Is the universe flat?
This isn’t flat as in two dimensional, rather it is flat as in the two forces, attractive by gravity and repulsive by dark energy, are equal to one another. This had huge impact on the outcome of the universe. Scientists have mapped the night sky to determine how much matter there is in the universe and calculated it all up to determine the overall gravitational force. Next they calculated the force of expansion in the universe as it counteracts against gravity.
If gravity it stronger than the repulsive force than the universe is closing in on itself and will one day, theoretically, all the matter will collapse in it itself. Some believe this may cause the universe to spring back out in another “Big Bang”. If the repulsive force is stronger than gravity than the universe will expand infinitely. The universe will expand; the last stars will fizzle out and continue to be a cold lifeless place. However the scientists found that the universe is flat, the force of gravity is equal to the repulsive force, in this universe everything is more stable and the outcome of the universe is less apparent.