US Withdrawal of Support for CMB-S4 Telescope is Catastrophic

In the words of Robert Frost from The Road Not Taken, “Two roads diverged in a yellow wood / And sorry I could not travel both.”

This sentiment resonates as I reflect on the U.S. government’s July 9 announcement: CMB-S4 projects will no longer receive support. CMB-S4 (Cosmic Microwave Background Stage 4) was set to be the next groundbreaking multicontinental telescope system, promising unparalleled insights into the oldest light traversing the universe.

Initially, the universe was a turbulent mix of dense particles and plasma, so thick that photons (light particles) could scarcely move without colliding with something. This primordial environment was also extremely hot, hindering the formation of atoms. It wasn’t until cosmic inflation—a rapid expansion of spacetime lasting an imperceptibly short period—that temperatures fell sufficiently to allow the first hydrogen atoms to form, providing photons the freedom to zip across space.

Sixty-one years ago, we discovered the existence of these photons, known as cosmic microwave background radiation (CMB). What began as mere background noise in radio signals has been recognized as a link to the early universe, leading us to meticulously analyze the wavelengths, intensities, and variations of these photons.

The CMB offers a trove of information regarding the origins of all matter we observe, including stars that later create gold through supernovae. By surveying the entire sky for changes in photon temperatures, we can identify minute fluctuations in temperature. While their positions appear random, the magnitude of these variations is consistent across the board.

Our prevailing theory posits that these fluctuations arise from tiny quantum variations in matter density at the time the photons were released. Greater concentrations of matter served as the seeds for gas accumulation, which ultimately merged into protostars, leading to the formation of stars and galaxies. Thus, these CMB fluctuations mark our cosmic genesis.

One of the most significant measurements we’ve derived from the CMB is how its temperature fluctuations correlate with various physical scales. Understanding the distances over which particular phenomena manifest allows us to analyze the variation’s origins—whether from larger or smaller scales. Essentially, different epochs in cosmological history are imprinted within the CMB.

For instance, we can “detect” when the universe became transparent to matter and when hydrogen first formed, an epoch referred to as recombination. Although these events are beyond our visual perception, we can gauge the presence of dark matter and dark energy based on their influence on the CMB.

CMB-S4 aimed to advance our understanding of the lessons the CMB has to offer. An important objective was to seek evidence of primordial gravitational waves, ripples in spacetime associated with cosmic inflation. Although different inflationary models propose plausible physical descriptions of our universe, specific details remain elusive. The signatures of gravitational waves on the CMB may provide the most effective means of distinguishing among these models.

The cessation of government backing for CMB-S4 is akin to jamming a bike’s wheel, abruptly halting our exploration of the cosmos. The repercussions will be felt globally. Historically, the U.S. has made significant investments in cosmological science, which attracts students internationally to its educational institutions. U.S.-sourced experimental data typically serves as a critical global resource. The retreat from the project, which seemed likely under the former administration, is now part of a broader trend of the U.S. distancing itself from global collaboration.

Frost concludes his poem by reflecting on the implications of his chosen path. It is indeed regrettable that the United States has opted not to explore the less traveled road in scientific pursuits. It undoubtedly makes an impact, but unfortunately, not for the better.

A week in Chanda

What I am reading

I find the works of Niaesh Afsholdi and Phil Halper captivating. Their book, The Battle of the Big Bang: A New Story About the Origins of Our Universe, is particularly intriguing.

What I see

I keep rewatching DC Universe movies, especially those featuring my favorite character, Harley Quinn.

What I am working on

I’ve been attempting to capture stunning images of the Andromeda Galaxy from my backyard.