• Suman Srivastava

#TIL - The Power Of An Inquisitive Mind

Updated: 3 days ago

Where did I come from? From Mummy’s tummy. Where did Mummy come from? And her Mummy? Where did the first human come from? The first living being? Who created the earth? Who created God? Where does the sun go at night?

Every child has asked those questions. Some grown men have continued to ask these and other follow up questions. This is the story of what those men have found. It is the story of how at each stage there was a perfectly good explanation, except for that one irritating fact. That one little problem that the theory does not explain. That led, in due course, to a new theory. Then another irritating fact came up. New theory again. Until finally...

Ancient Science

Early man looked up at the sky and wondered why the sun & the moon rose and set everyday. In every civilisation, humans came up with a theory that explained this. It usually involved gods going across the sky. Every time humans discovered a new phenomenon, they had to invent a new story. For example, they noticed a lunar eclipse and so they needed a story about a demon eating up the moon, but then having his head cut off, so that the moon could be saved.

We call those theories myths. But they were the best that early humans could do. However, they were pretty smart and started to notice some things. For example, that when a ship sailed away from a port, first the lowest parts would disappear from view, and the mast would be the last thing to be seen.

One guy wondered why that would be, and came up with the theory that the earth was round. Another person noticed that the sun lit up a well in one place perfectly on one particular day of the year (we would call this the summer solstice), but not on other days of the year. So he measured the angle that the sun made in the city where he lived on that particular day and the distance of his city from this well. Using simple trigonometry, he was then able to work out the size of the earth. He was within 2% of the right answer, which is brilliant considering the tools that he had at his disposal.

So now we knew that the earth was round and we could see that the sun and the moon moved around it. However, we had to explain why the sun wandered around the sky during a year, and why the moon waxed and waned in a month. So they came up with an elaborate theory about rings around the earth. Each of the heavenly bodies had its own ring and travelled on it. The stars were stationary in the sky. Seemed pretty good to everyone.

Until people noticed some stars wandering around. These wandering stars were called planets (apparently the word ‘planet’ means ‘wandering star’ in Greek). They were on one side of the sky at times, and on the opposite side at other times. This didn’t fit well with the theory of the circles around the earth.

So somebody worked out that the earth and the planets were actually going around the sun. So earth was not the center of the universe after all. The sun was. The planets had their own - circular - orbits. People used trigonometry to work out the distance from the earth to the sun and the moon, and the order of the orbits of the planets around the sun.

This theory seemed fine and explained a lot of things about the wandering sun and the planets. But the question arose, what was keeping the planets going around the sun? And for that matter, what was keeping us glued to the earth when it was spherical? Have you thought about people in the Southern Hemisphere hanging upside down?

Science Breaks Free

A smart human called Newton came up with the theory of gravity and provided equations that explained everything from why apples fall down and not fall up, to why planets go around the sun. He was hailed as a genius. His equations seemed perfect, except for one little thing. Mercury seemed to be rotating on an orbit which was a little different from what Newton had predicted. People thought that maybe there was another planet between Mercury and the sun, which was pulling Mercury and hence causing the deviation. But Einstein came along and changed Newton’s equations. His new equations explained Mercury’s path as well as that of all the planets perfectly. Hallelujah. All was well.

Well not so. Long ago, one extra inquisitive guy had noticed that even the other stars (the non planets) seemed to move by a little bit and weren’t just standing in place. So humans figured that stars were other suns, just that they appeared faint because they were so far away. Just how far away were they?

At first we weren’t sure of the absolute distance, but we figured that the brighter stars were closer to us and the fainter stars were further away. So we measured the relative brightness of stars and worked out the relative distances of these stars from each other. Now if we could figure out how far one of them was, we would know the distance to all the stars. Well, even that was done by the invention of better equipment and by a really smart guy in the 19th century. He worked out the distance to a nearby star (called 61 Cyngi). Now we knew the distance to all the stars. Or did we?

There seemed to be a lot of stars, millions of them, and we could see them in one nice band that we decided to call the Milky Way. Then, as our telescopes improved, we noticed something that we had thought were clouds in space. These clouds turned out to be lots of stars, only they were really far away. So far away, that they were in another galaxy. Turns out that the Milky Way is just one of many galaxies in the universe. Each galaxy seems to have millions of stars.

Not only were there lots of galaxies with lots of stars, all these were moving. At first we thought they were all moving randomly across space, but then a smart human was able to work out that all these galaxies were moving away from us. It’s almost as if we had bad odour and all the stars were fleeing away from us. Why?

Einstein to the rescue again. Well, sort of. His equations did explain the movement of the galaxies and their moving away from each other. But, at first, he thought he was wrong. He thought the universe was constant and eternal. His equations told him that the universe was constantly changing and had started from a particular point. He needed other scientists to show him the error and even then he was not convinced. When he finally recognised his mistake, he called it the biggest blunder that he had ever made.

Anyway, its all sorted now. We can imagine the universe to be like a balloon that is getting bigger and bigger. The balloon has lots of spots on it. Each spot represents a galaxy. As the balloon gets bigger, the spots get bigger too and also move apart from each other. That explains the movement of the galaxies.

Now that we know they are moving, we can wind the clock back and try to work out where they came from. You know the story. All the matter was in one tiny point and then there was a “Big Bang” and all this matter exploded, formed the galaxies, the stars and the planets, and on one of those planets of one of those stars in one of those galaxies, life started, and here we are now. This sounds quite simple, but isn’t. Let me introduce you to some of the questions that arise.

Science Gets Into Overdrive

The universe has a peculiar composition. Most of it is just empty space. Of the bits that is matter, almost all is Hydrogen and Helium. The proportion of the elements in the universe is as follows:

Hydrogen: 10,000

Helium: 1,000

Oxygen 6

Carbon 1

All else 1

How weird is this? When you look at the earth, we find very little Hydrogen and even less Helium. The Hydrogen that does exist are all in compounds (in water, for instance). Meanwhile, we have lots of other elements, nitrogen, iron, silicon, and so many others. To think that all of these elements together are just a rounding off error in the universe! Wow!

Wait a moment, you say. How do we know this? We haven’t been everywhere. Well, these humans are really smart. We have been interrogating something that has been all over the universe and has been travelling since the beginning of time. That something is called light. It is amazing how much information light carries. We can not only “see” things, we can also use it to work out how far away a particular star is from us. Then we look at the tinge on the light and work out whether it is moving towards us or away from us (red tinge means it is moving away - the degree of redness indicates how fast). By analysing the spectrum of the light waves, we can figure out what elements exist in the place the light is coming from. Finally, light is a time traveller and tells us what happened in the past. It is like we got one witness to tell us the whole story. But boy, is it a good witness.

So let’s get back to the elements in the matter. (Oh, by the way, there is also dark matter and dark energy in the universe, which is even more peculiar. We won’t worry about that just yet, because it is hard enough to understand why the elements are the way they are, and how they came to be.)

Turns out that when you turn the clock back and get all the matter in the universe closer together, the pressure builds up. And the smaller the space, the more the heat. Turns out that if all the matter were in a single point, then the temperature would be in the billions of degrees. At the moment of the Big Bang, there was immense temperature and pressure all concentrated in one really tiny point. We aren’t quite sure what caused the bang, or even if there was a bang, since the laws of physics don’t work at that point.

However, we do know what happened from a billionth of a billionth of a billionth of a billionth of a billionth of a second (10^-47 of a second) after the Big Bang. What happened was that all the matter spilt out of the point in a dense soup. Extremely dense and extremely hot. Once released from the point, the matter started to expand rapidly and also cool down rapidly. Within one second, the temperature had dropped from billions of degrees centigrade to merely millions. At this temperature, protons and electrons started to combine and form Hydrogen.

The temperature continued to fall and the matter continued to expand. At around the three minute mark, some of the Hydrogen molecules started to combine and form Helium. That was a big event, but then nothing major happened for 300,000 years. This soup of Hydrogen and Helium continued to cool down, but was still so hot and thick that even light could not escape it.

Then the cooling soup started to congeal in lumps. For the next 100 million years, these lumps kept getting bigger and bigger. As they got bigger, they attracted more matter to itself and kept getting even bigger. The lumps would become so big and so dense that some of the Hydrogen and Helium started to combine in a nuclear reaction that started to generate a lot of heat and light. A star was born.

For the next 4 billion years, the universe was basically a nursery of stars. More and more stars were born. Billions of them. These stars were burning Hydrogen into Helium. The two were combining again to produce a few other elements, but not yet the heavier ones like oxygen, iron and so on. So where did those come from?

Turns out that soon after the Big Bang, only Hydrogen and Helium were formed. The conditions weren’t right for the production of any of the other elements. Even in the first set of stars, the conditions were right only for a few other light elements. Then something spectacular started to happen.

The first generation of stars started dying. At some point, these stars run out of Hydrogen to burn. When that happens, they start to collapse. As they collapse, the matter gets concentrated and starts a second nuclear reaction. This time much hotter than the first one. Depending on how much mass was there in that particular star to begin with, the second reaction could result in stars that we call white dwarfs, neutron stars and black holes. Finally, after all the fuel runs out, the star tends to explode in spectacular fashion creating what we call a supernova.

Now when the stars have the second (and sometimes third reactions), they become hotter and conditions are now favourable for creating the heavier elements. Iron, Oxygen, Carbon etc. And when the star explodes, these elements get thrown out into the surrounding areas. Some of these elements get gobbled up by another star, which itself starts to grow. Since it starts with some of the heavier elements, it is able to create more heavy elements. And when it explodes, more elements are strewn about.

Our star, the sun, is a third generation star. It has many elements in it. More importantly, there was a lot of heavy elements lying around which coalesced into planets due to the gravitational pull of the sun. One of those planets is the one we live on.

So it took around 8 billion years to get from the Big Bang to the formation of the earth. All the elements are here now. All the carbon, the oxygen, the water. All it needed now were some small miracles. A planet that’s really hot on the inside. That has exactly the right amount of mass so that it can hold the atmosphere. Has enough water on the surface. The conditions were just right for life to emerge.

It took around three and a half billion years after the earth was formed for the first living creature to appear. This was probably deep in one of the oceans, near a volcanic vent. Nice hot lava coming out of the earth. Lots of water. Miracle happened.

Another billion years and that first creature has evolved into a human being. One who can ask all those questions. One who has the brains to answer a lot of them. Quite a miracle when you think of it.

Miracle that the universe is the way it is. One scientist dude has worked out that our universe is the result of 6 numbers - numbers like the force of gravity, the strength of the strong nuclear force and the weak nuclear force and so on. If any of those numbers were slightly more or slightly less, then our universe wouldn’t have been created. At least not in this way.

What’s Next

Human beings have always had a tendency to bow to the crowd, take the applause and announce “mission accomplished”. Except there’s always that one little thing. That thing that doesn’t fit.

For all the completeness of the story above, there are a lot of loose ends. To begin with, the whole story above is all about matter. We understand matter fairly well. We also understand energy quite well. We even know how the two are related (Einstein’s famous equation: E=MC^2).

But matter/energy is less than one quarter of what’s in the universe. The rest were loosely called dark matter and dark energy. Basically because our witness, light, doesn’t tell us much about it. We know it’s there because of the way the galaxies and the stars move. Matter alone would not be able to create the gravitational forces necessary to keep all this moving in just the right way. However we don’t know very much more about dark matter.

There’s also this other funny thing. We know the laws that govern the Big bodies - the stars, planets, animals. We also know the laws that work at the sub atomic levels - What keeps the electrons, neutrons, protons and the rest behaving as they do. The funny thing is that these two laws contradict each other. Chances are that both are wrong and we need a new unified theory of everything. Scientists are searching for that now.

Isaac Asimov once said, “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ (I found it) but ‘That’s funny…’”

It seems our inquisitive minds will never be satisfied. We will always find something and say “that’s funny”. Cheers to this inquisitive mind.

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