The ocean holds more viruses than the sky holds stars
A standard estimate puts on the order of 10 to the 30 virus particles in the oceans. The observable universe holds on the order of 10 to the 22 or 10 to the 24 stars.
Strong2 min read
A millilitre of surface seawater contains on the order of ten million viruses, most of them phages infecting bacteria. Multiply by the volume of the ocean and the census lands near 10^30. Curtis Suttle's review in Nature made that number the working estimate.
Stars are fewer even if you are generous. A hundred billion galaxies of a hundred billion stars is 10^22. Stretch the assumptions and you may reach 10^24. You do not reach 10^30. The gap is many orders of magnitude wide, which is why the sloppiness of both censuses does not threaten the comparison.
Caveats
- These are virus particles, overwhelmingly infecting microbes. They are not a reservoir of human diseases.
- Both sides are estimates. The inequality is the claim, not any one significant figure.
Sources
- 1Suttle C. A.. Viruses in the sea. Nature 437, 2005.