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Varun's Blog - At the Speed of Light !

A fact is a simple statement that everyone believes. It is innocent, unless found guilty. A hypothesis is a novel suggestion that no one wants to believe. It is guilty, until found effective. ~Edward Teller

A very warm welcome to my th reader.Why speed of light ? Well, the aim of this blog is to reach the impossible by exploration and scientific fervor. Exploration never ends, knowledge never dies but Speed of Light can be achieved ....

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Tuesday, March 27, 2007

The Fermi Paradox

The story goes that, one day back on the 1940's, a group of atomic scientists, including the famous Enrico Fermi, were sitting around talking, when the subject turned to extraterrestrial life. Fermi is supposed to have then asked, "So? Where is everybody?" What he meant was: If there are all these billions of planets in the universe that are capable of supporting life, and millions of intelligent species out there, then how come none has visited earth? This has come to be known as The Fermi Paradox.

Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire Galaxy. Within a few million years, every star system could be brought under the wing of empire. A few million years may sound long, but in fact it's quite short compared with the age of the Galaxy, which is roughly ten thousand million years. Colonization of the Milky Way should be a quick exercise.

So what Fermi immediately realized was that the aliens have had more than enough time to pepper the Galaxy with their presence. But looking around, he didn't see any clear indication that they're out and about. This prompted Fermi to ask what was (to him) an obvious question: "where is everybody?"

Also, if one considers the amount of time the Galaxy has been around (over 10 billion years) and the speed of technological advancement in our own culture, then a more relevant point is where are all the super-advanced alien civilizations. Russian astrophysicist Nikolai Kardashev proposed a useful scheme to classify advanced civilizations, he argues that ET would posses one of three levels of technology. A Type I civilization is similar to our own, one that uses the energy resources of a planet. A Type II civilization would use the energy resources of a star, such as a Dyson sphere. A Type III civilization would employ the energy resources of an entire galaxy. A Type III civilization would be easy to detect, even at vast distances.

This sounds a bit silly at first. The fact that aliens don't seem to be walking our planet apparently implies that there are no extraterrestrial anywhere among the vast tracts of the Galaxy. Many researchers consider this to be a radical conclusion to draw from such a simple observation. Surely there is a straightforward explanation for what has become known as the Fermi Paradox. There must be some way to account for our apparent loneliness in a galaxy that we assume is filled with other clever beings.

While interstellar distances are vast, perhaps to vast to be conquered by living creatures with finite lifetimes, it should be possible for an advanced civilization to construct self-reproducing, autonomous robots to colonize the Galaxy. The idea of self-reproducing automaton was proposed by mathematician John von Neumann in the 1950's. The idea is that a device could 1) perform tasks in the real world and 2) make copies of itself (like bacteria). The fastest, and cheapest, way to explore and learn about the Galaxy is to construct Bracewell-von Neumann probes. A Bracewell-von Neumann probe is simply a payload that is a self-reproducing automaton with an intelligent program (AI) and plans to build more of itself.

Attached to a basic propulsion system, such as a Bussard RamJet, such a probe could travel between the stars at a very slow pace. When it reaches a target system, it finds suitable material (like asteroids) and makes copies of itself. Growth of the number of probes would occur exponentially and the Galaxy could be explored in 4 million years. While this time span seems long compared to the age of human civilization, remember the Galaxy is over 10 billion years old and any past extraterrestrial civilization could have explored the Galaxy 250 times over.

Thus, the question arises, if it so easy to build Bracewell-Von Neumann probes, and they has been so much time in the past, where are the aliens or at least evidence of their past explorations (old probes). So Fermi Paradox becomes not only where are They, but why can we not hear Them and where are their Bracewell-von Neumann probes?

- Rohan Warnmallya


Tuesday, March 13, 2007

Direction Of Time

The concept of TIME-EMIT – Total Increase Of Mutual Energy raises many questions in our minds. The laws of Science do not distinguish between the past and the future. The arrow of time always points from a direction with less randomness towards a point having more randomness. There are three arrows of time :

:. Thermodynamic arrow of time
:. Psychological arrow of time
:. Cosmological arrow of time

According to thermodynamic arrow of time, the direction of time is in the same direction as the increase of entropy. Psychological arrow of time has a definite direction. This is a direction in which we feel time passes. This is a direction in which we remember our past and not the future. Finally, cosmological arrow of time has a direction in which the universe is expanding and not contracting. Speed of light can be considered absolute but TIME is relative. This gave birth to theory of relativity !

The bamboozling questions that arise are :-
.:Q:. Will this arrow of time ever change its direction?
.:Q:. How would the state of our universe get affected?

The biggest problem is that universe is continuously expanding and evolving. In accordance to this evolution, we need to update and develop our laws and theories also. One cannot predict the beginning of the universe because laws fail at the Big Bang singularity. Classical theory ceases to hold good for the universe when the curvature of space-time becomes large because then the quantum gravitational effects become important.

The laws of science are unchanged under the combination of operation – C, P and T

C – changing particles for anti-particles

P – taking mirror image

T – reversing direction of all particles

Overall, we have to run in the backward direction. The laws of Science that govern the behavior of matter under all normal situations are unchanged under the combination of two operations C and P. Life would just be the same (as on earth) on a planet in our celestial neighborhood having inhabitants, which are mirror images of us and are made up of antimatter.

Contracting phase of the universe doesn’t favor existence of intelligent beings. Hence, we would never have the opportunity to ask or observe the reversal of direction of the arrow of time.


Saturday, March 03, 2007

Total Lunar Eclipse, 3rd March, 2007

Penumbral Eclipse : 20:18:11 UT
Partial Eclipse : 21:30:22 UT
Total Eclipse : 22:44:13 UT
Greatest Eclipse : 23:20:56 UT

Total Eclipse : 23:57:37 UT
Partial Eclipse : 01:11:28 UT
Penumbral Eclipse : 02:23:44 UT
The moon will turn reddish brown on Saturday night as it passes behind the Earth's shadow in the first total lunar eclipse in three years. Light from the sun will still reach the moon after being refracted through Earth's atmosphere, giving the moon an eerie dark reddish tinge.

The eclipse will be at least partly visible from Asia to the Americas, although those in Europe, Africa and the Middle East will have the best view. Earth's shadow will begin moving across the moon at 3:18 p.m. EST Saturday, with the total eclipse occurring at 5:44 p.m. EST and lasting more than an hour. Alaska, eastern Australia and New Zealand will miss the show altogether. In India, Maximum eclipse is at 4:50 am on the 4th in New Delhi. In Singapore, the Moon enters the totality region at 6:13 am.

Astronomers or photographers can send me their pictures and I will feature it on this blog.

The next total lunar eclipse will occur Aug. 28.

Sources : NASA Website
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This is science !

When you are speaking to technically illiterate people you must resort to the plausible falsehood instead of the difficult truth.

Photos of Comet Mcnaught !
Astro-photographer? Send your photos to pics@exploreuniverse.com and have them featured on this blog with your name. Comet Mcnaught : Pictures taken with Nikon D100 on 19/1/07 from Manning Point, northern NSW, Australia by Mr. Peter Enright.
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