# Recent content by Gigasoft

As an exercise, write down the Lorentz transformation that corresponds to a velocity v in the x direction, and apply it to the description of a particle moving at velocity w in the same direction. Find the relationship between the resulting x' and t' coordinates. What do you get?
2. ### Electricity and the Earth

Only if you are connected to something which is connected to the negative wire. They don't. The direction of movement is into the positive source. And the direction of propagation of field changes is completely unrelated to the electrons' direction of movement. The current is established...
3. ### Let's say i'm in einstein's elevator

In Einstein's elevator, the field would be uniform. On a planet, it's not. With decreasing distance to the planet, the non-uniformity becomes more and more apparent.
4. ### Direct Product of Groups

- Closure: This is obvious. a *1 c is a member of G1, and b *2 d is a member of G2. Thus, (a *1 c,b *2 d) is a member of G1 x G2 by definition. - Identity element: If e1 is the identity in G1, and e2 is the identity in G2, the identity in G1 x G2 is (e1,e2). - Inverse element: With a *1 c = e1...
5. ### Why can't we use quantum bit entanglement for FTL information?

"The only people that even know what the corresponding entangled particles mean, is the people who are using them and understand what information they represent. No one else COULD know." "The only people that even know what the corresponding letters in the script to Days of our Lives mean, is...
6. ### Why can't we use quantum bit entanglement for FTL information?

No, what you quoted does not constitute a secure means of communication using quantum entanglement. With only 1 bit measured, it is of course impossible to detect that the message has been tampered with or spied on. In fact, it is not even communication, since no information is transferred from...
7. ### Why can't we use quantum bit entanglement for FTL information?

Well, you really don't get it, do you. The entanglement of the particles has no effect on your scenario. Nothing in your scenario requires that the particles are in an entangled state. You could send him a copy of the script to a Days of our Lives episode, and it would serve the exact same...
8. ### Why can't we use quantum bit entanglement for FTL information?

Oh great, so Mr. junior undergraduate's "cryptography" basically consists of assuming that no one knows where you or your friend are, or how you're communicating. Congratulations on completely missing the point of quantum cryptography. Good luck at university. You'll really impress your...
9. ### Why can't we use quantum bit entanglement for FTL information?

Well, then you obviously can't read. As I said, they would capture your particles, as you try to send them to your friend. They would then generate new entangled pairs of particles, and send one particle from each pair to your friend. When you think you're talking to your friend on the phone...
10. ### Why can't we use quantum bit entanglement for FTL information?

Entanglement is of no consequence in your example. It is no different from any other method involving an one-time pad. It is possible for the police to intercept the particles, measure them, and pass them on, without your friend becoming any wiser. Now, you might think, what if I tell my friend...
11. ### Writer's quantum entanglement Qs (help!)

Entanglement can not be used for communication. Whatever happens to system A cannot effect system B in any measurable way. Entanglement has to do with what you can infer about system B based on your measurement of system A. For example, a source can send particles in two opposite directions in...
12. ### Magnetic force and energy

When an object, such as a lump of iron, is accelerated by a magnetic field, where does the extra kinetic energy come from? Does the object become colder, or is it demagnetized?
13. ### Electrostatic potential from the perspective of an electron

No, by touching a wire, a current will flow into you until you are at the same potential as the wire. At this point, the charge that you have acquired is equal to your capacitance times the voltage. With a wire at thousands of volts, you will therefore feel a jolt. It can seen that it is...
14. ### Absolute value of infinity

\lim_{x \to 0}\frac{1}{x} = \left|\infty\right| This expression is blatantly incorrect and shows that the author has a basic misunderstanding of mathematics. What he probably means, if you could write it like that, is: \left| \lim_{x \to 0}{\frac{1}{x}}\right|=\infty But you can't. An...
15. ### The proliferation of mathematics cranks on the Internet

I've noticed on other discussion boards, that there is a surprisingly high number of people sharing a set of similar, unshakeable beliefs that contradict basic thereoms in mathematics and logic. Usually, these include: - 0.999... not being equal to 1, or not existing - That natural numbers...