Recent content by geometer

As I mentioned earlier, this is a population risk, not an individual risk. This means that in a population of 10,000 individuals, exposure at this level could be expected to result in as many as 8 additional deaths over what would normally be expected. It doesn't mean that your individual risk...

My favorite is "A first course in general relativity," by Bernard F. Schutz. It's an excellent introduction to general relativity. It assumes you have a basic familiarity with special relativity, vector calculus, ordinary and simple partial differential equations.

Complex variable theory is, in my opinion one of the most elegant branches of mathematics. I took two courses in complex variables in college, and loved them both!

There are three major competing theories with regards to the effects of radiation exposure. The one that current exposure and radioactive material cleanup regulations are based on is the "Linear, No Threshold" theory. This theory assumes that any amount of radiation exposure, no matter how...

You're welcome. I figured you were looking for some context for that information.

First, my sincere apologies. Radiation workers are allowed to get 5,000 millirem in one year, not 5,000 rem! Whew! But, that said, an acute dose of 1300 millirem or an acute dose of 5,000 millirem will have no somatic effects. For everyone's information, here is some data on acute...

Finally, from a health risk standpoint, an acute dose of 1300 millirem is negligible. Radiation workers (those who work regularly with radioactive materials) are allowed to get up to 5000 rem per year.

Not so. Any events that appear simultaneous to frame A, will not appear simultaneous in any frame in motion with respect to A.

The failure of simultaneity is an inescapable aspect of Relativity. Consider two space-time coordinate systems A and B. We'll condense the space axes down to one, the x-axis. And, we will call the speed of light 1 just to make things simpler. Now, assume B is in motion with respect to A with...

I agree with Integral - what difference does it make? But, since we arguing trivialities, I disagree with your characterization of the the 3rd Law. It is only peripherally associated with conservation of momentum. In fact, I have seen arguments that Newton's Third Law is the only really law...

Your calculator should be able to give you a value for e^7. I am assuming that you know what e is. Then, using the quadratic formula should give you the correct answer.

For one thing, your equation is wrong. It should be x^2 + x - e^7 = 0 Second, there are methods other than factoring for solving quadratic equations.

The relativity of simultaneity resolution of the twin's paradox is much easier to understand graphically. It basically uses the fact that relativity did away with the idea of absolute simultaneity also. The equation for time dilation falls right out of the definition of proper time if you...

I think what you're missing is conservation of momentum. The momentum of the system before the decay must be the same as after the decay. I think this, along with the fact that you are given the amount of energy released will allow you to calculate the speeds of the reaction products.

ramollari - You're initial analysis of the situation is correct, the fact that at some point in the journey the twin in the rocket has to undergo an acceleration to change direction to come back allows us to determine that with respect to us here on earth, he is the one really moving, so it's...