Understanding the how our universe came to be what it is today and what will be its final destiny is one of the biggest challenges in science. The awe-inspiring display of countless stars on a clear night gives us some idea of the magnitude of the problem, and yet that is only part of the story. The deeper riddle lies in what we cannot see, at least not directly: dark matter and dark energy. With dark matter pulling the universe together and dark energy causing it to expand faster, cosmologists need to know exactly how much of those two is out there in order to refine their models.
At ETH Zurich, scientists from the Department of Physics and the Department of Computer Science have now joined forces to improve on standard methods for estimating the dark matter content of the universe through artificial intelligence. They used cutting-edge machine learning algorithms for cosmological data analysis that have a lot in common with those used for facial recognition by Facebook and other social media.
Their results have recently been published in the scientific journal Physical Review D. While there are no faces to be recognized in pictures taken of the night sky, cosmologists still look for something rather similar, as Tomasz Kacprzak, a researcher in the group of Alexandre Refregier at the Institute of Particle Physics and Astrophysics, explains: "Facebook uses its algorithms to find eyes, mouths or ears in images; we use ours to look for the tell-tale signs of dark matter and dark energy.
This effect, known as "weak gravitational lensing," distorts the images of those galaxies very subtly, much like far-away objects appear blurred on a hot day as light passes through layers of air at different temperatures. Cosmologists can use that distortion to work backwards and create mass maps of the sky showing where dark matter is located. Next, they compare those dark matter maps to theoretical predictions in order to find which cosmological model most closely matches the data. Traditionally, this is done using human-designed statistics such as so-called correlation functions that describe how different parts of the maps are related to each other.
Such statistics, however, are limited as to how well they can find complex patterns in the matter maps. Main article: Dark matter in fiction. See Baryonic dark matter.
It is basically the same except that dark energy might depend on scale factor in some unknown way rather than necessarily being constant. Strictly speaking, electrons are leptons not baryons ; but since their number is equal to the protons while their mass is far smaller, electrons give a negligible contribution to the average density of baryonic matter. Baryonic matter excludes other known particles such as photons and neutrinos. Hypothetical primordial black holes are also generally defined as non-baryonic, since they would have formed from radiation, not matter.
CERN Physics. The Dallas Morning News.
Annual Review of Astronomy and Astrophysics. Planck Collaboration 22 March Astronomy and Astrophysics. Ars Technica.
University of Cambridge. Retrieved 21 March Dark Matter, Dark Energy: The dark side of the universe. The Teaching Company. Hidden cosmos.
This means we can only see some of the galaxies in the Universe, which is the main reason why the night sky is dark. Just how dark can be calculated using the . Buy Dark Sky, Dark Matter (Series in Astronomy and Astrophysics) on Amazon. com ✓ FREE SHIPPING on qualified orders.
National Geographic Magazine. Retrieved 10 June Astrophysical Journal Supplement. Bibcode : ApJS.. Bibcode : Sci Physics Reports. Bibcode : PhR Monthly Notices of the Royal Astronomical Society. Nature Astronomy. Bibcode : NatAs Retrieved 8 February Astrophysical Journal.
Bibcode : ApJ It is incidentally suggested when the theory is perfected it may be possible to determine the amount of dark matter from its gravitational effect. Bulletin of the Astronomical Institutes of the Netherlands. Bibcode : BAN Imagine the Universe! July Helvetica Physica Acta. Bibcode : AcHPh The Astrophysical Journal. The cosmic cocktail: Three parts dark matter. Princeton University Press.
www.cantinesanpancrazio.it/components/zapajez/223-trovare-la.php Lick Observatory Bulletins. Bibcode : LicOB.. April June The New York Times. Retrieved 27 December Archived from the original on 25 June Retrieved 6 August Kent, Jr. February The distribution and kinematics of neutral hydrogen in spiral galaxies of various morphological types PhD Thesis. Rijksuniversiteit Groningen.
May October Seth September Reports on Progress in Physics. Bibcode : RPPh Mathematical Tripos. Cambridge University. Archived from the original PDF on 2 February Retrieved 24 January European Southern Observatory. Galactic Astronomy. Retrieved 8 December Physics for the 21st Century. Annenberg Foundation.
The Register. For an intermediate-level introduction, see Hu, Wayne The Astrophysical Journal Supplement. Cosmological parameters".
Bibcode : PhRvL.. Modern Physics Letters A. Bibcode : MPLA The Astrophysical Journal Letters. Beijing, China.
Retrieved 16 March European Space Agency. Retrieved 9 February Bibcode : Natur. Physical Review Letters. Bibcode : PhRvL. Physics of the Dark Universe. Bibcode : PDU Swinburne University of Technology. Retrieved 9 April Big bang nucleosynthesis: Cooking up the first light elements.
Einstein Online. Archived from the original on 6 February An Introduction to the Science of Cosmology. IOP Publishing. The First Stars. ESO Astrophysics Symposia. Bibcode : fist. New J. Bibcode : NJPh November One widely held belief about dark matter is it cannot cool off by radiating energy. If it could, then it might bunch together and create compact objects in the same way baryonic matter forms planets, stars, and galaxies.
Observations so far suggest dark matter doesn't do that — it resides only in diffuse halos As a result, it is extremely unlikely there are very dense objects like stars made out of entirely or even mostly dark matter. Retrieved 7 January Retrieved 10 January The Big Bang: Third Edition.
In the pre-processing stage, we ran a python van Rossum and Drake, script to parse the raw particle and halo catalog datasets, using yt Turk et al. All-sky map of dark matter distribution in the Universe. In fact, there are very few stars in the halo of a galaxy and so Rubin measured the rotation rate here by tracking the motion of glowing clouds of hydrogen gas. The Structure of cold dark matter halos - Navarro, Julio F. Qualitative research methods in program evaluation. Bibcode : APh A Frozen flow approximation to the evolution of large scale structures in the universe - Matarrese, Sabino et al.
Henry Holt and Company. Silk Astrophysical Journal Letters.
Physics Letters B. Bibcode : PhLB.. Physical Review D. Bibcode : PhRvD.. Advances in Astronomy. Bibcode : AdAstE MACHOs can only account for a very small percentage of the nonluminous mass in our galaxy, revealing that most dark matter cannot be strongly concentrated or exist in the form of baryonic astrophysical objects.
Although microlensing surveys rule out baryonic objects like brown dwarfs, black holes, and neutron stars in our galactic halo, can other forms of baryonic matter make up the bulk of dark matter? The answer, surprisingly, is 'no' Retrieved 6 January Annual Review of Nuclear and Particle Science.
Retrieved 26 December Griest, Kim. Bibcode : EPJC Physics — Synopses. American Physical Society. Dark Matter Research. Sheffield: University of Sheffield. Kavli News. Sheffield: Kavli Foundation. Scientists at Kavli MIT are working on Space Telescope Science Institute.