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What Your Grandma’s TV Can Tell Us About the Ancient Universe

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Zoe Reed

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If you’ve ever used an analog television, you’re likely not surprised to hear that the static “snow” you experience when flicking through channels is a result of different electromagnetic waves interfering with the TVs signal. You may, however, be surprised that a portion of those waves, particularly in the microwave spectrum, can be traced all the way back to 13.8 billion years ago in the form of the Cosmic Microwave Background (CMB) (Jones and Lasenby 1998). 

The CMB is the oldest detectable light in the universe, dated around 380,000 years after the Big Bang (Jones and Lasenby 1998). At this point in cosmic history, the universe was so hot and high energy that it was composed entirely of a thick, opaque mass of continually ionized protons, electrons, and photons, rather than the collection of planetary masses we see today (Jones and Lasenby 1998). Light was trapped in this thick mass, and could not travel freely as photons continually scattered off free electrons (Mather et al. 2013). The universe gradually expanded such that this energy could disperse, and once it had cooled to approximately 3000 K, protons and electrons bound together to form hydrogen atoms in what is called the primordial nucleosynthesis (Mather et al. 2013). With electrons now locked into atoms, photons stopped constantly scattering off free electrons, and light was suddenly released to travel across space unhindered (Mather et al. 2013; Jones and Lasenby 1998). 

When these photons were first released, they possessed high thermal energy with wavelengths in the visible and near-infrared spectrum. However, as the universe continued to expand over the next 13.8 billion years, it stretched the wavelength of the light traveling through it – a phenomenon known as cosmological redshift, for how this light becomes red as its wavelength increases (Zhang 2025). Over 13.8 billion years, this process increased the wavelength of the primordial photons by a factor of roughly 1,100, shifting them out of the visible light spectrum and into the low-energy microwave spectrum (Aghanim et al. 2020). Today, this radiation permeates uniformly at a temperature of 2.7255 K, or -270.4245 °C, with this low energy placing it firmly in the thermal blackbody spectrum (Mather et al. 2013). 

Regardless of its low energy, this radiation can be picked up by an analog TV antenna and cause a very small amount of interference in the television signal. So next time you’re using an old TV, know that some signals you pick up might be as ancient as the atom.

References

Aghanim, N., Y. Akrami, M. Ashdown, J. Aumont, C. Baccigalupi, M. Ballardini, A. J. Banday, et al. 2020. “Planck 2018 Results: VI. Cosmological Parameters.” Astronomy & Astrophysics 641: A6. https://doi.org/10.1051/0004-6361/201833910.

Jones, A. W., and A. N. Lasenby (Living Reviews in Relativity). 1998. “The Cosmic Microwave Background.” Switzerland. PubMed Central. https://doi.org/10.12942/lrr-1998-11. 

Mather, John, Gary Hinshaw, and Lyman Page. 2013. “Cosmic Microwave Background”Planets, Stars and Stellar Systems (Dordrecht), 609–84. https://doi.org/10.1007/978-94-007-5609-0_13. 

‌Zhang, Wenzhong David. 2025. “Quantitative Derivation of the Cosmic Microwave Background Radiation Spectrum and Temperature and Its Relationship with the Hubble Constant”AIP Advances 15(7). https://doi.org/10.1063/5.0266308. 

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Comments

3 Responses to “What Your Grandma’s TV Can Tell Us About the Ancient Universe”

  1. Kristen Taylor Avatar
    Kristen Taylor

    Hi Zoe,

    Fascinating topic choice and great job on your blog post! Here are a few suggestions I had for your edits:
    – In sentence 2 of paragraph 2, I believe “high energy” should be hyphenated (“high-energy”).
    – In sentence 3 of paragraph 2, I recommend adding a comma after the word “freely”.
    – Consider adding a figure to support your text!
    – Don’t forget to add a comment to explain why you chose your topic.

    Overall, great work and good luck with your edits!
    Kristen

  2. Zoe Reed Avatar
    Zoe Reed

    Hi iSci!

    I chose this topic as in Neuro we’re looking at the brain as a circuit and the different electromagnetic signals within it, and it got me thinking about this fact that I half-remembered that some of old TV static is leftover from the big bang. I thought the electromagnetism of it all connected well, so I wrote a blog post on it!

  3. Kurtis Ng Avatar
    Kurtis Ng

    Hi Zoe!

    This was such a cool read, I love how you took something as everyday as TV static and connected it all the way back to the early universe. Here are some suggestions for improvements:

    – P2S5: Hydrogen atoms forming once the universe cooled to ~3000 K is called “recombination,” not “primordial nucleosynthesis.” Nucleosynthesis happened only a few minutes after the Big Bang and formed the first nuclei, so it may be worth swapping the term.

    – P3S2: “for how this light becomes red as its wavelength increases” reads a bit awkwardly; maybe “named because the light shifts toward the red end of the spectrum as its wavelength increases.”

    – P4S1: “a very small amount of interference” could be made more concrete. A commonly cited estimate is that roughly 1% of analog TV static comes from the CMB, which would be a great hook to end on (with a citation).

    – Bigger picture: P3S4 says the radiation “permeates uniformly,” but one of the coolest parts of the CMB is its tiny temperature fluctuations (about 1 part in 100,000) mapped by Planck, which seeded galaxies. A sentence on this would tie in nicely with your Aghanim et al. (2020) reference!

    I learned a lot about where TV static actually comes from. Can’t wait to see the final copy!

    – Kurtis

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