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Discovering the Smallest and the Largest – The Story of the Size of the Universe

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From Plato’s Cave into the Wide Open

The Greek philosopher, Plato, explained how most humans are like prisoners in a dark cave. Such a person cannot see much in the darkness and believes the whole universe to be full of small dark shadows. It is only when the person gets out of the cave and into the bright sunlight that the person becomes aware of the universe’s vastness.

Humans are like this person in a cave. For most of our history, we have not been aware of the universe’s incredible scale from the smallest to the largest. It is only with the advent of telescopes and microscopes that we have been able to “improve” our eyesight and “see” the universe for what it is.

Multiplying by Powers of 10

Every day people are mostly aware of objects that are approximately close to our human sizes. The average Indian height is 5.8 feet (1.77 meters) for men and 5.3 feet (1.62 meters) for women. Let us approximate this as close to 1 meter. Scientists and mathematicians write this as 100 meters.

A Blue whale, one of the largest animals, is 10 times our size, so 101 meters. If we multiply this by 10 again, we reach 100 meters. This is how much Usain Bolt ran in the Olympics in 9.58 seconds. This multiplying by 10 and then writing the size as 102 or 103 is called counting in the powers of ten.

Thus, if we multiply our human size by 6 powers of 10, we reach the distance between Mumbai and Delhi, which is 1,400 km. This is written as approximately 106 meters.

As humans began to use telescopes, they realized that cosmic distances were truly immense. The distance between the earth and the Sun is 1011 meters. This is still a tiny distance in terms of the universe’s size, but by our human scales, it is almost unimaginable. It is akin to going from Mumbai to Delhi one billion times. If you made one trip a day, this would take you 27 thousand centuries to complete.

The distance to the next set of stars, Alpha Centauri A and B, is 1016 meters. It takes light 4.24 years to reach us from these stars. As humans continued their discovery of galaxies, they found that, like humans, stars also have a lifecycle. Stars and born, and they die. Scientists also discovered the incredible fact that the atoms of which we are made are primarily made in giant explosions called Supernovas. Supernovas occur when certain types of stars end their lives and explode with an enormous sound and light show.

The Hubble telescope that was put into orbit around the earth has captured some of the most beautiful pictures of the vast universe. The furthest we have been able to see is around 1025 meters. It is hard, even for experienced astronomers, to come to grips with this immense size.

Through the use of our incredible telescopic instruments, we have discovered that there are other planets (called exo-planets) that go around other stars as we go around our Sun. That some of these exo-planets have an atmosphere and water and could also harbor life is tremendously exciting. It is no longer science fiction to one day receive a message from an alien civilization in the skies!

Dividing by powers of 10

Just as telescopes gave us super-human eyesight to see the distant stars, microscopes gave us the capability to see the very small.

Once again, starting our journey with our human size, 100 meters, let’s first divide by 10. In the scientific notation, this is written as 10-1 meters. This is 10 centimeters and is around the size of your palm. This is also the size of your calculator or pen. Dividend again by 10, and you reach 10-2 meters. This is 1 centimeter. This is the size of one key on your laptop and a small insect. Dividing this by 10,000, we reach 10-6 meters. This is the size of a human cell.

Cells are the building blocks of all life on earth. They are like mini-cities, with a power station” that converts food into fuel, “roads” along which molecules travel, and a nucleus, inside of which the cell contains information about reproduction.

Dividing the size of a cell by 100 and we reach 10-8 meters. This is the size of our DNA. Human DNA is a molecule whose atoms and twist around each other in a double helix shape. It contains all the information and instructions to make us.

Dividing again by 100 and we arrive at the surface of atoms (10-10 meters). The existence of atoms was once only speculation. It was Einstein who provided a theoretical basis for the existence of atoms, and today, we can “see” pictures of atoms using special electron microscopes.

To investigate particles even smaller than an atom, we now use the Large Hadron Collider (“LHC”). This is a high-energy particle collider. It smashes small particles together to create even smaller particles which it then examines and measures. This was built by the European Organization for Nuclear Research (CERN), and India is an invited, contributing member with a number of Indian scientists working at CERN. The LHC is in a tunnel 27 kilometers long and located on the France–Switzerland border near Geneva.

Using the LHC we have discovered particles that are astonishingly small. An atom is made up of electrons, protons, and neutrons. The proton and neutron are themselves made up of smaller particles called quarks. 10-15 meters is around the smallest the LHC can “see”. the physics rules by which our everyday world function no longer applies at these small sizes, and we are still learning more about how particles at this smallest part of the universe work.

Still so much to discover

There is still so much to discover, and the size of the universe, from the smallest to the largest, is almost incomprehensible. It is perhaps best to keep in mind what the great physicist and mathematician Isaac Newton said:

“I do not know what I may appear to the world, but to myself, I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.” Our human adventure discovering more about the universe continues.

© Kaikhushru Taraporevala

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