All variable used are positive.
Suppose the state of universe in one instant of time x is f(x).
Is it possible to find a t where f(x+t) = f(x) for all x?
I had this question in my mind today. because if that is true, then travel back in time can be just traveling to future.

But second law of thermodynamics says it's not possible.

Humm... but that law also means we are all going to be converted into entropy... and our existence would be really... eventually... meaningless.

Olympics!!
I don't care about sports.

What exactly make people Chinese?

I have asked many people and most don't have the same definition for Chinese and some don't even have a definition for Chinese. Even Wikipedia don't know if for sure!

Some common interpretation of Chinese:
1. Citizen of PRC and/or ROC
2. People whose offspring of Chinese people
3. People whose offspring of Zhonghua minzu

1. I can't believe all Chinese citizen can accept if a Japanese(how to define Japanese??) person become Chinese citizen and refer himself as Chinese.
2. The second one is clearly a recursive definition without the base case. and define a base case is not likely to fit usual needs.
3. It's a bit better because Zhonghua minzu is more rigorously defined by ethnicity, but the definition make people say "WTF". Some people with Russian heritage are part of Zhonghua minzu, but not others.

Is there a function f(p) that result 0 when one is not Chinese and 1 when one is Chinese?
There is no such universal function.

Assumptions:
At least one can find 2 people have different views on what is considered Chinese.
Set are determined by characteristics.

My theory for the set of Chinese people.
There is a certain set of characteristics to determine a set. Call the set of characteristics C, each element c. One of the element is excluded from the set(see below) for details.
W(c) is the weight of an c, can be negative.
V(c,p) equals 1 or 0. 0 means the person p in consideration doesn't have the c.
A person is considered to be Chinese when
Sum of W(c)*V(c,p) > x (which is THE characteristic of the set Chinese, and it's not part of the set C.)
1. W(c) is different for each individual because different people have different views
2. so is x.
A person at a different time(1 second ago) is considered different as that person. so A can think B is Chinese today, but it's not Chinese tomorrow.

Conclusion:
Chinese people cannot be rigorously defined without first find W(c) and x, which depends on the person who evaluates if a person is Chinese or not.
There can only be a function f(p1,p2) that result 0 when p1 think p2 is not Chinese. and 1 when p1 think p2 is Chinese.

But that doesn't mean there isn't any universal Chinese, there might be a person p, where f(x,p) always result 1, where x can be any person. But if such p doesn't exist. Then if we take the intersection of all the considered Chinese for x, we get a empty set.
Then that means there are no such thing as universally recognized Chinese people. Chinese people don't exist!
Of cause, one can define a universally recognized Chinese person is recognized as Chinese by x% of the population, but now, x is depend on different people, and thus require another level of universally recognized universally recognized Chinese people... and it will go on and on...

Can anyone prove a universal Chinese person exist when universal = all population in the world recognize him as Chinese at the year 2008. Btw, the word Chinese here has no meaning, it is a symbol in a formal system refer to a set that no one can define rigorously.

Thus Chinese people is a ambiguous term. It's just an isomorphism for something else we can't define.
Maybe this can be generalized to almost every word in existence.

I thought of something today:
"I love some girl on girl action."
and so, I made it into a image:

can be interpreted in many ways
hot girl on girl action is hot
hot times girl over girl equals to hot
A hot girl divides another girl and it becomes home.
I'm creative!

MIT freshman application out tomorrow!

Data From Salary.com

Y axis is amount of money in dollars
X axis is the percentile, only plot 3 points, 25th, 75th and 90th.
A line with the lowest starting point in each color means Instructor of [Insert Major].
2nd lowest is Assistant professor of [Insert Major].
3rd lowest is Associate professor of [Insert Major].
then it's Professor of [Insert Major].
Last one is Dean of [Insert Major].

From what I can see, clearly, the safe major to chose is computer science. Pay is good even for a CS instructor(around the same pay as a associate professor in philosophy, damn!

Philosophy is the most unsafe. Unless one can become a professor and manage to get into the very top, it's better to select the other 2.

Math is good. Money increase is steady compare to title.
Math professors can earn more than dean of mathematics.

Dean of medicine totally owns everyone else in colleges. The 25th percentile is already outside this graph.(almost 300K)