems like it will take a long time before anything new is revealed. http://www.huffingtonpost.com/2010/03/30/lhc-news-large-hadron-col_n_518196.html

Why the trouble of putting people into such harsh environments when a robotic probe can do almost everything people can do. Maybe not yet, but in the near future robots will be able to do a lot. Merged post follows: Consecutive posts mergedWhat would be easier? Have a team of controllers here on Earth, in a comfortable environment, watching 3-D video feeds, coming from every direction, from the Moon, Mars, or the asteroids (heck even Europa and Titan!). The controllers will feel like they are there in virtual reality. The robot can be MORE sensitive than a human. It can have "eyes" on the sides and back of his head, and detecting all sorts of other things we don't even know about yet.