Astronomers in the Distant Future Could Still Infer the Big Bang

In the distant future, approximately one trillion years from now, an extraterrestrial astronomer within our galaxy will face a formidable challenge in unraveling the origins of the universe. Unlike us, they will lack the wealth of evidence that we currently possess.

The groundbreaking work of Edwin Hubble provided the initial support for the Big Bang theory. Through his observations, Hubble demonstrated that galaxies are rapidly moving away from one another due to the expansion of the universe. More recently, astronomers have discovered the cosmic microwave background, a pervasive afterglow from the Big Bang that remains from the universe’s intensely hot inception.

However, in a trillion years, when the universe has aged a hundredfold, alien astronomers will perceive a vastly different reality. The Milky Way and the Andromeda galaxy will have merged, giving rise to the Milkomeda galaxy. Many stars, including our own Sun, will have exhausted their fuel and ceased to shine. The relentless expansion of the universe will propel all other galaxies beyond our “cosmic horizon,” forever vanishing from our view.

This expansion will also cause the cosmic microwave background to gradually diminish, stretching the wavelengths of its photons until they exceed the visible universe. Without the telltale signs of the cosmic microwave background and the distant galaxies receding from view, how will these astronomers of the far future discern the occurrence of the Big Bang?

According to Avi Loeb, a Harvard theorist, astronomers in the distant future of 1 trillion C.E. will still be able to deduce the Big Bang and the prevailing cosmological theory known as “lambda-cold dark matter” or LCDM. To achieve this, they will need to utilize the most remote source of light available to them, which are hypervelocity stars that have been expelled from the center of Milkomeda.

Loeb, who is the director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, stated, “Previously, we believed that observational cosmology would not be feasible in a trillion years. However, we now know that this will not be the case. Hypervelocity stars will enable residents of Milkomeda to gain knowledge about cosmic expansion and reconstruct the past.”

Approximately every 100,000 years, a binary-star system comes too close to the black hole at the center of our galaxy and is torn apart. One star plunges into the black hole, while the other is propelled outward at a speed exceeding 1 million miles per hour, ultimately being expelled from the galaxy altogether.

Detecting these hypervelocity stars is more challenging than finding a needle in a haystack, but future astronomers will have a compelling reason to diligently search for them. Once these stars move far enough away from Milkomeda’s gravitational pull, they will experience acceleration due to the expansion of the universe. Astronomers will be able to measure this acceleration using more advanced technologies than what we currently possess. This will provide an additional piece of evidence for an expanding universe, similar to Hubble’s discovery, albeit more challenging due to the minute effect being measured.

By studying stars within Milkomeda, astronomers will be able to infer the time of the galaxy’s formation. By combining this information with measurements of hypervelocity stars, they can calculate the age of the universe and significant cosmological parameters such as the value of the cosmological constant (the lambda in LCDM).

“In the future, astronomers will not need to rely solely on faith when it comes to the Big Bang. Through meticulous measurements and astute analysis, they will be able to uncover subtle evidence that outlines the history of the universe.”

This article is republished from PhysORG under a Creative Commons license. Read the original article.