(ORDO NEWS) — In the age of high technology, we don’t think about old household appliances. And even more so about old, huge TVs. Their place is now taken by flat black rectangles with LCD screens. But what if we underestimate the older generation of TVs? After all, they are equipped with antennas for receiving broadcast signals, which is certainly extremely archaic by modern standards. However, these antennas are, in a sense, a very specific type of radio telescope and can be used by scientists to … detect the Big Bang.
For countless generations, philosophers, theologians, and poets have speculated about our cosmic origins with a variety of hypotheses. Everything changed in the 20th century when theoretical, experimental, and observational discoveries in physics and astronomy finally.
How was the universe born?
Scientists now know that a combination of cosmic expansion, the primordial abundance of light elements, the large-scale structure of the universe, and the cosmic microwave background combined to create the Big Bang. Although the cosmic microwave background (relic radiation) was only discovered in the mid-1960s, an attentive observer might find it in the most unexpected places, such as an old television.
CMB is a cosmic microwave background radiation that originated in the early universe shortly after the Big Bang
The fact that galaxies at different distances exhibit different properties was the first clue for researchers, which led them to the idea of the Big Bang. However, the most important evidence supporting this landmark event did not come to light until the mid-1960s.
To understand how everything works, you need to understand what relict radiation (cosmic background microwave radiation) is. Today, the first thing that catches your eye while studying the Universe is galaxies, or rather a myriad of them: scientists see approximately 2 trillion. And this is according to the best modern estimates. Galaxies near the Milky Way are very similar to each other: they are filled with stars similar to the stars in our galaxy. But what about the laws of physics?
It is logical to assume that the laws of physics in other galaxies are the same as in ours. Their stars should also be made of protons, neutrons, and electrons, and their atoms would obey the same quantum laws as the atoms in the Milky Way. However, there is a slight difference in the lighting we get. Instead of the same atomic spectral lines, we find here at home, light from stars in other galaxies shows displaced atomic transitions.
Each element in the universe has its own unique set of atomic transitions that correspond to a specific set of spectral lines. We can observe these lines in galaxies other than our own, but while the pattern is the same, the lines we observe are systematically offset from the lines we create with atoms on Earth. These shifts are unique for each particular galaxy, but they all follow a certain pattern: the further away a galaxy is (on average), the greater the shift of its spectral lines towards the red part of the spectrum. The further we look, the more shifts we see.
Spectral lines occur when light waves of certain colors are absorbed. According to Forbes, the light may be shifted because these galaxies were rapidly moving away from the Big Bang. Hubble’s initial observations of the expansion of the Universe in 1929 were followed later by … [+] more detailed, but also uncertain observations. The Hubble plot clearly shows the redshift versus distance ratio with superior data compared to its predecessors and competitors; modern equivalents go much further. Note that special speeds are always present, even at large distances, but that the general trend linking distance to redshift is the dominant effect.
This last point turned out to be in full agreement with our observations and helped us understand that the fabric of space itself is expanding over time. The reason light turns redder the further we look is because the universe is expanding over time, and the light within that universe gets its wavelength stretched out by the expansion. The longer the light has traveled, the greater the redshift due to expansion. As we move forward in time, the emitted light shifts to longer wavelengths, which have lower temperatures and lower energies. But this means that if we look at the universe oppositely – imagining it as it was in the distant past – we will see light at shorter wavelengths, with higher temperatures and higher energies. The further you extrapolate,
As the fabric of the universe expands, the wavelengths of any radiation present will stretch. This is true for both gravitational waves and electromagnetic waves; any form of radiation has its wavelength stretched out (and loses energy) as the universe expands. As we go deeper into the past, radiation should appear at shorter wavelengths, higher energies, and higher temperatures.
Although this was an exciting theoretical leap, scientists (starting with George Gamow in the 1940s) began to extrapolate this property further and further until a critical threshold of several thousand Kelvin was reached. At this point, as the reasoning followed, the radiation present would be energetic enough for some of the individual photons to ionize neutral hydrogen atoms: the building block of stars and the primary content of our universe.
When you move from a universe that was above this temperature threshold to one that was below it, the universe goes from a state filled with ionized nuclei and electrons to a state filled with neutral atoms. When the matter is ionized, it is scattered by radiation; when the matter is neutral, radiation passes directly through these atoms. This transition marks a critical moment in the past of our universe.
After the formation of neutral atoms, due to the cooling of the Universe below a certain critical threshold, the photons of light move in a straight line, which is affected only by the wavelength of the expansion of space. The spectacular realization of this scenario is that today this radiation would have cooled from a few thousand Kelvin to just a few degrees above absolute zero since the universe should have expanded anywhere from a hundred to several thousand times since that era. Even today, it should remain a background that comes to us from all sides in space. It must have a certain set of spectral properties: the distribution of a black body. And it has to be found somewhere in the microwave to the radio frequency range.
Remember, light as we know it is much more than just the visible part to which our eyes are sensitive. Light comes in different wavelengths, frequencies, and energies. What was ultraviolet, visible, and infrared light billions of years ago is becoming microwave and radio radiation.
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