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Missing Matter found?

Has the Big Bang’s missing matter been found?

Artist’s impression of a fast radio burst traveling through space and reaching Earth
Published: 1 May 2021 (GMT+10)

Jacob R, asks for a response to a recent study claiming to have found the ‘missing’ baryonic matter. Baryons are the heavy normal matter particles that include protons and neutrons. Baryons make up us, the food we eat, the earth, planets, moons, stars, black holes, intergalactic gas etc. 

The Big bang model predicts1 that the universe is made up of 71% dark energy, 24% dark matter and 5% baryonic matter. Curiously, less than half of the expected baryonic matter is actually observed.

It is this ‘missing’ baryonic matter that the recent study is claiming to have found. The search for dark matter and dark energy are separate issues.

Jacob R. from Australia wrote:

‘As of a few days ago there was a video posted about scientists ‘finding’ the (predicted) hidden baryonic matter of the universe (using the big bang to make this prediction). I usually take these claims very skeptically and like to wait until a response from CMI is made. The study cited by this video is fairly recent (May 2020) and I am unable to find a response on your website (I know you do not allow rebuttals of websites, I figured since I am citing a claim that you would appreciate a source). If you could give a creationist explanation/or point me in the direction of one I would greatly appreciate it.’

Scot Devlin, CMI, responds:

Good question. I am not aware of a creationist response to this particular study. It will be interesting to see if there is a secular response as using the dispersion of fast radio bursts (FRBs) to estimate baryonic matter is a very new technique. FRBs were discovered in 2007 and an accurate way of locating their source only came in 2019.2 Therefore, this study is hot off the press and uses only 5 good data points. There will likely be a bigger variety of detected (and located) FRBs in the near future.3 It will be interesting to see if the forthcoming data agree on the cosmic baryon density as calculated by this study.

Also note that this is not the first claim to the finding of the missing baryons!4 One study in 20185 and two studies in 20176,7 have claimed to have solved the missing baryon problem. We commented on an earlier ‘find’, in 2011.

The 2018 study detects ionised oxygen (and therefore calculates the interstellar hydrogen by inference) by identifying oxygen isotope absorption lines in distant quasar spectra. The 2017 studies both identify an increase in temperature at the assumed cosmic web filament locations (compared to the rest of intergalactic space). This is proposed to be a result of inverse-Compton scattering of CMB photons off the free electrons in the cosmic web filaments, otherwise known as the thermal Sunyaev—Zeldovich effect: The CMB photons gain energy as they are scattered off the free electrons. This is a small effect, and for it to be identifiable, the studies had to add together the signals from many different cosmic web filament sections (260,000 and 1 million respectively). They were then able to calculate the number of free electrons and therefore (assuming overall neutrality of the plasma) the number of baryons in intergalactic filaments.

In comparison, the 2020 study uses the dispersion measure of FRBs to calculate all baryonic matter. This seems like a better technique, as the signal is not from such a faint source, so stacking hundreds of thousands of separate signals is not required. But as I mentioned, it is a new technique, so let’s wait to see some more measurements, as well as potential rebuttals to the technique’s accuracy.

In conclusion, the reasons to be cautious about this missing baryon ‘find’ are:

  1. Multiple earlier claims show that each earlier claim did not find the missing matter. Otherwise, why keep searching!
  2. From a biblical perspective, we will not be surprised if it turns out that the relative abundance of baryons in the universe is more or less than 5% because this figure is calculated using the Big Bang model along with its naturalistic assumptions.
  3. The small number of data points used.

If more FRB’s can better establish this result, and other novel methods agree, it could then be asked, have we found 5% because 5% is what was expected? I.e., If the target were 9% would a continued search reveal an additional 4%?

Keep in mind that the bigger baryon problem for the big bang is the missing anti-baryons or the ‘baryon asymmetry problem’: an equal number of anti-electrons should have formed with the condensation of normal matter particles near the beginning of the Big Bang. However, they are not observed!

Jacob R, continues:

If you have any general advice on how to navigate secular cosmology it would be greatly appreciated.

Good question, it is an ever expanding and diverging field (excuse the pun). All of our articles relating to Cosmology can be found on the Q&A page.

If you would like to start with a book, try ‘Dismantling the Big Bang’ by Williams and Hartnett.

Kind regards
Scot Devlin

References and notes

  1. In the late 1990s, a team of cosmologists used the observed ratios of the light elements in the universe (hydrogen, helium, deuterium) with the Big bang model to make this prediction. A study in 2001 used temp fluctuations in the CMB (Cosmic Microwave Background radiation) along with the big bang model to predict a similar relative abundance of baryons. Return to text.
  2. Prochaska, J.X. et al., Probing Galactic Halos with Fast Radio Bursts, arxiv.org, 1 Feb 2019. Return to text.
  3. There are currently only 40 known sources of FRBs (ie. 40 points in the sky) But a new telescope is listening for more: It is hoped that the CHIME telescope in Canada will be able to listen to a dozen a day: https://globalnews.ca/news/4370531/chime-frb-outside-our-galaxy/. Return to text.
  4. Half of the universe’s missing matter has just been finally found, newscientist.com, accessed 29 Apr 2021. Return to text.
  5. Nicastro, F., Kaastra, J., Krongold, Y. et al. Observations of the missing baryons in the warm–hot intergalactic medium. Nature 558, 406–409, 2018. Return to text.
  6. Tanimura, H. et al., A search for warm/hot gas filaments between pairs of SDSS Luminous Red Galaxies, Monthly Notices of the Royal Astronomical Society 483(1):223–234, Feb 2019. Return to text.
  7. De Graaff, A. et al., Missing baryons in the cosmic web revealed by the Sunyaev-Zel’dovich effect, arxiv.org, 29 Sep 2017. Return to text.

Helpful Resources

Dismantling the Big Bang
by Alex Williams, John Hartnett
US $17.00
Soft Cover