23 March, 2007

What is time?

Have you ever spared a thought to this, seemingly "trivial" question? It is not as simple as it looks. Time, as we perceive it, is clock-ticks, hours, minutes, days, years, centuries and ages. But, is this really time that is passing?

Well, you guessed it right, it depends on how we define time. If time is defined as "something measured by a clock" then the above hypothesis might be true and you don't need to read all the prolix prattle which follows. But, if we consider time as something which gradually passes, then we have a problem.

Consider an Arrow. its motion is similar to passing of time. Now, according to Heisenberg's Uncertainity principle position and momentum of this arrow cannot be accurately and simultaneously determined (Yes, it is true even for macroscopic bodies!!). And it is true, if we photograph the Arrow, we know its position, but we have lost all the information about its momentum. and if we see an arrow moving, we know its momentum (as a vector), but we can't determine its position !!

Now, its analogy with time. If time is an Arrow. and say the arrow is moving, then we can't say whether we are in Past, Present or Future !!(its position can't be determined). and if we assume that we are in the Present. then Time is stationary (momentum cannot be determined !!). Thus, a fallacy!!

The thing is, we confuse time with relationships. We measure time (lets call it that for the time being:) ) with respect to some cyclic changes like Earth's revolution around the sun or moon's revolution around the earth. Which implies, that if these motions slow down, time will slow down !! ... therin lies the fallacy! .. we don't measure time, we compare ourselves with other activities. This comparison should not be confused with time!

So, there is nothing called time.
Time is just a perception. An imagination of human mind. That explains why time (the colloquial "time", acutally there is nothing like time) seems to pass slowly while we do a boring piece of work and why time seems to fly away when the work we are doing is interesting! Because, clock-ticks is not time, neither is the location of sun or moon with respect to the earth!

Then what is past? what is future?
Past is just an improbable event. i.e. the waves of probability have grew stronger for the Present and weaker for the past. Also, the waves of probabilty are weak for the future. So, future is also an improbable event, as of now.
To understand it completely, well, consider a gramophone record. Assume, the needle is at a particular point playing your favorite song. Well, it just implies that the other parts of the record are improbable and the part which is being played in highly probable (the analogy with past, present and future in simple).
To summarize the above paragraph, well, past and future are nothing but, improbable events. There is nothing called "time" as such !!

Its all quantum mechanics. As true for macroscopic objects as for microscopic!

So, go over the topic again ... What is time? .. does it seem that simple yet??:))

07 March, 2007

Quantum Computing

This is my seminar topic this year. And the most promising new development in the field of computing.

Today the processors are growing faster and faster. But, there's a limit to the speed. A given mass of material cannot perform more than certain calculations. This puts us into a jeopardy. How will we cope with the future requirements ? The answer suggested was PARALLEL processing. But, again traditional computers proved grossly inefficient in implementing the concept. Scientists were in search of something that was "inherently" parallel in processing .... and the ans came in the form of "quantum computing".

Quantum computing emerged from the fact that the processors will grow so small that their elements will be of the size of an atom. Then the classical laws will be rendered meaningless and quantum laws will come into picture. quantum bits - popularly known as qubits - can store 2^n values SIMULTANEOUSLY, where n=size of register. Thus, the inherent prallelism!

Thus, 2^n computations can proceed simultaneously in a n-qubit register. This massive parallelism has gripped the imagination of the scientists world over!

But, the main problem with this field is, as a renowned scientist summarizes
"My students don't understand quantum computing, because i don't understand it"
Such is the intricacy of the subject that even those working in the field can't confess to have complete knowledge of the topic! Also, most of the technology required to implement a quantum computer is rather non-existent.

All in all, quantum computing is NOT the near future. But, in the long run quantum computing will certainly cause revolutions in the quantum field !! ... It will change the way we compute !

GRE : why when and how ?

GRE : Graduate record examination
This is a must exam alongwith TOEFL (which is also compulsary to apply to US universities for higher studies.

The typical question asked today is "Why US? Indian engineers are earning enough, why go to US?" (This post is only for engineers, others shoooo :) ) ... The reason is, the US education system induces some practicality in you. + You have a chance to become independant i.e. live on yourself. Also, although software engineering is a booming field, there are bound to be recessions and your MS degree in US will help your boss NOT to sack you:).

When ? : there is no restriction by ETS (the GRE conducting body) as to when can appear for GRE. But, considering our own benifit, I suggest you should appear for GRE in your TE (that too, the month of March. March because it is believed that the examination is a bit easier then). TE because, you'll need atleast a year to complete all the formalities : GRE score, TOEFL score, VISA, application to universities etc). So, you can leave for USA as soon as your BE examinations are over. Thus, you don't end up sitting at your home for a year straining your father's income:). If you are NOT sure whether you will clear all subjects in TE or BE, then also, it is suggested to appear in TE only, because GRE score is valid for 5 years.

Classes : I don't know about others, but Dilip Oak's is a good option if you are a puneite. But, again classes are not that much of a help. I suggest, buy out the DOAK's material and prepare on your own.

Books and other resources :
The ultimate guide will be Barron's book. A nice work. You can also go for, Princeton or Kaplan's guides. Besides, there's a lot of material available online.
You can also download some from,
and if anyone needs anything more, well you can contact me. I pride myself with an awesome GRE collection.

Required score :
for computer engineers anything above 1300 will be called decent.
One can easily score 750+ in the quantitative section. So, you are just supposed to scrape in 550 odd in verbal which won't be a problem.
Also, recently Analytical writing scores have gained importance. try to get atleast 8 out of 12. Again this is NOT at all difficult.

Final words :
Anyone readin this post now would probably appear in the new syllabus. So, beware there are only Reading Comprehension and Sentence Completion type questions. RCs are hell. So, start reading now. You need to have a good vocabulary to understand the RCs and attempt the SCs. So, taking a look at the Barron's list will still be a good idea (although, ypu won't need to learn the words as you needed to do in the OLD syllabus)
Plus, the new syllabus will be a 5.5 to 6 hours ordeal. So, get your concentrations up too.
And, Quantitative and Analytical sections are unchanged, so, NO problems on that front.

(Add a comment if you found this useful or if you need further information.
Best of Luck in your endeavour)