Thus, dark matter constitutes 85% of the total mass, while dark energy and dark matter constitute 95% of the total mass-energy content. In the standard Lambda-CDM model of cosmology, the total mass-energy content of the universe contains 5% ordinary matter and energy, 27% dark matter, and 68% of a form of energy known as dark energy. Other lines of evidence include observations in gravitational lensing and the cosmic microwave background, along with astronomical observations of the observable universe's current structure, the formation and evolution of galaxies, mass location during galactic collisions, and the motion of galaxies within galaxy clusters. Some galaxies would not have formed at all and others would not move as they currently do. The primary evidence for dark matter comes from calculations showing that many galaxies would behave quite differently if they did not contain a large amount of unseen matter. For this reason, most experts think that dark matter is abundant in the universe and has had a strong influence on its structure and evolution. Various astrophysical observations – including gravitational effects which cannot be explained by currently accepted theories of gravity unless more matter is present than can be seen – imply dark matter's presence. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation (like light) and is, therefore, difficult to detect. Read the original article here.Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. This article was originally published on Universe Today by Brian Koberlein. And it’s good to know that if your evil doppelganger is out there, they can only influence your life gravitationally. A more detailed model will be needed for that. It lays out how this cosmic invariance might solve the Hubble constant problem but doesn’t go so far as to prove it’s a solution. It should be pointed out that this study is mostly a proof of concept. One that would affect our universe through a faint gravitational pull. If you impose this symmetry more broadly, you can scale the rate of gravitational free-fall and the photon-electron scattering rate so that the different methods of Hubble measurement better agree.Īnd if this invariance is real, it implies the existence of a mirror universe. The team found that when you tweak cosmological models to match the observed expansion rates, several unitless parameters stay the same, which suggests an underlying cosmic symmetry. Basically, you can combine measured parameters in such a way that all the units cancel out, giving you the same number no matter what units you use, which is great if you are a theoretician. The most famous of these is the fine structure constant, which has a value of about 1/137. How they did it - The team discovered an invariance in what are known as unitless parameters. Our universe may have its own antimatter twin that exerts a gravitational pull on our own. Measurements of fluctuations in the cosmic microwave background point toward a lower value, around 67 km/sec/Mpc, while observations of objects such as distant supernovae yield a higher value, around 73 km/sec/Mpc. This is sometimes known as the cosmic tension problem.Īt this point, the observed values of the Hubble constant cluster into two groups. In fact, in the past several years, measurements have become so precise they outright disagree. (Give or take quite a bit.)Īstronomers figured that as our measurements became precise, the various methods would settle on a common value, but that didn't happen. Over the next several decades, measurements of this expansion settled on a rate of about 70 kilometers/second/Mpc. This expansion was first demonstrated by Edwin Hubble, using data from Henrietta Leavitt, Vesto Slipher, and others. Here’s the background - The Hubble constant, or Hubble parameter, is a measure of the rate at which our universe expands. A world is similar to ours where we might find our evil doppelganger or a version of us who actually asked out our high school crush.īut the concept of a mirror universe has often been studied in theoretical cosmology, and as a new study shows, it might help us solve problems with the cosmological constant. The idea of a mirror universe is a common trope in science fiction.
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