How is the universe flat?

Question

I read on the cover story of Yahoo that the universe is flat. Can you explain this to me in more detail please? I thought the universe had no shape and if anything was round.

Answer 1

In a flat universe, all of the local curvature and local geometry is flat. In general it can be described by Euclidian space, however there are some spatial geometries which are flat and bounded in one or more directions. These include, in two dimensions, the cylinder and the torus. Similar spaces in three dimensions also exist.

Answer 2

A 'Flat' Universe which is just a theory. In a flat universe, all of the local curvature and local geometry is flat. It is generally assumed that it is described by an Euclidean space, however there are some spatial geometries which are flat and bounded in one or more directions. The alternative two-dimensional spaces with a Euclidean metric are the cylinder and the Möbius strip, which are bounded in one direction but not the other, and the torus and Klein bottle, which are compact. In three dimensions, there are 10 finite closed flat 3-manifolds, of which 6 are orientable and 4 are non-orientable. The most familiar is the 3-Torus. Absent dark energy, a flat universe expands forever but at a continually decelerating rate, with expansion asymptotically approaching some fixed rate. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The The flatness problem is a cosmological fine-tuning problem within the Big Bang model; i.e., the observation that the current density of the universe is very close to its critical value at which space is perfectly flat. Since the total energy density of the universe departs rapidly from the critical value over cosmic time, the early universe must have had a density even closer to the critical density (see below), leading cosmologists to question how the density of the early universe came to be fine-tuned to this 'special' valueultimate fate of the universe is the same as that of an open universe.

Answer 3

The term flat refers to the the plane geometry of the universe. The possible shapes of the universe - closed, open, and flat are determined by the value of omega which is the value of the matter density of the universe. When omega =1 the matter density is said to be at critical value and the universe is considered flat. This means that the universe will continue expanding, but at an ever slowing rate that will forever approach but not quite reach stasis. Basically this means that the universe will expand forever, and will never collapse.

Answer 4

This is a very interesting question. According to Einstein, the Space is actually flat. The huge mass of the Sun cause the space around it to curve. Imagine holding all 4 corners of a piece of cloth. Put a round and heavy object in the centre...lets say a 1kg ball. You will notice that the cloth curves inwards. This is exactly what is going on in the universe...the cloth is space and the ball is Sun.

In fact, this curvature of space is the reason why planets orbit around the Sun. And if i continue to explain, it will lead to the fact that gravity is not a force. Gravity is geometry. I am not making this up. This is a fact and its proven by Einstein. The concept of Relativity is hard to understand. There is a quote by a famous physicist : 'If you are not confused about relativity, then you have not understand it at all'

Go and look up on Relativity, Einstein, Astronomy and Space. Its very interesting. Hard to believe but its true. Be careful though...some facts on the net are not true. Have fun exploring.

Answer 5

Actually, it probably isn't flat, and astronomers are working busily to find out whether ii is flat, hyperbolic, or ellipsoidal. The term refers to the curvature of space-time caused by the presence of matter, and does not refer to anything that is easily observable on earth.

Answer 6

We are in orbit around the sun. Now why all the planets are in the same orbit..which looks flat..Don't know. Check out www.hubbletelescope.com all universes are that way. My favorite is the Eagle nebula.