Age of universe is said to be about 13 billion years. It can be estimated using the Radio-activity in a piece of rock. The entire universe was said to be contained in an atom 13 billion years ago. An explosion occurred (big bang) and the entire universe was thrown out and started spreading. The universe continuous to expand even today.
Age of the earth is around 4.5 billion years. It is born out of sun and belongs to the solar family. It has undergone so many changes since its birth. Even old continents have gone and new continents have formed.
The first man had appeared around 2.5 million years ago. The first single cell life appeared in the ocean and evolved into intelligent human beings according to Darwin's theory.
The mutations and environment necessity made us. We are now dominating the world in using its resources.
Pyramids were built 4500 years ago around 2500 B.C. Such a large structure built so long time ago; before mathematics and engineering is a wonder. A first monument for mankind.
Average age of man is around 80 years. It continuous to increase due to rapid development of medical science. It may soon cross 100 years.
We know one day is 24 hours. Time taken by the earth to spin once. Our body has adopted to day and night cycle of the earth.
The light takes 8 minutes and 20 seconds to travel from the sun to earth. But moonlight takes only 1.3 seconds to reach us.
It means whatever happens in the sun will reach us only after a delay of 8 minutes.
The heart pumps liters of blood throughout the body continuously. It beats for every second (resting time). So we can take one beat roughly as one second.
Sound waves moves in millisecond time where as radio waves travel in microsecond time.(also light). Hence lightning appears first and then thunder is heard.
Atoms and molecules can rotate and vibrate due to thermal energy. They roughly take 10^-12 second for one rotation and 10^-15 second for one vibration.
Light takes 10^-18 second to cross an atom and 10^-24 second to cross a nucleus. The smallest distance possible.
Is there any bigger times or smaller time intervals other than what is listed above? We do not know.
Is there any common measuring tool for the entire range? Yes, the radioactivity. An element after emitting the radiation becomes another element. For example, Radium may become thorium and lead. So there is a life-time for every radioactive element. The average life-time of radioactive element ranges from billion years to nano-second or even less. Hence mean life-time of radio-elements is a good tool to measure the entire range of time.
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