All the things in the universe that we can easily see — stars, nebulae, and so on — amount to less than 1% of all the matter and energy that's known to be out there.
"Dark matter" and "dark energy" account for 95.4% of everything, judging by many lines of converging evidence (see the June Sky & Telescope, page 14). But that still leaves 4.6% of everything as “ordinary” matter: material made of protons, neutrons, and electrons, the stuff of atoms. Until recent years, astronomers could only tally up about half as much ordinary matter as cosmologists said there ought to be, judging from the state of the universe soon after the Big Bang.
Now the mystery seems solved. In recent years astronomers had already found signs that the missing ordinary matter indeed exists, as a thin, elusive gas between galaxies known as the “warm-hot intergalactic medium,” or WHIM.
"Dark matter" and "dark energy" account for 95.4% of everything, judging by many lines of converging evidence (see the June Sky & Telescope, page 14). But that still leaves 4.6% of everything as “ordinary” matter: material made of protons, neutrons, and electrons, the stuff of atoms. Until recent years, astronomers could only tally up about half as much ordinary matter as cosmologists said there ought to be, judging from the state of the universe soon after the Big Bang.
Now the mystery seems solved. In recent years astronomers had already found signs that the missing ordinary matter indeed exists, as a thin, elusive gas between galaxies known as the “warm-hot intergalactic medium,” or WHIM.
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