Nature

Perihelionic Winters !

Winter and Summer are occurring counter intuitively due to valuation in a day long configuration of earth and sun. A few million kms distance change from sun isn’t causing the season, but how exactly we are tilted even at the shortest distance from sun can cause winter. And this stands to change over 26000 years, twice, so winter will sometimes occur due to how we are tilted to the sun, even if we will be farthest away from it, but we won’t be there to experience it.

Interesting planetary facts !

Mars winter and summer would have a wider variation due to Sun’s relative distance being a 17%; variation in radiation is 34% (2 x 17%)

For earth since distance of earth and sun varies from maximum to minimum within 3.4% the variation in sun’s radiation energy is 2×3.4 = 6.8%

Also Venus is far more closer to Earth in most of its actual parameters. (eg inclinations don’t matter, mass and gravity and pressure etc do) But Venus is 31 times hotter than earth on an average and a person would feel 100 times more pressure from the atmosphere above his head. He would burn and crack like a f** fish.

Review of Gravity, the movie, discussions.

A discussion on Space movie Gravity, which I saw recently.

I remember one fact, that concerns, Physics, the roughly 50000 miles an hour (correct?) speed of ISS level debris that was coming, it set me thinking, are they violating the Relativistic Laws? For a while, and then I realize its per hour, not second, (that later would be grossly incorrect, 50 K miles / sec would violate Relativity certainly) that comes out to be 20 km/sec and thats perfectly enough close to what sort of speed, earth, moon, any satellite are typically found with, in our Sun’s Gravity. (in free fall) Even Rocket’s launching requires escape velocity. 11.2 km/sec. So they have clearly done their research on the Physics, as far as I could get in that moment.

Whats Light. A small primer.

A small primer on optical attributes of Light.

Manmohan Dash,

( — largely edited, 18-19 January 2014, originally from; Wednesday, March 27, 2013 at 3:58 pm UTC + 05:30 )

Updated Discourse.

If you ever seem, to be caught up between: they say light always moves at the same speed-c, they keep on harping, why then, its energy so different; we have light of various energy and frequencies. One that are harmful, like x-ray or ultraviolet and one that are quite soft on us all. The answer is there are two kinds of speed, when it comes to vector emissions like light, one speed is on the plane of polarization, giving us the energy or frequency or intensity of light waves, and the other, the speed perpendicular to that plane, that is; the speed at which energy of light is transmitted across the galaxy, its this latter speed, which is slated to be known as speed-of-light (instead of, speed of light’s energy transmission vs speed that determines the energy value of light transmission) and always a constant known as c, whose value is unchanged, as long as a single quantum of light is considered and in vacuum.

Note that vector emission means there are 3 dimensions, in which this wave is created or propagated, light wave, its a plane + a perpendicular dimension to that plane. The plane is called plane of polarization which always contains two fields, Electric and Magnetic field, and the perpendicular dimension is the direction in which the energy of the light wave is propagated, therefore, gives the light-wave-speed; which are again of two definition, the physical or actual speed known as group velocity, and the virtual, conceptual speed of each wave train, known as phase velocity. This definition of phase and group velocity are always to occur; for any kind of waves and not just light wave. So, the light-wave-group-velocity (for a single quantum-of-light, called photon) is always c = 2.99 x 10 (8) meters/second, in vacuum.

Why human eyes are sensitive to only visible light?

“Why Human Eyes Are Sensitive To Only Visible Light”. These processes are arbitrary, which is somewhat more technically referred as “contingency”. Its not just for the case of vision that this arbitrariness is present, but all forms of biological properties. eg A conch shell is spiral in a certain way and this is only specific to the snail-likes. Fur is different for different animals. Arms and limbs are different for different animals. This is because of such arbitrariness which are present in 100s of different ways depending on exactly how a life form develops. ( — We are all describing this on general terms, here in this discussion).

Technically, adaptation has to do with exposure. One has to be exposed to the kind of situation one is borne in. Human beings are not borne deep down, on the ocean bed, but on ground with optimum temperature and other life conditions. So, there has to be optimal amount of heat present. Human Beings can’t survive huge temperatures. But many animals can, so they are exposed more harshly to Infra Red (IR) etc. Its the whole body which evolves and then different parts might evolve differently. [w.r.t. different thermodynamic and other life defining conditions]

Just a wild guess: may be some animals were borne [created by contingent chances] very close to volcanic eruption, eg snakes, which is why they could be sensitive to IR type of vision. etc etc. On planet earth, optical light comes only from Sun, (in its profusion, can turn off the sun during night or moon some nights and its total darkness). This sun-light in optical radiation window is extremely intense in visible spectrum but with IR spectrum its intense only during summer. This intensity going from one place on planet earth to another can vary between say 10% – 60% during a year. That means the likelihood of birth can be reduced by that factor towards IR exposure, if it were to come from sun but not from volcanoes. The actual condition on earth might …