The story of Joshua

I hardly started reading chapter 5 of Hawking and Mlodinow’s The Grand Design again this afternoon when I noticed something that I must have missed before. The authors talk of story in the Bible where Joshua prays for the sun and moon to stop in their trajectories so he would have extra daylight to finish fighting the Amorites in Canaan. According to the book of Joshua the sun stands still for about a day.

I must say, even if I take into account the couple of years I attended Sunday School as a boy my knowledge of the Bible is certainly not extensive. And, truth be told, it doesn’t much matter for the purpose of this. I’ve always assumed a vague connection between a creator and the planet we live on. It’s been more like “according to the bible God created everything.” Here, we a have Joshua, needing God’s help.

According to Genesis 1:1 in the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was on the face of the deep. And the Spirit of God moved on the face of the waters. And God said, let there be light: and there was light.

Clearly, God must have not only created the Earth and the heaven, God must have created everything else as well - a God creating every world. Here’s where I show my naivety. Why does Genesis limit God’s reach to earth and not to all earths – all worlds.

Before String Theory

I mentioned earlier that I’ve wanted to try and get some (basic) understanding of String Theory over the coming holiday period. I wondered if a survey of the topic might help me gain a better understanding of the underlying assumptions, tools, theories and techniques which forms a substrate on which String Theory is built upon. Like any highly specialized field, String Theory has been constructed on top of a vast array of mathematical concepts, mechanics, and physics.

Gerard 't Hooft Institute for Theoretical Physics Universiteit Utrecht) offers a menu of subjects (topics) which look to be a prerequisite in understanding and competence in order to make sense of this theory. Here is that list.

• Languages
• Primary Mathematics
• Classical Mechanics
• Optics
• Statistical Mechanics and Thermodynamics
• Electronics
• Electromagnetism
• Quantum Mechanics
• Atoms and Molecules
• Solid State Physics
• Nuclear Physics
• Plasma Physics
• Advanced Mathematics
• Special Relativity
• Advanced Quantum Mechanics
• Phenomenology
• General Relativity
• Quantum Field Theory
• Superstring Theory

An unimaginably massive object

I woke up today with the strange thought - tried to imagine what it would be like when a black hole is swallowed up by another larger monster.

Now I knew a few things about Quasars so looking for an orbiting black hole system would point me closer to black holes potentially coming into each other’s deadly embrace. And quasar OJ-287 doesn’t disappoint. This is a monster lurking some 3.5 Billion light years away.

In fact OJ-287 contains the largest black hole detected in the universe to date. OJ-287 has produced quasi-periodic optical outbursts going back approximately 120 years, as first apparent on photographic plates from 1891.

Its central supermassive black hole is among the largest known, with a mass of 18 billion solar masses. As this system tears each other apart the resultant black hole will be unimaginably massive not to mention its ability to bend space-time.

Object information

Speaking of space-time, this system provided further evidence for general relativity. 

The theory predicts that the smaller hole's orbit itself should rotate, or precess, over time, so that the point at which it comes nearest its neighbor moves around in space - an effect seen in Mercury's orbit around the Sun, albeit on a smaller scale.

Sequence information below.

Ghosts lurking around in advanced physics

Jack Dikian

February 2012

Lurking deep at the core of Gauge Quantum Field Theory are two Russian ghosts called Faddeev and Popov - somewhat reminiscent of the ghost monsters in the old video game; Munchkin. Luckily for us, these ghosts are also thought to be “good ghosts”. The bad ghosts, which apparently also exist in the strange and schizophrenic world of quantum mechanics are another thing altogether.

As the theory goes, these ghosts where send for so as to avoid the over-counting in the complex area of theoretical physics, to fix gauges and make path integrals right.

In high school, we were taught classical mechanics (remember fiction, momentum, force, gravitation, etc) and one of the things we learned was that the path of say a moving object (think of a ball thrown across the room) was that for which the action is a single unique trajectory, i.e., a stationary action [formulation].

In the world of the quantum mechanics, however, the stationary action formulation of classical mechanics extends to the path integral formulation, where a physical system follows simultaneously an infinity of possible trajectories with associated probability amplitudes for each path being determined by the action for the path. Now, path integral formulation should yield unambiguous, non-singular solutions; which they don’t. To modify the action such that these calculations yield applicable results, the good ghosts are used to break the gauge symmetries and make things right.

So every gauge field has an associated ghost, and where the gauge field acquires a mass, the associated ghost field acquires the same mass in some cases.