Aeschylus

All that you need to recognize is that gamma is undefined when u = c.

There's also the problem of defining particles as energy, as all particles are energy to some extent.

Accelerated frames of reference can still trip up professional physicists, for example there are still some physicsts who believe that special relativity cannot handle accelerated frames of reference.

http://www.webster-dictionary.org/definition/matter clearly photons would fall under this definition. The dividing line is not clear, as though a single photon does not have mass it is possible for a system (when considered as a system) of photons to have mass.

Obviously it depends on your level, but if you don't know the procedure you can be tripped up easily as (excepting general relativity) the normal laws of physics (i.e. those that appply to inertial frames) don't always apply to accelarted frames.

Well I can think of an exmaple: when counting the mass in the universe photons are often included under the heading 'baryonic matter'; of course as well as not strictly being matter, they're not strictly baryonic either!

It depends on the level, accelrtaed frames of refernce are opften apt to trip people up. But then again I just say: 'd'Alembert!'

Define matter. If you were to look in a physics dictionary you'd probably get something along the lines of something with the property of mass, in this case a photon isn't matter because it doesn't have mass. However that is not the only definiton that is used. Photons are photons, the descriptions of 'matter' and 'energy' in this conext are probably too vague.

In relativity the question simply does not make sense, there is no way of defining a frame of refernce for an observer travelling at c. In other words all relativity says is that this is impossible and it doesn't say what were to happen if it were possible. Of course particles can travel fastre than light thorough some medium, in this case Cherenkov radiation is produced, which is in some ways analgous to the sonic boom produced when soemthing breaks the sound barrier.

We are not actually saying that time is the fourth spatial diemnsion, if we were I'm sure spacetime would be Euclidean or at least have the same signature as a 4-D Euclidean metric. Spacetime has a Lorentzian metric and for any observer the spatial diemsniosn and the temporal dimenions are clearly distinguished. To argue that time is not the fourth dimension (infact whether we call it the fourth, first, second or third dimension is really just a matter of semantics, spacetime has four dimensions ) of spacetime is circular, because we define spacetime as the combination of our 3 normal sopatial dimensions with the temporal dimension.

Notice that I was only giving the point of view of those who formulated the EPR paradox, I later said this:

Any particle with on-zero real mass, in any given inertial frame must travel with a speed of less than c, it's a fundamental aspect of the Lorentz group.

Is there a 'true reality'? How does it differ from the reality we perceive? These are fair questions however they are more in the scope of philosphy than physics. In the most formal sense, quantum mechanics predicts the results of measuremnts in terms of probabilty. The orthodox appraoch to QM assigns no physical meaning to the wavefunction only what it predicts when we make a measuremnt. The principle of complementarity, a feature of the othrodox interpretation says that it is meaningless to talk about a particle with both an absolute postion and momentum; QM particles never behave as if any two complementary observables such as postion and momentum both have absolute values. What E., P. and R. did was to come up with the EPR paradox which was a thought experiment which seemingly demonstrated, that if QM is corrcet, the instaneous transmission of information between two spatially seperated locations. Now we know that such instaneous transmission is prohibited by special relatvity, so there must be some 'hidden variables' at work and QM is therfore 'incomplete'. What Bell and Aspect showed that even if there were hidden variabbles at work there still must seemingly be instant transmission of information. These days the EPR paradox is not actually interpreted as the instantaneous transmission of information (something re-enforced by the fact it cannot actually be used to instaneously transfer information), but as the nonlocal collapse of the wavefunction, thus QM is not necesarily 'incomplete'. As said before, the wavefunction isn't conventionally interpreted as having physical existnace only measuremnts are interpreted that way (so you can see why we don't interpret that colapse of the wavefunction as violating relativity). There is no other mechanism than collapse at work in the situation you describe as far as we know.

Because the total number of peer-reviewd papers on stringy theories is in the thousands each year, more than ten times the amount of something like LQG.

Martin, I can assure you that your figures are way too low, the actual number of stringyn papers in those years is nearer to the 1000's.

The high energy streams that come from supermassive black holes which are active galactic nuclei come from their accretion disc (i.e. the matter outside the event horizon).

That's information theory, I imagine it's relevant in genetics but of little relevance here and has no relation to what you said.

What the hell is logical entropy'??? if you invent a concept you have to prove that it should always tend to increase. Now if your talking about organisational entropy which is complelty different, it has nothing to do with 'biological organisation' it has to do with the number of microstates that are equivalent to a macrostates. You cannot use science you don't understand to disprove a theory you don't understand.

It's a postulate of special relatvity that comes from experimental evidence. If you want to no how mathematically objects always appear to travel at c then imagine that that your intertial refernce frame and you observe a space ship travelling with velocity u and another object travelling in the same direction with a velocity v. Someone aboard the spaceship will see the object travel at velocity v' given by the formula [math]v' = \frac{v - u}{1-\frac{vu}{c^2}}[/math] When v = c [math]v' = \frac{c-u}{1-\frac{u}{c}} = \frac{c(c-u)}{c-u} = c[/math]

Inflationary (that is acclerating expansion as opposed to inflation theory) Freidmann-Lemaitre cosmological models are nothing new, they've been around since the start of big bang theory, it's just that they never really tallied with observation.

I think the first form is preferable to the second form, when using exponents: [math]ds^2 = d{x_0}^2 - d{x_1}^2 - d{x_2}^2 - d{x_3}^2[/math] [math]ds^2 = dx_0^2 - dx_1^2 - dx_2^2 - dx_3^2[/math]

The good thing is that anyone can model them, though at uni we used computers that were a little more advanced, IIRC the Sinclair ZX Spectrum 48K had a programme that modelled population pressures bundled in with the original release. Jet Set Willy was more entertaining though.

yep, I remember it's one of the first things we looked at in chaos theory lectures.