Before we know the mass of the universe, we need to decide what kind of object we are talking about here. Advanced readers must know that about 69 percent of the total matter in the universe is dark energy or secret energy. About 26 percent is dark matter, and the remaining 5 percent is ordinary matter as we know it. The known universe around us is made up of these known common substances. But even reaching the pinnacle of science in the 21st century, we still don't know what dark matter and dark energy actually are. Therefore, when talking about the mass of the universe, there is no way without excluding them.
Second, scientists still think there's a lot of the universe we can't see. To be more precise, the universe's radius of about 46.5 billion light years is the boundary of our observable universe. That is, the diameter of the universe extends up to 93 billion light years. We have not seen anything beyond this till date. Because no light has reached us from the objects that are outside it. Because of this, scientists estimate that the size of the real universe is about 250 times larger than our observable universe. It is spread over another 7 trillion light-years. So the mass of the universe we are going to talk about is only the observable universe and only 5% of ordinary matter. This does not include dark matter, dark energy and unseen matter or matter.
But many will ask, is there any way to measure the mass of the universe? The universe is no longer oil-salt or potatoes, it is not a pot that can be weighed on a scale! Scientists have thought about the same question for a long time. While doing that, there was no way to measure directly with a scale, but they found an indirect way. For example, we do not have a way to directly measure the weight of the Earth or the Sun. But the mass of any planet-star can be accurately measured by indirect means. One such indirect method of measuring the mass of the universe is the cosmic microwave background radiation or CMB. Literally in Bengali it is called cosmic background radiation. But it can also be called the first light of the universe. There is a reason to say that.
After about 13 billion years, we can no longer see that light with the naked eye. Because its wavelength is extended to become photons in the microwave range
In fact, our universe began about 13.7 billion or 1,370 million years ago. This particular event is called the Big Bang. Then there was the reign of darkness in the universe for about 380 thousand years. Because the universe was still hot, atoms had not yet formed. Matter then existed in the plasma state. Protons, neutrons and electron particles were still not stable in extreme heat. Digvadik was running. Particles of light were trapped in this soup of particles. means photon. That is why the universe was covered in dark darkness. But 380,000 years after the big bang, the temperature of the universe decreased considerably. At this time, electron particles start to associate with protons. In this way hydrogen, helium and few other atoms are formed. As a result, for the first time, the photon is unhindered. This light started running around the universe. The universe became illuminated for the first time. That is why the CMB is called the Prothom-alo of the universe.
But after about 13 billion years, we can no longer see that light with the naked eye. Because its wavelength is extended to become photons in the microwave range. Hence its name microwave background radiation. However, this light cannot be seen with the naked eye but can be detected using modern technology detectors. Even your home television screen catches that light. One percent of the crackle or noise seen on the television without a channel is actually the light of that primordial universe. The first splash of light in the universe. In 1965, American scientists Arno Penzius and Robert Wilson accidentally detected that light for the first time. In recognition, he received the Nobel Prize in 1978.
Now the question is, how is the mass of the universe measured using the CMB? In fact, much of the early universe is known by analyzing the character of this background radiation. This Prothom-alo of the universe is spread almost evenly throughout the space. But it also has some fluctuation or instability. This instability depends on how much matter there is in the universe and what kind of matter there is. Light only interacts with the ordinary or known matter of the universe. Therefore, any change in the amount of such material also affects the CMB. It means that the character of the CMB coming to us also has signs of change. By calculating that effect or change, scientists determine the amount of common matter in the universe. Simply put, scientists measure the mass of the universe by uncovering this data from the CMB or background radiation.
By measuring the ratio of these elements in the planets and stars formed long ago in the universe, it can be calculated how much common matter was there during those reactions in the primitive universe. Apart from this, there are other methods of measuring the mass of the universe.
Another method of measuring the mass of the universe is to measure the ratio of elements in different planets and stars. For example, certain chemical reactions took place sometime after the Big Bang. This reaction depends on the amount of common substance. If the amount of matter was more in the primitive time of the universe, then more hydrogen and other elements including helium and lithium would have been formed in these chemical reactions.
By measuring the ratio of these elements in the planets and stars formed long ago in the universe, it can be calculated how much common matter was there during those reactions in the primitive universe. Apart from this, there are other methods of measuring the mass of the universe. All methods yielded more or less similar results.
These methods can actually determine the density of common matter in the universe. As seen, the tropic or critical density of the universe is about 10-26 kg/m3. This is equivalent to having about 6 protons per cubic meter. On the other hand, the volume of the observable universe is about 4×1080 cubic meters. As we know, mass is the product of density and volume. So multiplying the tropical density and volume of the universe gives 4×1054 kilograms or kg (54 zeros after the 1). This is the mass of our universe.
You must have understood in the discussion so far, this is not the actual mass of the universe. If the behavior of dark matter and dark energy is ever known, this may change. But unless it can be known, the true mass of the universe will remain an unsolved mystery.