It’s human nature to ask questions and try to find the answers. There are many questions which are always asked, and people have tried to answer them throughout our history. And there are many questions to which we do not yet have answers, at least satisfactory ones.
One of these questions is about the origin of the universe. Everyone wonders how this all began. How did the universe begin? Or has it existed forever? What was there before it all began?
Current scientific understanding points us toward the fact that our universe has not existed forever; it had a beginning. It started with a big explosion popularly known as the ?Big Bang? about 13.8 billion years ago.
Many people, scientists among them, are not very happy with the idea that the universe had a beginning. They have tried to come up with some alternative ideas, some positing that our universe has always been in its current state. Nonetheless, experimental observation does not support these theses. The evidence seems to indicate that we had a beginning.
How do scientists come to such conclusions? Here is one example:
We see clusters of stars called galaxies in the sky. One of the perks of living in rural America is that we can see thousands of stars in the night sky even with our naked eye. Scientists can measure whether these galaxies are stationary, moving away from us or each other, or moving closer to each other.
Measurements currently show these galaxies moving away from each other. Thus, in the past, they were closer together than they are today. If we trace back, then, about 13.8 billion years, everything was confined in a very small point in space with infinite density. Many other experimental observations also point to the same conclusion.
We generally think that time is an absolute thing without any start or end. It is difficult to realize that time is only defined within the universe; there was no time before the Big Bang. Time also started with the Big Bang, so, as strange as it sounds, it does not make sense to ask what came before it. There was no space. There was no time.
Our current understanding of science mostly explains what happened after the Big Bang, but one of the gifts of science is that there surely are many secrets to be discovered. Scientists generally agree that after an initial explosion, our universe expanded rapidly and gradually cooled enough for energy to become matter.
For a few millionths of a second, shortly after the Big Bang, the universe was filled with a hot dense soup of free quarks and gluons called quark gluon plasma, cooling into normal nuclear matter like protons and neutrons.
Great clouds of hydrogen swirled around space until gravity pulled some atoms so closely together that they began to burn as stars. Stars swirled together in giant clusters called galaxies; now there are galaxies numbering in the billions.
As each star burned up all its matter, it died in a huge explosion. The explosion generated so much heat that some atoms fused, becoming more and more complex and forming the many different elements we observe today.
WHEN SOMETHING HAS A BEGINNING, it?s natural to think about the end. Does our universe also have an end?
Like so many, this question is not easy to answer. It is possible that the universe will last forever, or it could have a ?big crunch? as some scientists have predicted. For the next several billions years, don?t worry. It?s not going anywhere.
