The universe is believed to have originated about 13.8 billion years ago. The problem is that light from the most distant corners of it can reach us from a distance of 92 billion light-years. Both of these values ​​are quite contradictory.

It is worth emphasizing that – at least this is what the public knowledge shows – nothing can travel faster than light. In theory, this means that the size of the universe, expressed in light-years, should exactly match its radius. However, this is not the case, and the difference seems huge.

The phenomenon known as the expansion of the universe plays a key role in explaining this puzzle. The cosmic microwave background radiation that astrophysicists have been able to observe to this day originated in the Big Bang period. If the universe were static, the distance traveled by this radiation should be about 13.8 billion light-years. However, the universe is expanding, and its expansion not only does not slow down but even accelerates.

In 1929, Edwin Hubble recorded a relationship between the distance between galaxies and the speed at which they are moving away from each other. Milton Humason helped him in his discovery, and both scientists led to the creation of concepts such as the Big Bang or the expansion of the universe. The rate of this expansion is now known as the Hubble constant.

The universe was most likely created around 13.8 billion years ago

Determining its value is an extremely problematic task. Scientists use various methods to help them calculate the Hubble constant. Data obtained from analyzes of cosmic microwave background radiation suggest that its value should be 67.4 kilometers per second per megaparsec. The problem is that star-observing telescopes suggest the Hubble constant is 73.4 kilometers per second per megaparsec.

Either way, one thing is for sure. The universe is not static but is constantly expanding. It is not known whether the pace of this phenomenon is constant or variable, or even if the universe may shrink. As for the conundrum we wrote about in the title, its explanation seems quite simple and it was provided by Edwin Hubble almost 100 years ago.