between3and26characterslon

First of all the frame of reference in which the observation is made is one we are at rest in, the speed of light measured in this frame is always c, regardless of which frame you choose to make your measurement in. If light travelled relative to a universal frame we would measure the speed of light to be other than c in the frame in which we make the measurement. This is the principle of relativity. You are the one making unecessary additional (universal) frames. Second, you ask "if two photons are travelling side by side how can this not lead to the conclusion that they are travelling relative to a universal frame" My question to you would be how does it lead to the conclusion there is a universal frame? Does it lead to any conclusion? Can you disprove a negative or just collect enough evidence to show a diferent answer is more likely? Thirdly, This universal frame you are insisting on must by definition be absolutely at rest, what is the frequency of light in this frame. We know the speed of light is constant in all frames but its frequency changes depending on your motion relative to its source so what would the frequency of light be in a universal frame, zero or infinite? (keeping wiht the theme) Fourthly, the point everyone is trying to make is that two photons travelling side by side does not lead to the conclusion there is a universal frame nor does it lead to the conclusion there is not a universal frame... But everthying else we know tells us there is not a universal frame, as many people have explained in many different ways.

The impact of clinical trials is far far less than the impact of not doing them!

My question would be (amongst the many many others) two objects of the same mass in the same gravitational field for the same time will experience the same force acting upon them. If one of those masses is moving (i.e the one on the train) it gains mass so breaks the string and kills the cockroach, however this moving mass is time dilated relative to the Padre therefore it is not experiencing the gravitational force for the same amount of time. its gain in mass and reduction in time would probably exactly counteract each other and so the string would not break. Is the force acting upon it therefore the same in both frames? Edited for spelling

This might be complete nonsense but here goes: An object flies past you at 90% SOL, from your POV it is shortnened in its direction of travel. That is to say, a standard unit length (SUL) travelling at 90% SOL along the x coordinate of your frame of reference will appear to you shorter in its direction of travel than a SUL aligned in the same direction but stationary relative to you. If it was the SUL that got shorter then it would be shorter in its own frame of reference which is clearly not the case, so it must be the frame the SUL is in that is shortened in which case it is space that is shortened. So is it the case that an area of space, billions of lightyears away, that is receding from us at approaching the SOL will to us appear shorter in its direction of travel and will appear to show time running slower in it. With that in mind back to the OP and the expanding universe If the Universe is expanding at the SOL would not therefore the furthest observable parts be shortened to zero length in the direction of travel (i.e. away from us) and would not time in these places stop ticking as observed by us. So relative to our position the edge of the observable Universe is not moving.

I'm no expert but I disagree with this statement. Studies of type 1a supernovea show that the farther distant an object the faster it is moving away from us but this only implies objects are accelerating away from from us, it does not prove it. Unless there is evidence that a known object is moving away from us measurably faster now than at some point in the past I don't think we can conclude an accelerating Universe. Maybe it's my lack of understanding, I am open to evidence or explanation.

At the risk of entering into the realm of philosophy what is meant by "detection of the location of the particle". Is observation or detection a conscious thing per se or does it simply mean an interaction? If so why does the electron's interaction with gravity and the Earth's magnetic field not affetc the result?

:bold mine: You must NOT apply for both twins. It only works for an inertial observer, the twin that accelerates is not inertial. http://www.einstein-online.info/spotlights/Twins

In order to observe the electron it has to ineract with something (a magnetic field for example, or, the back wall of the apparatus) if this interaction occurs BEFORE the electron goes through the slits it will only go through one slit as a particle. If however there is no observation of the electron before it goes through the slits it goes through as a wave. The remarkable thing is that the electron is always in the Earths gravitational field and magnetic field so is always interacting with something so it seems it is conscious observation that gives rise to the difference between diffraction pattern or not.

A simple answer might be: If you were to raise a bucket of water by a few meters you have put work into the system. If you allow that water to return to its' original position you get that work back. Now if you were to take a load of matter, I mean like a lot, and blew it up in a collosal bang say, or a huge/massive bang or maybe a "big" "bang" then, in the same way as the water, you have already put energy in and are now getting it back.

Is that another way of saying gravity?

Glass is transparent to visable light but relatively opaque to UV, This is because the electrons sorrounding atoms can only have certain energies and therefore the difference between energies is a specific amount. So in glass UV radiation has exactly the right amount of energy to cause an electron to jump a whole number of energy levels so it CAN be absorbed. Visable light however has only sufficient energy to cause an electron to jump a fraction of an energy level and, as this is not possible, it CANNOT be absorbed. So different materials are either transparent or opaque to different wavelengths of light depending on the allowed electron transitions in that material

I've not read all of the replies here so if this has been covered I apologise. But what would propell this ship forward? This 'warp bubble' would only appear to serve as a way of isolating the ship from the relatiavistic effects of FTL travel, this I understand but if the space around the ship is isolated from the rest of space by what mechanism is the forward propulsion of the ship/warp bubble system controlled? EDIT: spelling mistake

Anyone else notice how Mohika has only posted once on this thread, I wonder why that is... ... I can't speak for Mohika but personally I get quite irritated that when someone asks a simple question the answers posted are not always in the same vein, rather some people just try to dump every concept, long word, graph, equation etc... etc... they can think of in an attempt to show off that they know more than the next person essentially avoiding the original question all together. Why not try and converse with the OP and draw out what they do and don't know and provide an answer in a way that might educate instead of irritate. Rant over. I have asked the same question as Mohika; if we are seeing objects in the past all we can say is what they were doing. Q: What would we see if the universe suddenly stopped expanding and started contracting? Let's say the most distant objects start contracting first. We would still see an expanding Universe, we would have to wait for billions of years for the light from the now contracting galaxies to reach us. As far as I know no single object has been measured at different times and has been seen to accelerate. Why is it not true that an object we see that's 10bn LY's away is how it was 10bn years ago and therefore all we can say is 10bn years ago it was receding at speed x

Hence the term visable universe Or you have a set of laws that describe how things behave and a set of theories which give rules to describe a mechanism that causes the behaviour. By knowing these laws and theories you can predict future events and past events. Looking at past events you reach a point, about 13.7bn years ago beyond which you can not know anything. So this is really a battle of reasoning and not preference. ...and viola, you have just ascribed a property to something of which you could not possibly have any knowledge. Time before the big bang is meaningless.

Assuming a uniform density approximately 1/8th you would weigh at the surface. You only need consider the radius of the sphere beneath your feet so if you were standing on a planet the same density as Earth but half the diameter you would weigh 1/8th what you do on Earth. The volume of a sphere has the term r3 in it, if r is twice as big r3 is 8 times bigger

It's the fact you're measuring half life that makes it exponential, if you were to measure the number of decays per thousand atoms you would find it is constant regardless of how much you start with i.e. linear Or to put it another way, 1/2 of 1/2 of 1/2 of 1/2 of... etc, is exponential

I am aware of this

You can not measure the speed of something in its own frame, it is always at rest in its own frame. You measure the SOL in an inertial frame by calculating distance over time which will always = c (in vacuo) With this in mind your post is nonsense (no offence)

Type 1a supernovae occur when a white dwarf star accretes mass from its binary star until it reaches a point when it explodes. This always happens when the white dwarf reaches a particular mass so the resulting supernova is always the same brightness. This is the standard lightbulb and from this you can work out how far away an object is i.e. 2x distance = 1/4 brightness. If you were to measure the red shift of this supernova you would find a correlation with its distance. The distance can be calculated from the apparent brightness and inferred from the red shift. So you work out how far away objects are, then measure their red shift, find the correlation and now you can estimate an objects distance just from its red shift.

The best explanation I heard is it's the stuff stopping everything happening all at once

So does GR make the assumption that r=0 or is it derived from GR that r(must)=0? If so; How valid is this conclusion if we can't prove it in reality? i.e. actually measure the radius. Also (and I think I've asked this before) How does gravity extend beyond the event horizon? If I had an indestructable stick and poked it into a blackhole I would not be able to pull it out again for to do so would require the end inside the blackhole to travel faster than light. Or, if a blackhole is there and we know it's there then we have some information, how does this information get from the singularity to the event horizon to us?

As you mention black holes I have a question. Please keep in mind my knowledge of maths is very limited, also, this question might be utter nonsense for reasons I don't understand. However; The centre of a black hole is a singularity and at this singularity our understanding of physics breaks down because things tend to infinity. But why is the centre a singularity, why isn't this singularity also governed by the uncertainty principle? Is it therefore not a singularity? **http://www.youtube.com/watch?v=hydDhUNvva8** in the first minute of this vid i.e. does r not = 0 can you not just throw some uncertainty into the equation

"Argumentum ad tedium" I'm guessing that localisation is frame dependant also. If you have a coordinate system that is moving at constant speed and is not accelerating it behaves as though it is at rest and is called inertial frame. This is the principle of relativity. More succinctly; the laws of physics in a coordiate system with constant motion (no acceleration or rotation) are no less simple than a coordinate system at rest. If you have a photon source in an inertial frame and this source is at rest relative to this inertial frame then an emitted photon will have a specific frequency within this frame, let's call it x. It has freq x when emitted, freq x throughout its journey (ignoring universal expansion for now) and if you have a receiver which is also at rest in the inertial frame it will record freq x. If you have a receiver rapidly travelling towards the photon source it will measure freq > x and if you have a receiver rapidly travelling away from the source it will record freq < x. Both of these new receivers are moving in your original frame but are stationary in their own inertial frames. So if your receiver is moving towards the source then not only will it measure freq > x but it is true to say that relative to its coordinate system the photon was emitted with freq > x and had freq > x throughout its entire journey. I would conclude therefore that localisation is also frame dependant. It seems to me that you are thinking the photon has an absolute frequency which changes depending on how you are moving relative to it and what you are asking is what is its "proper" frequency. This would only be true only if there was and absolute frame of reference... but there isn't. The frequency with which a photon is emitted, travels or is received is relative to the frame you are in when these phenomina occur.

Before measurement it is relative also, there is no absolute frame of reference.

Didn't realise this question had been asked so many times before. The photos I've seen show fingers of light eminating from the double slits and the explanations I've read describe a diffraction pattern of light eminating from the double slits when smoke is introduced to the experiment. So a particle is only a particle when it's interacting with something and when not interacting it's a wave?