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Dark Matter and Dark Energy

What is the universe made of?​

The diagram below shows data from several sources that rule out long-held ideas about how much matter and energy the universe contains and what kinds. These data tell us that the total matter-energy content of the universe must include the invisible dark matter that holds it together, and the mysterious dark energy that pushes it apart. The vertical axis shows the amount of dark energy. The horizontal axis shows the amount of matter, both visible and dark. insert image description here What is it made of? The pink dots show the total matter and energy needed to be consistent with all modern cosmological data. Observations from many sources rule out a universe made up of just ordinary matter. They need dark matter and a lot of dark energy to fill the 'matter-energy gap' and reach a total amount of matter and energy consistent with the data.

CMB Cosmic Microwave Background​

The Cosmic Microwave Background (CMB) is the light emitted from the hot plasma of the Big Bang nearly 14 billion years ago, an 'echo' of the Big Bang. To reach us, images of this ancient universe had to travel for billions of years as it expanded. measurable patterns in the CMB tell us what the matter and energy content of the universe was like when the light was emitted, and how it has changed over time. Models of the matter and energy of the Universe beyond the green concentric ellipses do not match the CMB data.

Clusters of Galaxies​

Clusters of galaxies are the most massive objects in the Universe. In addition to galaxies, these systems contain large amounts of hot gas, which emit X-rays. The temperature of the X-ray emitting gas and the speed at which it orbits the galaxy allow us to deduce the total mass of a galaxy cluster, which is much greater than the mass of the galaxy or the hot gas. This extra mass is in the form of dark matter; measurements of clusters tell us the total amount of dark matter in the Universe. As a function of cosmic time, the abundance of clusters also gives us information about how much dark energy is present. The matter and energy models outside the orange ellipse do not explain the properties of the observed clusters.

Supernovae Supernovae​

Supernovae, explosive stars that shine briefly like galaxies, can be observed at such great distances that they can be used to measure the evolution of the universe. There is one type of supernova that always seems to emit the same amount of light at its peak brightness. By measuring the brightness of one of these supernovae, we can tell how far away it is. Comparing this distance with the observed speed of the supernova tells us how the Universe has expanded over cosmic time. Mass and energy models beyond the blue ellipse predict an evolution of the Universe that is inconsistent with observations of supernovae.

Standard Model Matter Standard Model Matter​

Laboratory experiments have determined the behaviour of known matter particles. With this knowledge, we can determine how particle interactions affect important processes in the universe. The amount of light elements such as deuterium, helium and lithium made in the Big Bang, as well as the propagation of sound waves in the early universe, can be observed in the CMB in patterns that precisely determine the total amount of 'standard model matter' contained in the universe. The dark blue dots indicate the contribution of this matter to the total matter and energy of the universe.