The Cosmic Triangle: Revealing the State of the Universe

TLDR

The cosmic triangle visualizes the universe’s past, present, and future. The study seeks to locate our position in the cosmic triangle by determining the universe’s matter density, expansion rate, and spatial curvature. Observations indicate a low‑density, accelerating, flat universe, implying the presence of dark energy that counteracts gravity.

Abstract

The cosmic triangle is introduced as a way of representing the past, present, and future status of the universe. Our current location within the cosmic triangle is determined by the answers to three questions: How much matter is in the universe? Is the expansion rate slowing down or speeding up? And, is the universe flat? A review of recent observations suggests a universe that is lightweight (matter density about one-third the critical value), is accelerating, and is flat. The acceleration implies the existence of cosmic dark energy that overcomes the gravitational self-attraction of matter and causes the expansion to speed up.