Airbrush

In our experience anything like the big bang would have a center. The big bang is supposedly not like an ordinary explosion which results in a shell of fragments flying outward in all directions leaving a central void. We do not see this anywhere in the universe. It has been suggested that the big bang could be explained by the balloon analogy. However that would make one visualize the universe like an expanding balloon which would have a definite center. Then one might guess that if our region of the universe is homogenious and isotropic, that could be explained as a "balloon" with a very, VERY, thick skin, in fact so thick that it would be at least as thick as the observable universe. Our observable universe would be very tiny compared to the entire universe. What we see in our region makes us suppose that there is nothing beyond the CMBR. This "thick-skinned balloon" idea fails, I believe, because for a unverse to be THAT large, the central void would be over millions of times the "thickness of the balloon's skin". A universe THAT large could not have originated only 13.7 Billion years ago. It would be at least millions of times older. But with things like cosmic inflation going on, maybe there are other kinds of cosmic inflation, which occurred at different intervals?

That's what I had been thinking. Why do the experts suppose the universe originated from a tiny point smaller than a proton? I think it would make more sense to say the universe originated from a region of indeterminable size and kept expanding. Also, how can they be so sure that inflation happened only once for only a tiny fraction of a second, before the universe was larger than a grapefruit?

How could Mars migrate from the vicinity of Jupiter, through the asteroid belt, to where it is today?

Before someone with more expertise replies, here are my best guesses to these good questions; Dark flow is what they call an anomaly to big bang expansion. Instead of expanding exactly the same everywhere, there is a region of unexplained directional expansion. Other than that, what you propose is beyond what can be observed. The simplest explanation is big bang. Also, some experts will say there is no "outside" the universe, since the universe is everything and everywhere. What can pull from the outside? Dark flow may indicate something outside. What you propose is the universe expanding at a constant rate, and then change rate. What can change the rate of expansion? What outside forces? According to string theory, the big bang was the result of a collision of higher dimensions, like two great sheets that came into contact and at the regions of contact big bangs started. The uniformity of the cosmic background radiation is evidence for the big bang and cosmic inflation as we know it.

An object 16 to 32 feet in diameter, as you note, will create an explosion of the Hiroshima A-bomb, but in the upper atmosphere. It might go unnoticed, or thought to be lightning and thunder. If it was solid iron it might not explode in the upper atmosphere, but it might survive to make an impact on land or sea. My question is how large of an iron, or other solid metal meteor, will it take to cause Hiroshima-like damage to a city? My guess is look up "Meteor Crator Arizona" and find out how large it was, then calculate based on that how large an iron meteor it would cause Hiroshima damage to a city. Here's what I found on wikipedia. Meteor Crator Arizona was nickel-iron 50 meters in diameter, 162 feet across, creating an explosion of 10 megatons of TNT. One half of its' 300,000 ton mass was vaporized on the way down, so 150,000 tons impacted. If Hiroshima was 0.15 megatons, then the metal meteor needs to be how many meters across? I calculated 0.75 meters, using directly proportional which cannot be true. Something is squared or cubed. Anyone know how to calculate this? If Meteor Crator AZ was 50 meters diameter and 10 megatons, then how large a metal meteor will cause a 0.15 megaton blast? Remember that half its' mass will burn up in the atmosphere.

So what you are saying is that even if matter decays into other particles and releases some energy, the energy released retains a gravitational effect? Suppose a galaxy could be converted 100% into energy. The energy will continue to pull on neighboring galaxies?

If or when protons decay there would be a flash of energy released. So matter is not destroyed only converted into energy and maybe some other lighter particles. But protons are supposed to have a very long life, so maybe the universe is not old enough yet for any protons to decay. "The spontaneous decay of free protons has never been observed, and the proton is therefore considered a stable particle. However, some grand unified theories of particle physics predict that proton decay should take place with lifetimes of the order of 10 to the 36th power years, and experimental searches have established lower bounds on the mean lifetime of the proton for various assumed decay products. "Experiments at the Super-Kamiokande detector in Japan gave lower limits for proton mean lifetime of 6.6 x 10^33 yr for decay to an antimuon and a neutral pion, and 8.2 x 10^33 yr for decay to a positron and a neutral pion." http://en.wikipedia.org/wiki/Proton#Stability

How about a skin of solar cells all over the blimp that heats the air inside instead of a gas burner? Or the solar cells heat up helium so it is more boyant, but not hot enough to ignite the helium?

You are correct. Probably water and food shortages will become an issue long before energy shortage. Sorry if I got too far off topic. It just seemed logical to me when discussing "the end of nuclear energy" and what remaining alternatives we have, that the QUANTITY of energy needed for a given world population could become an issue. But now I realize rising sea levels and resulting loss of coastal land, disrupted weather patterns which result in famine and severe storms, from global warming, along with wars fought over a shortage of fresh water, will become issues before energy shortage. Hopefully economic pressures will limit world population to reasonable limits, without the need for Big Brother to decide who gets to have children, and how many they can have. Have you ever heard of an energy shortage? Except for occasional power outages, and in places like Iraq, where people have power for a few hours each day, or no power at all. But that is not an issue, only an inconvenience.

Is the headline misleading? It makes it sound like they figured out dark matter. It says nothing about "non-baryonic" matter. They only explained missing regular (not dark) matter. This is a comment below the story by Steve Nerlich. "I think the deal is that this study confirms Bregman's prediction outlined here: http://arxiv.org/PS_cache/arxi... The universe recipe of 74% dark energy, 22% dark matter and 4% baryonic is unchanged. It's just that Bregman predicted that a lot of the baryonic matter would be in the form of Warm-Hot Intergalactic Medium (WHIM) - or filaments. This appears to be confirmed now, so good science all round. I'm not sure what the link with Zwicky is - who is not obviously cited in either the Fraser-McKelvie or Bregman papers, but might have missed something."

Maybe the "stealth" chopper needs to fly under the radar?

You are correct Lemur. However, soon it will become a very practical issue. We cannot discuss energy alternatives without considering population. Then, as you suggest, let's say NO limit to the populations of underdeveloped nations, since they use very little energy per capita, and excess people will simply starve to death. DO limit populations of energy hogs, like USA and other developed nations. The developing nations, especially China and India, will also need to limit their growing populations, because they will soon surpass the US as energy hogs. No energy sources can provide an unlimited amount of energy to unlimited world population. War is the quickest way to deal with overpopulation, especially nuclear war, but what a waste and what a mess. The Earth has a carrying capacity, but we don't know exactly how many people that is. Let's call it quits before there are really too many people.

I think it would be much greater leap into fusion energy than the leap into Apollo technology. Remember the computers used for the Apollo missions were less powerful than the average PC. Here's how to solve the energy crisis: (1) Limit population, (2) improve efficiency, exploit (4) wind, (5) solar, (6) wave/tide, and (7) other green energy sources. Fusion power will happen someday, but that would be LAST on the list.

Gravity did it all by itself. The universe has always been homogeneous. The puzzling fact is how homogenious the unverse is. The explanation is inflation. "Inflation is a concrete mechanism for realizing the cosmological principle which is the basis of the standard model of physical cosmology: it accounts for the homogeneity and isotropy of the observable universe. In addition, it accounts for the observed flatness and absence of magnetic monopoles. Since Guth's early work, each of these observations has received further confirmation, most impressively by the detailed observations of the cosmic microwave background made by the Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft.[48] This analysis shows that the universe is flat to an accuracy of at least a few percent, and that it is homogeneous and isotropic to a part in 10,000. In addition, inflation predicts that the structures visible in the universe today formed through the gravitational collapse of perturbations which were formed as quantum mechanical fluctuations in the inflationary epoch." http://en.wikipedia.org/wiki/Inflation_(cosmology)

Thanks for the info BJC. "Within hours of being installed, the machine had already detected at least two high-energy particles that have never been observed in nature before...." Wow, that was fast. If 500 scientists can agree on something and work together for 2 years on the same project, there must be something interesting in the works. "AMS's potential to analyze cosmic rays and particles is unparalleled and its findings likely will be invaluable...." I'm still waiting for the breakthroughs by the LHC, maybe someone heard something? And Kepler should start giving some definitive results soon, since its' last revelations. "With Obama administration plans to extend International Space Station operations beyond 2015, the decision has been made by AMS management to exchange the original AMS-02 superconducting magnet for the non-superconducting magnet previously flown on AMS-01. Although the non-superconducting magnet has a weaker field strength, its on-orbit operational time at ISS is expected to be 10 to 18 years versus only 3 years for the superconducting version. This additional data gathering time has been deemed more important than higher experiment sensitivity, despite the fact that the abandoned cryogenic system was originally described as critical technology to mission success. Whether the ISS will operate long enough for AMS to take full advantage of its extended lifetime is also unclear." "Six types of quarks (up, down, strange, charm, bottom and top) have been found experimentally; however, the majority of matter on Earth is made up of only up and down quarks. It is a fundamental question whether there exists stable matter made up of strange quarks in combination with up and down quarks. Particles of such matter are known as strangelets. Strangelets might have extremely large mass and very small charge-to-mass ratios. It would be a totally new form of matter. AMS-02 may determine whether this extraordinary matter exists in our local environment." http://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer

I believe I read the average density of the universe is about one atom per cubic meter. I also believe I read the average density of the middle of the great voids is also about one atom per cubic meter. My guess is that the average density of the universe is only a tiny bit more dense than the center of the great voids.

"The device will sit outside the space station, seeking to collect high-energy cosmic rays and space particles that have may have originated with the "big bang," which astrophysicists theorize created the universe. If so, the findings could help them understand the makeup and origins of the universe. Some scientists have expressed strong skepticism that the AMS will work, but others think it might become the greatest astrophysics tool since the shuttle took the Hubble Space Telescope into space. Even if it does not detect its primary goals -- big-bang antimatter and so-called "dark" matter -- the AMS's potential to analyze cosmic rays and particles is unparalleled and its findings likely will be invaluable, said its principal investigator, Nobel Prize laureate Samuel Ting. More than 600 scientists from 16 countries are involved with it. "We want to put a powerful physics detector, a state-of-the-art physics detector, into space," Ting said recently." 2 Billion dollars seem like a lot for a device to look for strange matter. Anyone who knows more about this please share. http://www.orlandosentinel.com/news/space/os-space-shuttle-launch-20110516,0,7742586.story

This is a great article I saw posted by RealityCheck in the "Iron Remnants..." discussion. How do we get to the nearest stars within 100 years? We could send probes to the nearest stars traveling at 12% light speed and they could beam their discoveries back to Earth within 60 years if the probe can reach its' destination in 50 years, give it a few years to explore the star system, then 4 or more years to transmit the results of its' exploration. "Project Icarus is an ambitious five-year study into launching an unmanned spacecraft to an interstellar destination. Headed by the Tau Zero Foundation and British Interplanetary Society, a non-profit group of scientists dedicated to interstellar spaceflight, Icarus is working to develop a spacecraft that can travel to a nearby star. Richard Obousy, project leader and co-founder of Project Icarus, and primary propulsion lead designer, discusses the propulsion options for an interstellar probe. What makes fusion particularly appealing for propulsion is the amount of energy that it releases when compared to chemical rocket fuel. A good rule of thumb is that, pound for pound, fusion releases about a million times more energy. Because of this, it is ideally suited for interstellar propulsion. In the 1970's, Project Daedalus demonstrated that with a spacecraft about the size of the Nimitz aircraft carrier, filled mostly with fusion fuel, a top speed of 12 percent the speed of light could be realized. This is truly an incredible speed, and travel to the closest star at this speed would take only 50 years. One of the many challenges in actually building this technological marvel would be the creation of energies high enough to ignite the fusion reactions which could then be used to propel the spacecraft. Daedalus used a process known as "pulsed inertial confinement fusion." In this scheme, small pellets of fusion fuel would be injected at a high velocity into a reaction chamber and ignited by high energy electron beams. Conceptually, this is not vastly different from a conventional internal combustion engine, where small droplets of gasoline are injected into a combustion chamber and ignited. The ignited fusion fuel would reduce the pellet to an expanding plasma radiating from the ignition point. The basic concept of the reaction chamber was to enclose the electromagnetic field of the plasma in a conducting shell. The shell would perform as a shock absorber, which would absorb the momentum of the plasma and transmit it to the vehicle. The process would occur rapidly, over a few microseconds, and the rise and fall in magnetic pressure would be received by the shell as an impulse which set it in motion. The resulting fusion reaction products in the Daedalus reaction chamber would be channeled axially rearward from the main vehicle by a number of field coils acting as a magnetic nozzle. These ejecta would be responsible for an overall momentum transfer mediated by magnetic fields interacting with the reaction chamber. The Project Icarus team is currently examining this and several other fusion propulsion schemes, and a decision regarding the main propulsion technology for Project Icarus will be made late in 2012." http://news.discovery.com/space/project-icarus-fusion-propulsion-starship-110405.html

Thanks for the good links DrRocket. It is astonishing to learn that they would sling shot probes around inner planets to throw they towards outer planets, and I suppose around outer planets to get shot towards the inner solar system, or around the sun in a polar orbit. My question for anyone is how much increase in speed can a probe get when getting whipped around Jupiter on the way towards the outer solar system? Like from about 15 miles per second to 20 miles per second? Or double?

Then explain how gravity could somehow bring everything back together in a big crunch when we see the universe is accelerating its' expansion. The universe has gone beyond its' own escape velocity. As space between superclusters increases the expansion accelerates even more. What can bring that back together? Correct that the picture isnt full yet. They are giving us their best guess. Do you think they suffer massive collective delusion? They admit they don't know yet and are simply trying to increase their understanding, just like you.

Nice explanation Spyman. Does this mean that when a probe uses Jupiter to gain speed, the probe is using Jupiter's speed in orbit to pull it faster and not Jupiter's gravity? Can you tell us how much percentage increase in speed, relative to the Sun, a probe can gain if using Jupiter to speed up? Would it be possible to use Jupiter, then Saturn, and maybe one or two of the outer giants, one after the other?

Not exactly. When Voyager missions were sling-shotted by Jupiter's gravity, the spacecraft took advantage of Jupiter's gravity to pull it faster, but timed it right so speed was not lost when departing Jupiter. Maybe a little velocity was lost when departing Jupiter, but there was a big net gain in speed and thus gain in energy. The trick is to approach from the proper angle and disengage at the right moment. All the outer planets may be used this way sending probes to the outer solar system.

The question is exactly when did the last reversal occur? Was it during the past million years? How did the reversal effect early humans? "A geomagnetic reversal is a change in the Earth's magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth's field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was in the opposite direction. These periods are called chrons. The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the BrunhesMatuyama reversal, occurred 780,000 years ago." http://en.wikipedia.org/wiki/Geomagnetic_reversal There were hominids at 780,000 years ago and they survived. Maybe our technology will suffer, but animals and plants seem to survive it.

You are denying what the experts in the field tell us? What do you know that they don't? Gravity will always exist, it will just be too weak to have any effect on the expansion of the universe. Dark energy is the "fuel" of empty space. So the more space there is between pockets of matter, the more fuel for accelerated expansion. Scientists believe what they do because they are on the front lines doing experiments and reading the data. I tend to trust them to know better than I do. What data have you been reading that they haven't? Sorry that they don't have the whole picture, they are just telling us the best they can with what limited information they have. And they tend to agree with each other on this issue.

Maybe a Big Bang can happen anywhere at any time. There hasn't been another since 13.7 Billion years ago, so as Captain said the chances are negligible during our lifetime. I'd instead worry about Yellowstone erupting.