At the time of the big bang how big was the singularity estimated to be?

Answer 1

A Singularity does not have 3 Dimensions, so no Volume to be Measured. The Singularity would be a 0 Dimensional object, as 1 Dimensional Strings were a little time off.

The Concept of Size breaks down at the Extreme Conditions that the Primordial Singularity represents. It is the Whole Universe, in theory. Mathematically, every calculation approaches Infinite.

Perhaps, someday, we Mortals will have a way to Examine such an Event. Until then, it is a Hypothetical Exercise, and open to Reinterpretation as our Understanding grows.

Remember the Formation times that are discussed are around 10^-43 sec to get the Proper Dimensions to form, and there is No Way to know what came Before the Singularity, but the Singularity is Gone as Time begins. A lot changes in the Short timeperiod that follows:
http://en.wikipedia.org/wiki/Timeline_of_the_Big_Bang

Simplest Answer: Size 0 (with lots of room to improve)

Answer 2

According to the latest cosmological models, there was no singularity that originated the Big Bang, because the math just doesn't work: Among other things, the temperature of the singularity would have had to be infinite which is logically impossible.

String theory provides at least two solutions to this problem:

1) String Gas Cosmology, wherein the universe began as a very dense and very hot soup of strings.

2) The Universe has actually been around forever, trapped in a multi-dimensional brane. Our brane occasionally bumps into other ones and the energy released is gigantic. From inside our brane, the energy and resonance from such a collision looks like an expanding universe that started from a . . . Big Bang.

So the answer to your question . . . well . . it's complicated.

Answer 3

No size, it's a singularity. However much mass, it was at infinite density, so it has 1/infinite volume. A singularity is not a black hole, the latter has a radius because that's the distance at which light can no longer escape. A singularity forms in the middle of a black hole, and it again has infinitely small radius.

Answer 4

Infinitely small. A microsecond BEFORE the Big Bang.

Answer 5

singularity means infinitely small

Singularities are points at which the mathematical solution to the space-time equations are undefined.

A region of zero volume and infinite density where the warping of space-time is infinite and the laws of physics break down

Answer 6

As it was a singularity and size is relative there is nothing to measure it against so the question becomes meaningless.

Answer 7

Science describes it as a point with no radius.