It is possible that the 'first light of the Universe' observed in 2018 was caused by a technical fault in the sensors.
According to the findings of a team of specialists, the light of the 'cosmic dawn' has not yet been discovered.
Earlier this year, a team of researchers from Arizona State University (ASU) and the Massachusetts Institute of Technology (MIT) revealed the discovery of the first light in the Universe in two articles published in the journal 'Nature' (here and here). For another way of saying it, a signal that astronomers thought to be a ray of light from the first stars to develop, heralding a 'cosmic dawn' that lifted the entire Universe out of the darkness that had reigned over it since the Big Bang.

In a recent study published in the journal'Nature Astronomy,'researchers at the Raman Institute in India discovered that the signal from the Big Bang didn't actually correspond to the first light in the universe. According to other theories, the light was not light at all, and that it did not even originate in space, but rather in the device that was used to catch the image in the first place.

Although this is the case, the discovery is far from a letdown, as the signal described in 2018 exhibited a number of unanticipated properties that were extremely difficult to explain in light of existing theoretical understanding. To put it another way, a "new Physics" was required in order to completely comprehend it. Those measures will no longer be essential as a result of the newly obtained information.

"The researchers write in their study that their radiometer measurements of the radio sky spectrum in the 55–85 MHz band "show that the profile found by Bowman et al. in data taken with the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) low-band instrument it is not of astrophysical origin; its best profile is rejected with 95.3 percent certainty." It reinforces earlier concerns and shows that the profile discovered by Bowman et al. does not represent evidence of novel astrophysics or non-standard cosmology, as previously suggested."

the dawn of the cosmos
The 'cosmic dawn' or 'epoch of reionization' is an era in the history of the Universe that has been long sought after by scientists. It encompasses a period of time that ranges from 50 million to 1,000 million years after the Big Bang, depending on how the period is defined. In reality, before the first stars formed, our Universe was composed of a kind of dense and foggy cloud of extremely hot ionized gas, which made it impossible for light to flow through it at all.

After 380,000 years, the Universe had cooled down to the point that the original fog began to disperse, marking the end of the Big Bang. Protons and neutrons were then allowed to combine to form neutral hydrogen atoms, allowing the Universe to become 'transparent' and photons (the particles that make up light) to be able to flow freely through space for the first time in history. It was then that the first stars and galaxies were formed, their ultraviolet light gradually reionizing the ubiquitous neutral hydrogen and allowing the complete spectrum of electromagnetic energy to freely flow.

The process took a long time, but the Universe was totally reionized approximately 1,000 million years after the Big Bang occurred. And it is only from this location that our telescopes are able to observe anything, making the reionization process itself difficult to comprehend in its entirety. It was for this reason that detecting the light of the cosmic dawn was so critical. Something that would completely alter the course of events. And it is for this reason that the 2018 announcement had such a significant impact.

The use of a ruse signal
At the time, in fact, the scientists working on the EDGES experiment were hard at work searching for that signal at extremely low radio frequencies, and they were confident that they had discovered it, despite the fact that what they discovered was completely different from what they had anticipated. In reality, the signal's amplitude was nearly twice as large as that predicted, indicating that the hydrogen through which the signal travelled was significantly colder than expected, as previously stated. In addition, what could have been causing the hydrogen to cool at such a young stage in the history of the Universe? The only potential response was dark matter, but the properties of dark matter would have had to be considerably different from those predicted by current theories in order for this to be true. To put it another way, the alleged detection of the first light of the Universe threatened to bring down, one by one, some of the most fundamental predictions of physics concerning the early days of the Universe, much like a row of toppling dominoes. It was necessary to construct a new physics in order to properly comprehend what had occurred.

This prompted a large number of academics to attempt to validate the 2018 signal. Generally speaking, any unusual discovery in science, particularly if the discovery compels new scientific thinking, must be checked a thousand times before it can be regarded as valid. Therefore, scientists at the Raman Institute, lead by Saurabh Singh, agreed in 2020 to test the signal with a radiometer called the Shaped Antenna Measurement of the Background Radio Spectrum 3 (SARAS 3) in order to see if it could be verified. However, despite spending more than a year collecting and analyzing the data, they were unable to detect any signal at all.

"More importantly, the correlation analysis reveals that the distortion present in a spectrum created by the EDGES low-band instrument, which was used to derive the best-fit profile and define the parameters space bounds for a profile, is not present in the SARAS 3 sky spectrum," the researchers write. Considering the foregoing, it appears that the considerable spectral distortion observed in the sky spectrum measured with the EDGES low-band instrument is a systematic inaccuracy connected with the device."

In other words, the error caused by the EDGES antenna itself, rather than a signal from the farthest regions of space-time, was responsible for the detection in 2018. Of course, the data from this current study will need to be verified as well before the finding from three years ago can be ruled out completely. And more observations with more instruments are required in order to do this.

"We come to a close," Singh and his colleagues write "It is hoped that by continuing observations with sensors deployed in such environments as the SARAS 3 monocone in large bodies of water in remote locations on Earth or a space mission orbiting the far side of the Moon, they will be able to provide data free of systematics, which will lead to the discovery of the true 21-centimeter redshifted signal of the cosmic dawn."

At the very least, it will no longer be necessary to develop new physics in order to explain a signal that, in the light of our work, looks to be nothing more than a random noise. Meanwhile, the genuine sign of the cosmic dawn, the first light of the Universe, is still out there waiting to be discovered by some lucky soul.