Is the universe flat?

As of 2014, the universe is believed to be flat, according to the inflationary theory. This theory has to do with the density of the universe and suggests that the universe must be flat as piece of paper.

The WMAP spacecraft is the most advanced piece of modern technology for measuring the size and age of the universe. Using this equipment to measure the residual microwave radiation left over from the beginning of the universe, scientists have decided that the universe is flat with only a 0.4% possibility of error. Based on this conclusion, the universe could continue to expand forever, as long as the proper balanced is maintained between a flat universe and gravity.