PaulWDent

Lots of good questions about Black Holes to which I want to add these: I think I am right in saying that, the larger the Black Hole (i.e. the greater the radius of the event horizon), the smaller the gravity gradient at the event horizon. So matter falling in does not necessarily get torn apart while still outside. Especially if it falls in in a straight line plumb dead center. So imagine that situation. Now, just before the matter enters the Black Hole, it is not part of the Black Hole's mass, and the event Horizon radius is determined only by the mass inside. After it has fallen in, the Black Hole's mass and the radius of its event horizon must increase. So, the $64000 question is: At what point does the Black Hole's event horizon radius increase? Does it come out to meet the falling in mass like a big snake's mouth opening up? If so, does the Black hole get a bulge on one side? And does that bulge subside as the matter plummets towards the central singularity? I have a big problem with the latter, because that implies we are getting information on the outside about what is happening inside. I have other reasons to want to believe that mass can never be absorbed by a Black Hole except in a spherically symmetric manner. Or maybe in a cylindrically symmetric manner at least, if there is angular momentum involved, but I strongly prefer the spherically symmetric constraint, at least when there is no angular momentum involved. In the latter case, the matter thus covers the event horizon uniformly and continues its chute towards the central singularity as a sphere of collapsing radius. Does anybody have any opinions or math on this?

I vote for FORTRAN for modelling. I have used Compaq Visual Fortran many years. Intel took that over and it has become Intel Visual Fortran, which is excellent too. The reason I like Fortran is this: In order to read something, you have to be able to pronounce it in your head. You can't "pronounce" C, because of excessive use of punctuation marks and curly brackets and suchlike. FORTRAN is much more easily readable, and therefore you can pick up somebody else's code and figure out what is going on much easier. Another problem with C is that, to figure out whether a name is a integer, a floating point quantity, an array, a function or a procedure, you have to look at the declarations, which might be pages away. In FORTRAN, it's obvious. Visual Fortran even uses color to help with this. See attached picture of the code for a recursive FFT that I wrote.

A nice thing happens when the rekative velocity (due to expansion) between two galaxies is proportional to the distance between them. That is, you will observe exactly the same rate of expansion wherever you are, and every other galaxy appears to be moving away from you. Wherever you are seems to be the center! Reduce it to one dimension to make things easy: Consider a stream cars accelerating away from a stop light. The car 1000 meters ahead is already doing 100km/hr The car 800 meters ahead has only reached 80km/hr. The car 600 meters ahead is only doing 60km/hr, and on on. The car 800 meters ahead sees the car 1000 meters ahead, that is 200 meters ahead of him, doing 20km/hr faster than he is going. It's 200m away from him and receding from him at the rate of 20km/hr. That's the same relative-velocity-versus-distance law of 10km/hr per 100m of separation. He also sees the car 600 meters ahead of the stop light but 200 meters behind him, which is going 20km/hr slower than him, getting further behind him at the rate of 20km/hr. So cars both in front and behind seem to be receding from him at a rate of 10km/hr per 100m of distance away from him. He therefore thinks he is the center of expansion! (But every car sees the same thing)

What came "before" the Big Bang? "Before" is an adverb of time. Is that the right adverb to use for this question? I want to introduce a train of thought I have been developing for many years. 1) Current estimates of the size and mass of the universe place it entirely within its own Schwartzschild radius ro. We exist at r<r0. (Prove this for yourself then consider the implications!) 2) For r< r0, the sign of the time and radial terms in the metric are reversed compared with r>r0. Therefore a "time" question posed in our r<r0 universe should be mutated to a "where" question for r>r0 and vice versa. So my answer to "What came before the Big Bang?" is: "The Outside" (i.e. a place, r>r0) Likewise, the answer to "Where is the "place" r=r0 ?" is: 13.7 billion years ago. This has the potential to explain everything, without Cosmological constants, and without Dark Matter. This is what I work on in my spare time! That accords with my thinking. Coalescence of Black Holes, to form the Mother of All Black Holes: Our Universe! The total mass plummets towards the central singularity. 90% of it has already got there, or is ahead of us in time, at least. We are the remaining 10%. We have been plummeting for 13.7 billion years already, with perhaps another 10 billion to go. The metric where we are will be found to be that of a universe expanding at exactly the observed rate. Moreover, the closer we get to the central singularity, the faster the expansion becomes (It was also very much faster 13 billion years ago - and infinite at 13.7 billion years ago; it's a bathtub curve and will become infinite again at The Big Rip) The RW metric of an expanding universe suggests that there is a uniform density of matter causing it (the 90% of the mass that we can't see, for which the term Dark Matter has been coined). But the reason we can't see it is because it is ahead of us in time (nearer the central singularity) (Note: the radial dimension inside a Black Hole is the time dimension for physical phenomena. The Old time dimension (that which existed outside) becomes the spatial dimension inside) Furthermore: GR says planets orbit stars and stars orbit galaxies and light moves along geodesics. The geodesics are totally computable from the metric. So if you have a metric that looks like that of a matter-filled universe, the geodesics are going to be those of a matter-filled universe, whether there is actually matter (Dark or otherwise) there or not. So we just have to compute those geodesics to see if they explain the anomalous rotation of the galaxies. I have taken a first cut at this and am getting too big an effect so far, but there is a whole slew of conceptual problems dealing with orbits around a gravitating point particle within a semi-infinite uniform distribution of matter that I would like to understand how Newton would have dealt with first, before trying to translate the problem to GR. For example, Newton says all mass outside your orbital radius has no net gravitational effect. But orbital radius measured from where? Is one hydrogen atom enough to define a center?