Space.com posted an article on June 15, 2017, which is a good summary of this topic — “What is dark matter?”
Roughly 80 percent of the mass of the universe is made up of material that scientists cannot directly observe. Known as dark matter, this bizarre ingredient does not emit light or energy. So why do scientists think it dominates?
Most scientists think that dark matter is composed of non-baryonic matter.
If scientists can’t see dark matter, how do they know it exists?
The article summarizes some experiments trying to detect this stuff.
Another useful source for background on this topic is Dan Hooper’s book.
Hooper, Dan (2009-01-09). Dark Cosmos:In Search of Our Universe’s Missing Mass and Energy. HarperCollins. Kindle Edition. [Copyright 2006, prior to the LHC going online and Planck satellite]
Dark matter is a hypothetical type of matter distinct from baryonic matter (ordinary matter such as protons and neutrons), neutrinos and dark energy. The existence of dark matter would explain a number of otherwise puzzling astronomical observations. The name refers to the fact that it does not emit or interact with electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum. Although dark matter has not been directly observed, its existence and properties are inferred from its gravitational effects such as the motions of visible matter,gravitational lensing, its influence on the universe’s large-scale structure, on galaxies, and its effects in the cosmic microwave background.
The apparent expansion of the universe boggles the mind:
… studies of distant supernovae revealed that the universe today is expanding faster than it was in the past, not slower, indicating that the expansion is accelerating.
8 thoughts on “Hidden in plain sight — dark matter”
Space.com followed their June 15 article with another one on July 17, 2017, featuring an “Expert Voice” summary of the topic by Don Lincoln (Senior Scientist, Fermi National Accelerator Laboratory; Adjunct Professor of Physics, University of Notre Dame): Is Dark Matter Real?
Space.com published another article on Dark Matter today (August 14, 2017), again featuring an “Expert Voice” summary by Don Lincoln (Senior Scientist, Fermi National Accelerator Laboratory; Adjunct Professor of Physics, University of Notre Dame): Is Dark Matter Less ‘Lumpy’ Than Predicted?
Space.com published another article on Dark Matter today (August 25, 2017), this time featuring Paul Sutter, host of Ask a Spaceman, We Don’t Planet and COSI Science Now. The article is titled “The Matter with Dark Matter” and discusses the major evidence for its existence: too hot, too fast, too bumpy, too wide.
Space.com published another article on Dark Matter yesterday (November 2, 2017), this time featuring Adam Hadhazy, writer and editor for The Kavli Foundation, as part of Space.com’s Expert Voices: Op-Ed & Insights. The article is titled “New Map of Dark Matter Puts the Big Bang Theory on Trial” discusses a new cosmic map unveiled in August, plotting where the mysterious substance called dark matter is clumped across the universe.
Space.com today posted another article on dark matter “The Worst Theoretical Prediction in the History of Physics,” echoing the sentiment of the prior comment on this post.
Cosmological constant is … Holy zero-point energies and quantum foam, Batman!
A useful recap of dark matter research … early evidence … WIMPs … axions … sterile neutrinos … primordial black holes … hidden/dark-sector (with dynamics independent of normal matter vs. interacting with normal matter through the known weak force) … SuperCDMS (Super Cryogenic Dark Matter Search) experiment … mass range … tabletop experiments … computer simulations …
• Caltech Magazine > “Where is Dark Matter Hiding?” (Fall 2020) – Scientists turn to new ideas and experiments in the search for dark matter particles.
This article (below) is a useful reminder about the origin of “dark matter” models. And why that term (rather than “invisible matter” or “undetectable matter” or “missing mass”) has become so exotic. And ongoing research to detect it (directly or indirectly).
• APS Physics > “Dark Matter Alternative Passes Big Test” (October 15, 2021) – A cosmological model that doesn’t require dark matter has overcome a major hurdle in matching observations from the cosmic microwave background.
This research was briefly reported also by Phys.org.
• Phys.org > “New MOND theory able to account for cosmic microwave background” by Bob Yirka (October 21, 2021)
• Cf. Sloan Digital Sky Survey
See the reference to Mach’s principle in Wiki’s article for frame dragging (regarding relativistic effects in the vicinity of rotating black holes).
Making sense of all the data: Another galaxy cluster poses the question of invisible, undetectable matter – the missing mass called ‘dark’ matter.
• Space.com > “Hubble telescope spies a cosmic ‘spider web’ containing clues to dark secret” by Andrew Jones (October 31, 2022) – a huge cluster of galaxies exhibiting gravitational lensing hangs together despite an apparent mass shortfall.
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