Friday, December 21, 2012

Why I am sad it is not a re-collapsing universe

Why I am soooooo sorry that we are apparently (meaning according to the latest astronomical data and relativistic cosmologies) no longer in a closed (re-collapsing) universe. According to the latest, the expansion of the universe is decelerating, but at an ever lower deceleration which will cumulatively not be enough to turn the expansion around. 

How terribly sad! Suppose that there were to have been enough mass density in the universe to cause the universe to stop expanding and then to contract. Then there are theorems in GR which state that within a finite time everything will recollapse to a final singularity. 

Now, listen closely: We would then already be INSIDE the event horizon of the final singularity. Yes, you, me, the earth the sun the solar system the galaxy the local cluster the supercluster etc. You don't notice anything different do you? No "the earth shook" nor nothing, nada? 

Being inside the event horizon of a sufficiently large, isolated Black Hole would feel exactly the same.

"But if I was inside the event horizon of a Black Hole wouldn't I be able to see the Black Hole I was falling towards!?"

Nope! A Black Hole, like any final singularity, is like next Monday. You can't see "next Monday" can you?

End of the World

In case you missed it, the world did end, exactly according to prophecy. The end of the world started at the barycentre of the pyramid of the magician in the Yucatan and radiated out at the speed of light.

But the idiots who translated the prophecy forgot to translate the second page, which also prophesied that a new world would start with exactly the same initial data as was present on the outgoing lightcone of the end-of-the-world event. You didn't notice anything did you?

But what I really don't get is the self-hating "Westernized" Hindoos who fall all over each other to believe in the "new-age misinterpretation of Mayan calendar - the Maya Y2K" end of the world prophecy. Don't we have enough of our own revered and ancient crackpot astroboogers to believe in? Why do you have to outsource your insanity and take away domestic jobs from our own jyotishis and jadi-booti vendors?

Physics Phriday - It is a Time Machine

From Jack van Ryswyck:
You know it's funny you should mention that. The other day I suddenly saw Mike vanish before my very eyes, desk chair and all. Left in his place was a box shaped area of seemingly totally empty space, filled with absolutely nothing but some strange looking radiation.

Two seconds later Mike suddenly reappeared, looking very normal. In fact, looking rather exactly like he had at the moment he vanished. He then looked at me as if I had done something totally strange.

He told me that he had not seen anything vanish at all, but to him it looked like I instantaneously had shifted position and facial expression, as if I were an old time movie that had skipped a few frames. We then noticed that the atomic clocks that we had coincidentally been carrying were inexplicably off by 2 seconds. We had just synchronized them earlier that morning, but now his was 2 seconds behind mine.

Some time later a very similar thing happened, but this time a part of his desk chair stayed behind when Mike and the rest of his chair vanished. The remaining part of his chair just got cut clean off and fell to the floor. Mike and the rest of the chair reappeared two seconds later, though the chair did not reassemble. He said that he saw part of his chair suddenly teleported to the floor instantly.

Then the other day Josh and I were passing juggling balls when the same thing happened again. Suddenly everything in the box shaped area vanished, and many copies of a juggle ball appeared, all moving in a parallel direction. I then found myself tossing a juggle ball into the box. Oddly enough it happened to have the same colour as all the copies, and by some mysterious coincidence it was moving in just the same direction. Two seconds later all but one of the balls disappeared, and everything else reappeared. At the far side of the box, one juggle ball flew off. The net effect was just as if I had thrown the ball across the box incredibly fast. Impossibly fast really.

The next time it happened I saw the empty box appear filled with many copies of about one-third of a juggle ball. All but one of them were moving in a parallel direction away from me, but the nearest copy seemed to be moving towards me. In self defense I grabbed the juggle ball nearest to me, which happened to be the same colour, and as a makeshift missile defense system I threw it against the partial juggle ball that was moving menacingly towards me. They collided. The partial ball got knocked into a trajectory parallel to all the others. My defense missile ball got nudged back towards me. Then all the partial balls disappeared, except one that flew off at the far side. My defense missile ball was suddenly missing about a third of it. The remainder fell to the floor. The part that fell to the floor on the other side of the box seemed to fit it exactly.


Friday, December 14, 2012

Physics Phriday

Take your time on this one, as many times as you wish.

The first image is a model of a 1+1 dimensional spacetime, the time axis is vertical, the x axis is horizontal, the speed of light is 1, the orange cone is the light cone and the blue line is the world line of any physical object. At any point on it the world line is confined to the future (+) and past (-) of the light cone at that point, and the point always moves forward in time.

In the second image, I've done some "manifold surgery": I've made a cut each at t = -1 and t = +1 each of which extends from x=1 to x=3. Now I restitch them, but stitch the bottom edge of the lower cut to the top edge of the upper cut, and also the top edge of the lower cut is stitched to the bottom edge of the upper cut.

What have I built?

Friday, December 7, 2012

Mirror Mirror

Sex advice to the young (25 year-olds)

Not to the “young at heart”, just “young”.

If you expect to have a long and satisfying sex life, or just a long sex life, you should now start fucking a 30-year old, a 40-year old, a 50-year old, a 60-year old, a 70-year old … because if you expect to have a long sex life and hence a satisfying one, at some point you will be fucking a 30-year old, a 40-year old, a 50-year old, a 60-year old, a 70-year old …

… or you will be fucking somebody who is at that moment fucking a 30-year old, a 40-year old, a 50-year old, a 60-year old or a 70-year old …

… so you might as well start getting accustomed to it now.

Friday Night Epiphany

Most Private Thing I'm Willing to Admit Dept.

No matter how explosive the sex, no matter how available they were tonight and might be in the future, no matter how horny you were nor that you had just wanted to fuck and had imagined a long night of mutual pleasure, no matter that for a day or two it might help you avoid pining over someone or something unattainable - sex with someone who seems not to like you is just deeply unsatisfying.

Ask yourself, did you want to fuck them a second time?