Martin

Test test test evolution is just continuing, like at the waterline boundary (sea-land, water-air), or at the boundary between Siberia and Alaska. Now it's just a different boundary, but the evolutionary process is the same. Life forms spread if they have evolved the ability and inclination. If not, they don't. In some sense selection favors those able/inclined to spread because they come to occupy more of the environment.

I see no reason to agree totally with foodchain's line of argument (which strikes me as full of straw and not terribly coherent.) The Fermi question is still complicated and interesting, IMO. Nor do I see any reason to be sure, that the solution is along the lines suggested by foodchain. Maybe it is time to reopen discussion and hear what members think. EDIT: I just saw DH's post, which looks pretty good!

Quite true! Where do you get the "thus"? Of course one can define a preferred reference frame, simply by preferring it if there is some good some reason. Absolutely true! Mathematically speaking I would say in fact that GR validates SR, because it reveals why SR works so well. SR is the flat solution to the GR equation that you get when there is no matter in the universe to curve it, and no expansion. SR is one of the solutions of GR, one of the special cases. One can say that because GR is true therefore SR (the minkowski metric) must work as a good approximation in small enough neighborhoods where the matter density is low enough. Globally, the SR (or minkowski) metric describes a universe with no matter in it (no curvature, no gravity) but it works locally as an excellent approximation in low matter density, like where we are (for practical purposes even a solid brick is low density, you need something much denser to cause noticeable curvature at small scale. SR is fine and consistent with GR to a good approximation. GR is more basic, it underlies SR----provides a reason why geometry is the way it is. I think where you get into trouble is where you try to make SR say things it really doesn't say. GR deals with a more complicated world, with matter in it and in GR there can be reasons to prefer a coordinate system. And you can have other solutions to the GR equation which are not the particular SR solution called "minkowski space". One way to say it is that not all solutions to GR are "minkowski space"*. Not all metrics are the minkowski metric which is used in SR and which is basic to SR. *Globally I mean, all solutions look like minkowski space approximately in a small neighborhood---SR always applies locally. As far as I know GR does not undo anything that SR actually proved. SR is one possible solution of the GR equation, but it should always be thought of as a special case. There are other solutions, other metrics, other geometries, that solve the GR equation (like Friedman universe, de Sitter universe) which would contradict what people may mistakenly suppose that SR proved. Like this thing about not being able to have a preferred time coordinate or preferred spatial slices. SR never proved you couldnt prefer some particular frame if there was a good reason to prefer it. Of course people using the unpreferred frame see different simultaneity---they slice spacetime differently---that's their lookout. Does this make things any clearer for you?

I agree that it is impossible to set up a universal reference frame, in the sense of rectilinear coordinates, flat non-expanding space, and so forth. A reference frame in the stye of 1905 special relativity could hardly be global. I haven't studied what asprung is saying. For all I know he is wrong about some things. But is he really trying to set up a global reference frame? Maybe all he wants is a universal time coordinate, a natural slicing of spacetime into spatial slices, a natural notion of global simultaneity etc. Those things are routine in cosmology, so they are certainly not ruled out by the basic GR theory! Indeed they are built in to the standard Friedman model that everybody uses in cosmology. You are citing wikipedia on special relativity. This is the 1905 theory which has only limited applicability. It does not appy to the universe as a whole. Special Rel was superseded in 1915 by general relativity. In GR you can have solutions---like those used in cosmology---which have a global time coordinate. Relativity does not preclude a universal time coordinate, a natural slicing of the entire spacetime into spatial slices, a natural notion of global simultaneity etc. These things can be properties of particular solutions of the general theory. I'm talking not about a "frame" (not the appropriate term here) but about a foliation, or slicing. I think we should be careful about talking about a global reference "frame", because frame is basically a local concept. "Global frame" is somewhat of a contradiction in terms. Merged post follows: Consecutive posts merged Asprung, there are several ways that universal time can be measured, but they aren't very precise. They are based on the standard model of the universe used in cosmology (that is the context where expressions like "universe time" and "Friedman time" come up). I'm not sure I understand what you are driving at in your thread, it sounds kind of philosophical to me. If I understood I might or might not be sympathetic, might or might not be interested. Can't tell. But if we just want to look at the simple question of how do you measure Friedman time? That's easy. Anywhere in the universe, any observer as long as he is not too far down a gravity hole, and approx at rest relative to the Background, should measure the same age of the universe. That's all it is. Absolute time is time since the start of expansion. Or you can date things from the emission of the Background photons (which came some 380,000 years later.) You get it with these two equations (using a programmed calculator): http://en.wikipedia.org/wiki/Friedmann_equations These are built into various online calculators, like this: http://www.astro.ucla.edu/~wright/CosmoCalc.html So you don't have to work directly with the equations (i.e. with the equation form of the model.) All you need is to type two numbers (to wright's calculator for instance) and press "flat". It will tell you the age since start. That's your time teller, and anybody anywhere in the universe can do the same thing. We could make a much simpler online calculator that would do it. Wright's calculator is meant to serve a lot of different needs so it looks complicated. What we are using it for here is very elementary. Ignore all the other stuff on the calculator. The two numbers you put in are hubble parameter and matter density---in Wright's notation H0 and OmegaM. They are at the top left. They are the first two boxes where you could put in a number! Let's say it is a few billion years in the future and H has gone down to 65 and matter density is down to 0.13 put those into the calculator and press "flat" and what do you get? I get 18 billion years. Now, any alien anywhere in the universe can look at the sky and see that H0 is 71 and OmegaM is 0.27. If you make sure those two numbers are in, you press flat and you get 13.7 billion years. That is the time now. Any alien anywhere, who wants to know the time, can read it right now from the sky in exactly this way: 13.7 billion years. His calculator might work in different units, different years, but no essential difference. I'm being pretty loose numerically. Maybe I should make this more precise--but that could be in another thread. In the meantime, does that address your question? You said uyou would welcome description of how to measure universe time. Merged post follows: Consecutive posts mergedIt's actually even simpler. You only have to make one measurement, measure one thing, and the model tells you the time. I just posted how that works in the "CosmoBasics" thread.

As usual I can't say thanks with the button, because of the spread-around quota:D, but thanks anyway. I put a table here http://www.scienceforums.net/forum/showthread.php?p=489157#post489157 that makes it easier to tell time either just from measuring background temp or from measuring the Hubble rate. That simplifies everything. If you want to know the time you just have to measure one number. It might be the Background temperature or something else. You have a choice. Long range clock in the sky

Questions keep coming up about the usual global time in cosmology. For example someone asks how can someone anywhere in the universe tell this time? There are various ways, like measuring the temperature of the Background for instance. It declines as a predictable function of time, so you can tell time by it. Admittedly crude because temperature measurement is only so accurate, say to within one part per million. So your clock would only be accurate one part per million which is not very good. But its the concept. Another way to tell universe-time is to measure the Hubble rate. This also is crude. It is around 71 currently. (The units they measure it in are an historical accident, not especially convenient, but that's how it is.) I decided that I'd tabulate some expected future values of the Hubble rate. age scale estim. Hubble rate 13.7 1.00 71.0 14.1 1.04 69.0 14.6 1.08 68.2 15.1 1.11 67.5 15.6 1.15 66.9 16.1 1.20 66.2 16.7 1.24 65.6 17.3 1.29 65.1 17.9 1.35 64.6 18.5 1.40 64.1 19.2 1.47 63.7 19.9 1.54 63.3 20.6 1.615 62.9 21.5 1.70 62.55 22.3 1.79 62.25 23.2 1.90 62.0 24.2 2.02 61.7 25.2 2.15 61.5 The scale ratio is just how I'm keeping track of the expansion. The age is currently 13.7 (billion years) and by the time it is 24.2 longrange distances will have doubled, increased by a factor of about 2.02. That means the Background temperature will be half what it is now. 2.728 kelvin/2.02 = 1.35 kelvin. So if you should suddenly be transported to some other unknown location in the universe, and some other time in the future, and you want to know what time it is, then you can see all you need to do is measure the background temperature. If it is 1.35 kelvin then you know you have been transported to year 24.2 billion. It's obviously absolute and it is based on general relativity---the Friedman solution to the basic GR equation. Likewise if instead of measuring the temperature you look around and compare distances and redshifts and measure the Hubble rate (just like Hubble did) and if you find that it is 61.7 km/s per megaparsec (or whatever units the aliens on that distant future planet are using) then you can say immediately that you are in year 24.2 billion. It isn't especially accurate but you an tell the time by looking at the sky---whenever wherever in the universe.

Maybe some people will want to try this. It uses the cosmos calculator. Google "cosmos calculator". Let's say you are an alien somewhere in the universe, in the future, and you want to know what time it is (how old expansion is). You can measure the Hubble rate and you find it is 60.8, instead of the 71 we have today. From that you can determine the critical density for flatness, and you can see the universe is approx flat, and you can measure the average density of matter and find it is 0.01 of critical (instead of the 27 percent it is today it is only 1 percent because this is far in the future.) So you do something very simple: go to cosmos calculator and put in 0.01 for omega and 0.99 for lambda and 60.8 for the hubble rate and press calculate. This will tell you the age of the universe (current expansion phase) for that alien. ======================== Keep in mind cosmos calculator is not quite as precise as Wright's so it gives answers that are more ballpark in some cases, but we can still do something interesting. Pretend that alien in the future points his telescope at the Milky Way and finds that it has redshift z = 2.23. So you already put in Omega = .01 Lambda = .99 H = 60.8 So now put in z = 2.23 and press "calculate" and see what you get. What you get is us! The alien sees us. And for us the age of the universe is approx 13.7 billion (it will get it nearly right) and for us the hubble rate is approx 71 (it will say around 70 which is close enough.) http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html It gives a nice change of perspective because with that calculator we are used to reading "age now" as the present age for us 13.7 and we think of "age then" as the age when some ancient galaxy emitted the light we are seeing now----then is some time in our past. But the calculator lets us look at things from the perspective of someone far in the future, and it says that HIS "age now" is, say, 31.7 billion. And for him "age then" is close to 13.7 billion because he is looking at us, and that is the age of our now.

You are suggesting people engage in a line of pure speculation. To help them engage in that, could you provide some links? Right now there's not much definite to go on. What theory are you talking about? To be a scientific theory it has to at least in principle be testable. If you can't describe tests, then maybe you are talking about a non-scientific theory? Or could it be a vague impression based on somebody's verbal description? Philosophical theory? I can't tell from your post. My point is you need to be more specific about what the speculation is about, even if it is just pseudoscience or philosophy. Maybe a few of our members can help you get this solidified into somethng more concrete. ================== Oh, you mentioned string. There are a lot of different versions none of which quite work. M-theory does not exist as yet---it is conjectured to exist but there is no exact formulation in terms of equations, physical principles etc. Different versions of non-M [perturbative] string say different things, operate on spaces of different dimensionalities and compactifications. No one entirely satisfactory. Which versions of string do you mean? Maybe you could give a link to some research paper that would make it more definite for us.

http://www.livescience.com/animals/090430-birds-dance.html Some cockatoo research being carried out at Harvard.

There's been some quibbling about semantics of Arch's sentence. I take it to mean Swift satellite has imaged the oldest object in the universe that has been imaged so far. That seems true enough. If the object is still intact today---presumably it became a black hole after the explosion---it must now be some 13 billion years old. Clearly extremely old. Naturally our image of it is as it was when it was young. (The quibble that I think Meg was making.) But so what? Young when it emitted the light we are now receiving. But the object itself is old---the oldest macroscopic object we have direct specific information about. In astronomy one can never image material objects as they are today, one only sees them as they were in the past.

Nowadays there are stars whose lifetimes are that short. Check out http://nrumiano.free.fr/Estars/sequence.html If a star is very massive, it lives its life fast. The lifetime can be on the order of 1-10 million years. So to have a star which exploded when the expansion age was 600 million years is not contradictory or surprising. It does not in any way suggest that the expansion "is older than what we thought". 600 million years is plenty of time for a massive star to condense and form and live its life to the end.

You could try explaining how one would see a lightwave. A water wave can be seen because light is reflected off the wavy surface of the medium but how do you see the peaks and troughs of a light wave? A ring of detectors? Better specify. Setting that aside for the moment, I want to comment on "longer in the direction of the speed". If a circular hoop whizzes past me, I believe it's shape, for me, is oval but shorter in the direction of motion. Squashed in the direction of motion. Am I wrong? It seems inconsistent with what you said about the wave. Hopefully others will respond and help clear this up.

We have to distinguish between rotation-axis north, and magnetic north. I think the sun has a fairly well defined rotation axis, so when you said you were sitting in center of sun in normal position, head pointing north, I thought you meant head along the rotation axis north. but then you said you get flipped periodically! Then I was confused about what you meant. You must mean magnetic field north. If you want, explain some more (this will help me and perhaps others get what you are talking about)

Great find! Thanks. Estimated redshift z = 8.2

Universe time (or Friedman time, I've also seen it called)....I've never seen anyone spell out in detail how one would go about setting up a network of observers running that time in the real world. One would have to use powerful radios to communicate between galaxies and wait for 100s of million of years to get a reply, and so on. What you are imagining and what we are discussing is, I think, a useful thought experiment. I mean, universal time is obvious to define in a dust universe where the matter really is perfectly uniformly distributed, and that simplified model is pretty close to what we have, so one gets used to thinking in terms of that time---and it is approximately right for a lot of things. But then as a thought experiment we push the envelope and ask how would you establish that as a practical time standard in the real world? What concrete measures to take. Then problems obviously come up like, suppose galaxies are constantly colliding and merging so that over the years they change mass? If an observer lives in some galaxy at some distance from the center, you can't calculate a correction for his gravitational depth that will be constant always correct. Because circumstances change. These slight gravitational corrections are a great nuisance. It seems that one has to constantly re-calculate them. Maybe in the end one has to simply exclude all the observers who live in galaxies because it is too much bother to include them in the network....you see the difficulties of trying to do this rigorously. Also the criterion for being at rest. The CMB is not perfectly uniform, there are temperature fluctuations on the order of 1/1000 of a percent. That means you can't determine your speed relative to it better than 1/1000 of a percent. That is OK if you are nearly at rest because the speed doesn't affect time passage to any substantial degree. But maybe we should exclude observers who are moving at relativistic speeds. It becomes a kind of ad hoc, provisional make-shift affair, this setting up of a practical realworld standard time. Maybe someone smarter and more motivated than I could see how to do it in a way that would include everybody (even those, as you say, close to black holes). Yes! That's the idea. It is simpler to consider just two observers. And I'd go further, I would like them both to be at rest with respect to CMB, so there is no local speed to worry about and adjust for. Also let's take them both to be far away from concentrations of mass, so there is little or no gravitational effect. (I'm prejudiced in favor of simplicity and constantly slip into this mode.) Now, even tho they are widely separated and even tho the distance between them may be increasing at a rate which is several times c, they can both measure the expansion age of the universe and find that it is exactly 13.77 billion years and three hours! But if I had to deal with generic observers, who had been moving around in galaxies, then I would have to imagine the entire world line of a given observer. His whole history, say since the time of last scattering ("recombination", the CMB release date). At every epoch I would need to consider his gravitational depth and his motion relative to background. I'd have to integrate all those corrections. Or he would. Sometimes he would be falling towards a coagulating center of mass, a galaxy in formation. He would have to measure his speed relative to background. Sometimes he would be orbiting the center of the galaxy--he would have to measure his speed and his depth and adjust the readings of his personal clock (his "proper time"). He'd be keeping a log, with two time columns, his own personal atomic clock time ("proper") and the adjusted time ("universal"). At times another galaxy would collide with his, and tear his stellar neighborhood, with his planetary system in it, loose and fling it out into intergalactic space. You see computer simulations of galaxies colliding and this happens to parts of them---parts of them splash very slowly. The collisions are sloppy. So lots of things happen that affect his proper time (relative to universal) and they all get entered in his log. But finally when it was all accounted for he also would say that the universe expansion age was 13.77 billion years and 3 hours . Hopefully. I was thinking in terms of observers all of whose history is out in intergalactic space because it is so much easier to imagine adjusting their timekeeping to accord with universal. You are right to notice this habitual tendency, a kind of bias. If you were a Time Commissioner you could make an arbitrary choice of how to define the standard. Do you use zero gravity (gravity at infinity, so to speak) or average over your network of observers? I would prefer using zero gravity. Perhaps philosophical questions about that, but in practice it seems clear: get way out in space. Certain elements of comedy here. Timekeepers are a special breed. Finicky. A bit obsessive. I understand that nowadays standard earth time is a mathematical construct related to a putative clock at the center of the earth because they wanted to exclude the effects of rotation. Please don't ask why. Arbitrary choices are always involved. In fact universe time is a good idea, and used in mathematical models, but you would have a very hard time establishing a standard version of it. Maybe a practical impossibility. Good questions. Made me cogitate some.

some tangential reading: http://www.technologyreview.com/blog/arxiv/23292/ MIT Technology Review: "FTL travel not possible after all" http://www.centauri-dreams.org/?p=7101 arcane professional research paper: http://arxiv.org/abs/0904.0141 The research paper is co-authored by Stefano Liberati (world class guy). the FTL issue depends somewhat on whether your model is special relativity (vintage 1905 SR) or general relativity (vintage 1915 GR). Both are called "relativity" and both are courtesy Albert Einstein. Both indicate that you can't approach a given destination at a rate that is FTL (greater than or equal to c) but for somewhat different reasons. SR says that FTL without warp drive doesn't work because vehicle inertia grows without limit as it approaches c. GR says that FTW with warp drive doesn't work because you would have to deform the geometry of space in a way that would kill anything inside the deformed "bubble" region. Moreover, producing a "bubble" of exotic geometry would require a form of energy so far unknown to physics. And moreover if ever produced, the bubble would self-destruct---it would not be stable. (The discovered instability is what Liberati's paper is about.) This is all very interesting. But scientific theories are not meant to be believed, rather they are meant to be tested and re-tested and if necessary revised. It is risky to predict the future of research and human knowledge.

At the risk of adding confusion, I just want to contribute some links about one kind of high speed post-supernova remnant http://www.astronomy.com/asy/default.aspx?c=a&id=3471 (a neutron star leaving our galaxy at 1100 kilometers a second.) http://arxiv.org/abs/astro-ph/0608205 (neutron star going 1600 km/s) http://www.space.com/scienceastronomy/050906_fast_star.html (more about B1508) ====================== I don't remember how the earlier discussion went but I agree that the diffuse blow-off from a supernova would typically be slowed down by gravity and the surrounding interstellar medium. Gas, dust, lightweight stuff like that. I guess it would form an expanding sphere. That would interact with the surrounding stuff, and glow hot. I've seen pictures of that---looking like hot rings of glowing gas. You only see a circular section of the expanding sphere. I don't know about anything planet-size. Except for the neutron star core remnant. Compact debris wouldn't be slowed down in the same way as gas etc. A single massive star can collapse in a lopsided asymmetric way that gives the core remnant a kick. Also some supernovas involve a binary system, and one partner might be a neutron star and it might get slung out when the star it was orbiting blows up. There should be some discussion of at least the first case, in these links. ===================== 1000 km/s is pretty fast. The earth in its orbit around the sun only goes 30 km/s and the solar system in its orbit around the center of our galaxy only goes about 250 km/s as I recall. And we don't notice that because all the stars in our immediate neighborhood are like a flock of birds all flying in much the same direction, all orbiting the center of the galaxy in about the same direction. So we typically dont see relative motion of compact objects that is as fast as 1000 clicks. ====================== It should however be mentioned that space is fantastically big, so the liklihood of any compact object buzzing the solar system, or bashing one of our planets, is ridiculously small. It is only a theoretical possibility that one day a neutron star (of approximately the same mass as the sun) crashes into the sun at 1000 km/s and good-bye sun. It just isn't realistic to contemplate such things. :(

I believe the full moon is about half a degree wide.

did they specifically say a light bulb? what about a flashlight lightbulb? a couple of watts is easier to generate than 30 watts or 60 watts for that matter what about an LED? You used to be able to buy LEDs at Radioshack. And also they sold small DC electric motors for a dollar apiece. These were simple (permanent magnet) electric motors not much bigger than your thumb. They would generate a small DC electric current if you turned them. Or they would run toys if you hooked the motor to a couple of 1.5 volt drycells. DC low voltage components are probably simpler, safer, more forgiving than AC high voltage. If you want to start cheap you might be able to get some mileage out of Radioshack. My suggestions are off-the-cuff and may not be the best. Hopefully others will responds. I don't know if this is an appropriate solution for the SCHOOL project but if it were me and my 11 year old son (back then) I might break the project into two parts. 1. Have a weight on a string and have the hydroturbine wind up the string and raise the weight (visibly storing foot-pounds, or newton-meters, of energy) 2. then disconnect the turbine from the string-winding spindle and connect it to the electric generator and let the weight fall down, spinning the shaft and lighting the flashlight bulb.

You had better read two recent prize-winning essays on time (by two top experts). Both of them develop further ideas akin to what you have expressed. Click on PDF to get the full text. Rovelli "Forget Time" http://arxiv.org/abs/0903.3832 Barbour "The Nature of Time" http://arxiv.org/abs/0903.3489

Any intelligent woman would surely have been thrilled to have him! Unfortunately he caught typhoid fever and died young. http://www-history.mcs.st-andrews.ac.uk/Biographies/Friedmann.html What they do is correct the data so that it is as if it were measured by an observer at rest. This is not hard to do because the solarsystem speed is small---only 370 km/s (which includes both the galaxy motion and the motion of the solarsystem within the galaxy, combined) I think you can calculate the time dilation effect on the length of one second that results from moving at a speed of 370 km/s. Essentially the speed is 1/1000 of c. And then you square that. So what are we talking about? 0.999999? I think the way you put it, "close enough", describes the situation adequately. Yes! Cosmologists are always talking about the "dust universe". It is an idealization that you can compute with. Imagine matter all spread out uniformly as dust. For a lot of things that's a useful approximation to reality. Seems like you are on the ball and are asking very reasonable questions! Yes again! A rough formula for the grav. redshift is z = GM/c2r. Some numerator GM/c2 divided by r, the distance from the center of mass. And we don't differ if we are at the same depth within our respective galaxies. If I climb out of my gravity valley and walk over and descend down into yours then if it's at the same level then the clocks at each of our houses are the same. Since the effect is small it's no big deal in any case. You can estimate it. GM/c2 is half the Schwarzschild radius. For solar mass it equals about one mile. Say the mass of our galaxy, inwards from us, is 100 billion solar so the numerator is 100 billion miles. Our distance from galactic center is what? r = 30,000 lightyears? Our grav. redshift, relative to intergalactic space (far far from Milky) is z = 1011 miles/ 30,000 lightyears. It will be some extremely small number signifying that the grav. redshift effect of our being where we are in the galaxy (compared with out in intergalactic space) is negligible. I'll bet google will compute this "10^11 miles/30000 lightyears" Yes! Google computes it and says that it is about six tenths of one millionth. So a gravitational effect on time of the order of one millionth.

AFAICS no reason not to lock thread. In any case, it no longer has any connection with astronomy (if it ever did), and does not belong in Astro/Cosmo forum The thread was reactivated by posts of a poetical/philosophical or speculative nature by Thief. Thief, I'm personally open to the point of view that speculative philosophy can be helpful to physics and assist scientific progress. I think it has in the past. (Einstein and Bohr's contemporaries and the next generation after them were educated in the philosophy of science and it probably helped them ask the right questions.) But it does't always help. Philosophy is not always relevant. Only at certain junctions in the history of physics has it played a key role, I think. You are venturing into philosophical speculations about time (and related things, like movement, and cognition). Do you think of this as relevant to science? I'm curious. For example, how would your thoughts about time help a physicist solve some theoretical problem?

I agree with MacSwell on the general issue, but probably not at the level of detail. The simplest situation would be a small (solar mass) BH which falls in thru the event horizon of a supermassive (million solar mass) BH. The diameter of the big hole is say 6 million km. The diameter of the solarmass hole is only say 6 kilometers. At first the small BH doesn't even know it has passed in thru the horizon. Eventually its pit will coalesce with that of the more massive. But temporarily there would be a nesting of event horizons. I could be wrong. There have been some computer simulation studies of BH coalescing. We should check the literature. MacSwell would you be willing to do the search? Here is a place to start: http://arxiv.org/abs/0902.0136 An improved analytical description of inspiralling and coalescing black-hole binaries Thibault Damour, Alessandro Nagar (Submitted on 2 Feb 2009 (v1), last revised 19 Mar 2009 (this version, v2)) "We present an analytical formalism, within the Effective-One-Body framework, which predicts gravitational-wave signals from inspiralling and coalescing black-hole binaries that agree, within numerical errors, with the results of the currently most accurate numerical relativity simulations for several different mass ratios. In the equal-mass case, the gravitational wave energy flux predicted by our formalism agrees, within numerical errors, with the most accurate numerical-relativity energy flux. We think that our formalism opens a realistic possibility of constructing a sufficiently accurate, large bank of gravitational wave templates, as needed both for detection and data analysis of (non spinning) coalescing binary black holes." Comments: 5 pages, 5 figures, to apper as a Phys. Rev. D Rapid ============== I haven't looked at this, but I can attest that Thib Damour is top notch. And the thing is already accepted for peerreview publication. So the quality must be OK. Now this might not be the ideal paper on the subject, but it is recent and it will have footnotes and references to earlier papers. If you check out some references you may find a review paper that gives some pictures of the computer simulation output of merging black holes. Or maybe somebody else has a better idea of how to check this out. The ideal would be a computer animation movie of a BH merger. I seem to recall seeing one, but I've forgotten where, lost track of the link.

Kepler is now on station and is taking pictures. http://www.nasa.gov/centers/ames/news/releases/2009/09-43AR.html It will constantly watch a patch of sky about 10 degrees by 10 degrees wide-----100 square degrees. In this patch there are about 100,000 stars which have been identified as good candidates for finding "habitable zone" planets. The occasion on which a new telescope takes its first pictures of the stars is called "first light". Here are the "first light" pictures by Kepler: http://www.nasa.gov/mission_pages/kepler/multimedia/20090416.html