Classical Music Little-Known Favorites

I’ve been seriously listening to classical music—both through live performance and recordings—for nearly 50 years, and am always surprised to find that I still discover or am introduced to works that are new to me and extraordinarily moving. “How can I have gone so many years without discovering this?” I often ask myself when I hear such a piece. Often, these “new” works are by well-known composers, but sometimes they are by composers I have never heard of. And, of course, some of them are new works by living composers.

For example, in 2017, I created a continuously-updated blog entry for “Symphonies by Women” because I was embarrassed to admit I couldn’t name a single one off the top of my head. Well, as you can see there are hundreds, and some of the few I have had the privilege to hear are really good.

There is an enormous amount of unknown music out there, and if only 1% of this unknown music is first-rate, then there must be hundreds of composers and thousands of works that deserve more attention. In France, Thanh-Tâm Le, who has recently helped me so much with this list of symphonies by women, has compiled a larger list of almost 18,000 symphonies by both men and women, and that is only symphonies!

Do you have some favorite classical works (both new and old) that you only know through a live performance or a non-commercial recording? Do you have some favorite works on vinyl or CD that are not currently available on CD? I know I do.

I’ve created a discussion group on groups.io called Classical Music Little-Known Favorites where I hope you and others will post audio files, YouTube videos, etc., of little-known works that you are enamored of. My hope for this group is that music lovers all around the world will join and present new and neglected works for us to enjoy and champion. Please join and spread the word!

The Early Radio Universe

As the expanding universe cooled, the first neutral1 hydrogen atoms formed about 380,000 years after the Big Bang (ABB), and most of the hydrogen in the universe remained neutral until the first stars began forming at least 65 million years ABB.

The period of time from 380,000 to 65 million years or so ABB is referred to as the “dark ages” since at the beginning of this period the cosmic background radiation from the Big Bang had redshifted from visible light to infrared so the universe was truly dark (in visible light) until the first stars began to form at the end of this period.

All the while, neutral hydrogen atoms occasionally undergo a “spin-flip” transition where the electron transitions from the higher-energy hyperfine level of the ground state to the lower-energy hyperfine level, and a microwave photon of wavelength 21.1061140542 cm and frequency 1420.4057517667 MHz is emitted.

Throughout the dark ages, the 21 cm emission line was being emitted by the abundant neutral hydrogen throughout the universe, but as the universe continued to expand the amount of cosmological redshift between the time of emission and the present day has been constantly changing. The longer ago the 21 cm emission occurred, the greater the redshift to longer wavelengths. We thus have a great way to map the universe during this entire epoch by looking at the “spectrum” of redshifts of this particular spectral line.

380,000 and 65 million years ABB correspond to a cosmological redshift (z) of 1,081 and 40, respectively. We can calculate what the observed wavelength and frequency of the 21 cm line would be for the beginning and end of the dark ages.

\lambda _{obs} = (z+1)\cdot \lambda_{emit}


The observed wavelength (λobs) for the 21 cm line (λemit) at redshift (z) of 1,081 using the above equation gives us 22,836.8 cm or 228.4 meters.

\nu = \frac{c}{\lambda }


That gives us a frequency (ν) of 1.3 MHz (using the equation above), where the speed of light c = 299,792,458 meters per second.

So a 21 cm line emitted 380,000 years ABB will be observed to have a wavelength of 228.4 m and a frequency of 1.3 MHz.

Using the same equations, we find that a 21 cm line emitted 65 Myr ABB will be observed to have a wavelength of 8.7 m and a frequency of 34.7 MHz.

We thus will be quite interested in taking a detailed look at radio waves in the entire frequency range 1.3 – 34.7 MHz, with corresponding wavelengths from 228.4 m down to 8.7 m.2

The interference from the Earth’s ionosphere and the ever-increasing cacophony of humanity’s radio transmissions makes observing these faint radio signals all but impossible from anywhere on or near the Earth. Radio astronomers and observational cosmologists are planning to locate radio telescopes on the far side of the Moon—both on the surface and in orbit above it—where the entire mass of the Moon will effectively block all terrestrial radio interference. There we will finally hear the radio whispers of matter before the first stars formed.

1 By “neutral” we mean hydrogen atoms where the electron has not been ionized and resides in the ground state—not an excited state.

2 Incidentally, the 2.7 K cosmic microwave background radiation which is the “afterglow” of the Big Bang itself at the beginning of the dark ages (380,000 years ABB), peaks at a frequency between 160 and 280 GHz and a wavelength around 1 – 2 mm. So this is a much higher frequency and shorter wavelength than the redshifted 21 cm emissions we are proposing to observe here.

References

Ananthaswamy, Anil, “The View from the Far Side of the Moon”, Scientific American, April 2021, pp. 60-63. https://www.scientificamerican.com/article/telescopes-on-far-side-of-the-moon-could-illuminate-the-cosmic-dark-ages1/

Burns, Jack O., et al., “Global 21-cm Cosmology from the Farside of the Moon”, https://arxiv.org/ftp/arxiv/papers/2103/2103.05085.pdf

Koopmans, Léon, et al., “Peering into the Dark (Ages) with Low-Frequency Space Interferometers”, https://arxiv.org/ftp/arxiv/papers/1908/1908.04296.pdf

Ned Wright’s Javascript Cosmology Calculator, http://www.astro.ucla.edu/~wright/CosmoCalc.html