type of matter or energy |
W, amount (relative to that needed for flat geometry) |
how we know the amount |
what it is (or might be) |
evidence for what it is |
where it is |
Cosmic Microwave Background photons (CMB) |
0.0001 |
direct measurement |
photons left over from the Big Bang (there are 109 photons for every baryon) |
discovered by Penzias & Wilson (Nobel Prize 1978) COBE WMAP (Nobel Prize 2006) |
everywhere |
baryonic bright matter (stars, planets, people...) the insignificant portion of the universe studied by chemists & biologists |
0.005 |
see it; count it by assigning a mass to a given luminosity |
mostly stars, but also interstellar medium, planets, etc. |
we see the light it emits |
concentrated in the disks of spiral galaxies; |
baryonic dark matter (baryonic = neutrons & protons or matter like us) |
.044 (+ 0.004) |
Big
Bang production of the light elements: |
1) MACHOs
2) hot
gas between galaxies |
1) gravitational microlensing 2) absorption in the spectra of distant quasars (May 2000) x-ray emission from clusters of galaxies |
1) haloes of galaxies
2) within/betwen clusters of galaxies |
non-baryonic dark matter |
0.23 (+ .02) |
a) rotation curves of spiral galaxies: Vrot remains constant up to the visible edge of a galaxy b) gravitational macrolensing (1995 - ) gravitational lens picture gallery dark matter ring discovered in early 2007 Hubble animation c) degree of large-scale clustering of galaxies (2000 - ) d) separation of light and dark matter during galactic collisions (2006 - 2008) (1) bullet cluster from APOD 8/24/06 bullet-cluster animation/video from Chandra 2006... original article (2) MACS cluster clash found by Chandra in mid-2008 |
particles with existence evidence: 1) neutrinos particles without existence evidence: 2) axions ?? 3) neutralinos?? the Search for Dark
Matter
Universe
Reveals |
1) at least some neutrinos (2?) have mass, but we can only measure mass differences between neutrino species (Nobel Prize 2002) 2) discovered -- or maybe not ? (Feb 2000) |
haloes of galaxies |
dark energy |
0.73 (+ .04) |
1) distant supernovae are fainter than expected 2) flat geometry of the universe requires something else besides matter |
1) Einstein's cosmological constant ?? 2) quantum vacuum energy?? 4) novel behavior of matter?? |
none |
everywhere |
(total) |
(+ .02) |
in the CBR |