Wednesday, April 21, 2010

What are active networks?

Radical design paradigm which advocates carrying programs
+ data as part of a packet. Routers are said to be active
in such a network since, each of the routers will be executing
the code in the packets instead of just forwarding or routing
them as in a conventional network. The routers should support
secure execution of code without which the entire infrastructure
could fail. Techniques have been provided for securely fingreprinting
the code to prevent spoofing and malicious code execution.

Largely not adapted in the real networks due to the huge change in

Tuesday, April 20, 2010

Summary on Supermassive black holes

  1. They are the largest form of black holes found in the universe.
  2. Super massive black holes (SBHs) were first believed to be present because of bright quasars observed in the center of active galaxies (the ones which had not cooled down yet). Since the black hole cannot be seen (due to its ability of not even letting light out of its gravitational pull), scientist looked for the signs of their gravitational pulls to detect their presence. It seemed that they were at the center of active galaxies initially. Instead they found the first supermassive black hole in the andromeda galaxy which is very much dormant and closest to earth.
  3. This was followed by subsequent discoveries by the hubble and other telescopes that black holes were present in almost all galaxies including our very own Milky way!
  4. They also found that the mass of the SBH is directly proportional to the size of the galaxy and also proportional to the speed at which stars were moving at the edge of the galaxy.
  5. This helped them link SBHs to the origin of galaxies.
  6. The SBH at the center of our galaxy is far off and is relatively small and somewhat dormant. Hence we should not be technically affected by the SBH.
  7. Instead we might be affected by the collision of our milky way with the andromeda galaxy which is moving at us with a great speed. The impact is expected to happen in a few billion years.