How can the ages of our planet and the universe be so precisely determined?

It is now common knowledge that the earth is about 4.5 billion years old and life was not born until about a billion years after that. Of course, the universe itself is much older. It is currently estimated to be 14 billion years old. These are very long periods of time, and most people cannot even imagine them. For example, as a simplistic analogy, if all life on earth were to shrink to 24 hours, we humans would not be in it for one second.

Such a long time naturally brings a certain skepticism. Many people wonder how scientists actually arrived at these numbers. After all, fossils from the time our planet formed are unlikely to be found, and carbon dating cannot be used because organic compounds did not exist at that time.

naše planeta je starší, než si většina lidí myslí

However, the old familiar radiation may help. It is well known that every radioactive isotope has a certain decay time, i.e., the time it takes to lose its radioactivity. These times are of course well known today because they can be measured very easily under laboratory conditions. But how does this help us?

It is relatively simple. There are isotopes with half-lives on the order of billions of years. By studying them, or rather by studying how many have not yet been converted, the minimum age of the earth can be determined fairly accurately.

dnes dokážeme zjistit i stáří vesmíru

The universe itself is more complex. Here we use something called redshift. Simply put, a signal traveling over a really long distance (thousands of light years or more) is redshifted from our perspective. During that journey, the signal shifts closer to the red spectrum. And the greater the redshift, the longer the distance traveled, and the older the signal.

Therefore, we can only analyze the cosmic noise that is constantly streaming toward us and its redshift. Those with the greatest redshifts are those that have traveled the longest to us and are therefore the oldest. We can then use that calculation to determine their age and determine the minimum age of the universe.Of course, these are not perfect methods, but they give us a fairly accurate idea of how old our universe and the things around us are. And this would be useful for further research.