Re: Is the universe still a singularity?

Your question seems to come from Lorentz contraction and time dilation in special relativity. That theory shows that, as body A approaches the speed of light, the length of body A gets smaller to outside observers, and its clock slows down. The “relative” part of relativity means that it sees the world around it to be shorter as well, as you said – because, according to body A, the world is flying by it just as fast! This is a standard, accepted, piece of physics, and length contraction and time dilation have only minuscule effects unless one moves quite close to the speed of light.

Formally, if we try to apply the equations of special relativity to a body that is moving at the speed of light, the equations show that it has zero length, and that its clock doesn’t move at all! I assume that this is what you mean by a singularity – to a photon moving at the speed of light, this seems to say that the world has zero length and that no time ever elapses!

However, this isn’t strictly true. To derive the equations of special relativity, we need to assume that the objects move slower than the speed of light. So the equations that we usually write down for special relativity actually don’t apply to photons. In fact, special relativity shows that it takes an infinite amount of force in order to accelerate any object to the speed of light – and since that is impossible, at least so far as we know, no object can be made to move at the speed of light (however, we can get it arbitrarily close with a large enough force).

So photons are “born” moving at the speed of light, but nothing else can ever move at that speed! There is no theory about how photons treat distance or time (and in fact the concept of time is one that we are trying to understand much better through string theory), but they do not see the universe as a single point, because in that case one would not be able to describe their movement from creation to destruction (such as absorption by an atom). So, in a sense, the problem you raise is one that may exist…but one that we never have to worry about!