# Aeschylus

Senior Members

241

1. ## Equations

e = mc^2 is Einstein's, the Lornetz transformations and Lornetz-FitzGerald contraction and time dialtion aren't. What Einstein did was to to gather up all these sets of equations and but them into a single self-consistent theory in which they can derived from more basic axioms.

4. ## Empty time/space.

Well small things please small minds. The term "spacetime continuum" refers to a mathematical construct, not some vague cod-philosophical concept.

Lukis Whayn
6. ## Unified Theory

Very good, now go away and learn some physics.
7. ## Equations

It should be: $t = \gamma t_0$ etc. The formulas for time dialtion and lenght contraction were not Einstein's. The formula for Length contraction (usually known as Lorentz-Fitzgerald contraction after the two phycists that discovered it independtly) precedes the theory of special relativty by 10 years, I believe time dialtion came only a yera before the STR. All these equations can be derived from the Lorentz transformations (indeed the formulas for Lorentz-Fitzgerlad conbtarction and time dialtion really are just incomplete versions of the Lorentz transformations), the first and third ones are very easy to derive. The second equation, these days wold be considered to be wrong as mass m is taken as the rest mass and thus invariant. E = mc^2 is not particualrly easy to derive, but can be derived by considering the absrption of a photon.

9. ## Using theories and proofs. Why couldnt there be an end to numbers?

In that case you are certianly not talking about the real numbers.
10. ## Using theories and proofs. Why couldnt there be an end to numbers?

Buy a book on analysis. The real numbers are closed under additon so for any x, x + 1 is also a number of the rela numbers, further x < x + 1, therefore there is no largest real number (of course it's not enough just to say this, it must be proven from the axioms of the real numbers, which is why I suggest you buy a book on mathematical analysis).

13. ## How do you spell Occam/Ockham.....

It's usually called Occam's razor, which is the way that the French spelt his name. The person for who it is named is usually called William of Ockham as that is how the village is spelt nowdays, both are acceptable spellings. You have to remember that in the days of William of Ockham there was no such thing as standardized spelling and in England manuscripts were more often written in Latin or French than English.
14. ## Time travelling

http://arxiv.org/pdf/astro-ph/0011070
15. ## Time travelling

:Sigh: it's a genral relativistic effect and what do you mean by the 'other way'? Recession velcoties may be greater than c as they are not due to local cooridnate velcoties, but the expansion of the universe itself. Davis and Lineweaver (2000), showed that there must be galaxies in the observable universe with recession velocities greater than c for any reasonable cosmological model.
16. ## Time travelling

It's recession velocity is greater than c. Y'know you can google yourself it's not as if there are not a wealth of websites about this.
17. ## Time travelling

Think carefully what you mean by the universe expands at such and such a speed. Really the rate at which the universe expands is not a speed, it's measrued in units of s^-1. You can certainly talk about recssion velcoties, which may certainly be greater than c (infact the recession velcoties of the furtherest galaxies are greater than c) but these are dependent on distance, so they're not a measure of how fast the universe expands as a whole.
18. ## Point of light travelling faster than light

Not strictly true as the two photons do not have relative speeds as they do not have refrence frmaes. Taking the limit of the compostion of velcoties law you actually get an answer of c.

20. ## Time travelling

I am tlaking about the fact that the relative rate at which clocks 'tick' is itself relative. a is correct for a's frame and b is correct for b's frame there is infact no contradiction.
21. ## Time travelling

It does work, because the rate at which they tick is relative. if a and b are both travelling with constant velcoity there is symmetry between them,howvere when the clock was flown around the world it was subject to acceleration, so the two obserevrs were not symmetric. It is easy to show that an unaccelarted observer experinces more time between two events than an accelarted observer.

24. ## how do i work out the area of a circle without a calculator?

If your asked to find the raidus of a circle of say radius 9m, then you should alewyas express your answer as 81*pi m^2, of course if for some reason (I relaly can't think of any reaosn though) you need to know wherre it approximatley lies on the real number line then you would approximate pi.

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