Brief Answers To The Big Questions by Stephen Hawking
Tags: books
Published: 2021-02-28 20:09:31

I generally like to write my afterthoughts on each chapter of the book. Here are some of the key takeaways I took from the book. 

**My Key Takeaways from the book**
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- **Is there a god?**

    In this chapter, Hawking used religion and science contradictions to explain the process of making the universe or the origin of the universe. For scientists like Hawking and Einstein, the word "god" doesn't means a human figure with whom you can attach personal feelings or relationships. The word "god" simply means the laws of nature. Hawking explained that you basically need three things to create a universe: mass, energy, and space. Einstein had already proved that mass and energy are basically the same things with the help of the famous equation E=MC^2. So, you only need two things, energy, and space. With the big bang, space came into existence like blowing up a giant balloon. For energy, he used an analogy to explain it. Imagine you want to create a hill on a flat surface. You dig up a hole to create a hill. Hill is a universe and a hole you dug up is negative energy. According to Hawking, you see positive energy in mass and energy we see today, but the negative energy is in space, which sounds odd, but it is true. Positive and negative energy balance out and adds up to zero and it's another law of nature. Hawking later says that if everything adds up to zero, then we might don't even need a god. 

    Something has to happen for something to happen. You can't just click your fingers and coffee present itself. You have to make it, right? Hawking says, 

    > The laws of nature itself tell us that not only could the universe have popped into existence without any assistance, like a proton, and have required nothing in terms of energy, but also that it is possible that nothing caused the Big Bang. Nothing

    Hawking compares the big bang to be as a black hole from which light can't even escape its gravity. Also, time. Time doesn't exist in the black hole. So, if the universe started from the big bang, there was no existence of time before that. So, even God didn't have time to trigger it. It's like asking for the edge of the earth, where there is no edge to a spherical object. So, it's a futile exercise to think that God created the universe. Wow!


- **How did it all begin?**

    In this chapter, Hawking tried to explain whether the universe has a beginning or an eternal history with boundary or not using Einstein and other physicists' work. Einstein proved many years ago that space and time are not absolute, but rather dynamic. They are only defined within the universe, so it doesn't make sense to talk about a time before the universe began. In the twentieth century, we found out that the universe is expanding and the objects far from us are expanding at a much higher rate. It shows that there must a point when the universe was not expanding and when everything was compact. That is the beginning of this universe, which was about 15 billion years ago. Hawking and Roger Penrose prove geometrically that the universe has a beginning. 

    Later in the chapter, Hawking said that we could predict the past the same way we can predict the future using Werner Heisenberg's Uncertainty principle, which says that no one can predict both position and speed of the matter. Einstein objected to the idea of uncertainty.  As he puts it nicely, "*God does not play dice*". God is a gambler because, when the universe is big, there are a very large number of rolls, so the result averages out to something one can predict. 

    Hawking proposed a no-boundary proposal, which states that the universe does have a beginning, but doesn't have a boundary. 

    > According to the no-boundary proposal, asking what came before the Big Bang is meaningless- like asking what is south of the south pole- because there is no notion of time available to refer to. The concept of time only exists within our universe.

    Wondering on a personal note: This all makes sense when you think about multiverse ideas. There are many universes that have a beginning and are constantly expanding. The idea of time and space is limited within our universe and there was no time before the beginning of the universe. 

![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/8nbimar2z9t3it5ijcdh.jpg)

- **Is there another intelligent life in the universe?**

    A human body has two main elements. A gene that provides the sets of instructions and a metabolism that aims to carry out those instructions. Our body has about 100 million bits of useful information in our genes. The evolution in the genes occurs around every 10,000 years. There are a lot of possibilities that our evolution would be disrupted by ourselves or the natural event and we won't be able to evolve into something that will take us to other galaxies. Some of the events include that we become so intelligent that we destruct ourselves, another meteorite hits the earth and wipes out mankind resulting in starting the process of making multi-cellular organisms from bacteria or any other single-cell organism. It is possible that in the future, we will be able to genetically enhance ourselves and become superhumans. Or is it possible that we nuke ourselves out? 

    Stephen described two ways of finding out whether stars have planets orbiting around them. One way is to measure the amount of light coming from another star. If the planet comes in a way, then the light from the star would get dimmable a little bit. If this occurs on a regular basis, then it means that there is a planet revolving around that star. Another way is to measure the position of the star and if the star slightly wobbles repeatedly then it means that there is a planet in an orbit that is making a star wobble due to its gravitational force. 

    Stephen also listed out some of the possibilities in the chapter to explain why we haven't visited by the aliens, which are convincing on an emotional note and also make sense. One of the possibilities, says that we might be the only life in the whole galaxy, which makes me wonder that if that's the case then we would probably be never visited by aliens because it would take around 50,000 years to travel from one galaxy to another, as stated by Hawking, therefore, life would have to genetically engineer themselves to live for great amounts of time to cover that travel. It would be a long trip into the dark. 


- **Can we predict the future?**

    It is possible to predict the future to some extent in the theory, but it is impossible in reality due to complex calculations and equations. Heisenberg's principle says that we cannot predict the position and speed of a particle. It is random. But we could measure the combination of both speed and position of the particle. In quantum mechanics, the particles don't have well-defined positions and speeds, rather they have a wave function. A wave function is a number at each point of space and the size of a wave function gives a probability that the particle will be found in that position. 


- **What is inside a black hole?**

    The biggest thing I learned in this chapter is that a human cannot survive while going into small black holes the size of our sun, but can survive while going into larger black holes. A smaller black hole will put more pressure or attraction on your feet than your head which will result in you becoming a spaghetti. But in the larger black holes, the force of attraction is equal which will make you survive in the entering of the black hole. But once you are inside a black hole, you will be crushed by the singularity. A star collapsed and forms into a black hole. There is a point in a black hole which is called singularity where space-time bend is infinite. Even Einstein's laws don't apply to singularity. 

    The Earth's escape velocity is 11 km/s and the sun's escape velocity is 617 km/s which is nothing as compared to the speed of light, which is 300,000 km/s. So light can easily escape the Earth because its speed is larger than the Earth's escape velocity. But imagine a bigger celestial object which is denser and bigger than Earth, a black hole. Light can't even escape a black hole because its escape velocity is much larger than the speed of light. Surprisingly, the escape velocity of the black hole is not listed in the book. Anyways, since light can't escape a black hole, therefore, a black hole doesn't reflect back any light and seems to be black. 

    The boundary of the black hole is known as the event horizon and Hawking made a discovery that the area of an event horizon always increases as more matter and radiation falls into the black hole. So if two black holes collide, then the surface area of an event horizon of a result black hole would be greater than the original black hole. 

    Hawking also discovered that black holes do emit swallowed matter in the form of radiation at a very slow rate. It is believed that the information from those released matter is lost forever, which doesn't support existing laws. This created an information paradox and scientists have been struggling for 40 years with this paradox. 

![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/dcdbf2k32cnew6uxvv41.jpg)

- **Is time travel possible?**

    In this chapter, Hawking mostly talked about the wormholes and space-time bending which is already explained in the previous chapters. One thing that I didn't know that we have a tested Einstein's general theory of relativity and we have experimental data. To test the theory, we have sent a beam of light towards the sun and it was bent very mildly. To explain how mildly, think of an inch in a mile measuring unit. It was small bend but we have advanced tech to measure it accurately. The bend would increase near black holes or bigger stars. This bend in a light proves that space does bends. 

    One other thing which I didn't know was that scientist defines a position in a four-digit number. First, three-digit numbers tell the latitude, longitude, and height about sea level. The other fourth digit is used to tell the time in space. This four-digit number tells the position in space at a specific time. 

    Hawking indicated that it is next to impossible to travel in the past if the general theory of relativity is correct and energy density is positive. But it is possible to go slow in time if you travel at the speed of light, which is impossible for any rocket. 

    This chapter wasn't really technical. It mostly talks about fiction and hypothetical situations, which I guess is important to understand to grasp the concept of M-theory. 


- **Will we survive on earth?**

    In this chapter, Hawking talks about few dangers that might wipe out humans from the Earth. First, climate change. Climate change is a serious issue that can be dealt with, but it requires strong political will. Polar ice caps have been melting, which reduces the amount of sunlight reflected back in space and this could further raise the Earth's temperature. Second, nuclear war. This is a controversial topic because it usually revolves around politics. Chief scientist Robert Oppenheimer of the Manhattan project, the first-ever atomic project, said later of the first explosion of an atomic bomb two years earlier in July 1945, 

    > We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from the Hindu scripture, the Bhagavad Gita, 'Now, I am become Death, the destroyer of worlds'.

    Since then the doomsday clock has been ticking, In 1947, the clock was originally set at seven to midnight. Some people think it tells the time left for human lives and some people think that it's a waste of time. 

    On a personal note, it is fascinating to think about it because it shows that scientists knew that one day humans will wipe themselves out using their own creation. 

    Third, asteroid hit. Earth has already been hit by an asteroid sixty-six million years ago and we will be hit by another asteroid in future which has been proven by physics and the probability. There is no rigid defense of stopping an asteroid hit and we might have it in the future. 

    The only way to make sure that human mankind continues to live on is by leaving the planet Earth and make another planet our home. People are already working on this idea. Hopefully, we will get to Mars by 2024. 


- **Should we colonize space?**

    The argument between going into space versus improving our planet has been a long-overdue debate between activists and researchers. Both of them are right. Both are necessary. We could solve the issue of climate change, over-population, the spread of diseases, poverty, and other Earth problems while continuing space exploration. Our world's GDP can allow both of them to work together at a great force, but it requires political will, which is a challenging part. Saying no to space exploration is stupidity. Imagine if you are stuck in the desert, would you not try to reach out to the other parts of the Earth? We don't have any more unexplored space left on Earth, and we are depleting Earth's resources to the full extent. This chapter forces readers to think about this issue from its root causes. If we don't find any other place in space for new homes, human mankind will eventually die. 

    Hawking also discusses long-term research that's been happening for humans to travel long distances in space. Researchers have been trying to design an idea of sending Nanocraft at less than a speed of light with light beam technology and send back data with the same beam. We are trying to implement what Einstein used to imagine traveling at the speed of light in reality. 


- **Will Artificial Intelligence Outsmart US?**

    This chapter was terrific because it aligns with my career choice, IT. It has always been an argument about whether AI will take over humans? The answer is not that easy to understand. We are using AI in many sectors of our society. Even when I am writing this sentence, there is an auto-correction tool that is continuously correcting my writing. That is an AI. From the technical standpoint, the ability to make decisions on their own comes from machine learning, where one feeds tons of data to AI to make better decisions. Feed more data and an AI would be more precise. According to Hawking, we can reap the benefits of AI by managing the risks that come with it. Many tech pioneers like Bill Gates and Elon Musk understand the implications of AI on society. Elon Musk has warned that 

    > Superhuman artificial intelligence is capable of providing incalculable benefits, but if deployed incautiously will have an adverse effect on the human race.

    Hawking touched on the topic of military AI robots. The world militaries are considering making AI robots that can decide and kill their targets on their own. The world UN is debating to whether allow this technology or not. Even if we don't deploy such kind of technologies, there is no guarantee whether it will stop countries to make such kind of technology and sell to bad people on the dark web. 

    There could be a lot of negative effects of AI on the human race. Like, an AI could literally crash the stock market and take over e-commerce. An AI could redesign itself and make itself better. They could make weapons by themselves that humans might not be able to ever understand. 

    But, if implemented correctly, an AI could help the human race. Self-driving cars, surgery bots, implants for disabled people, etc. are a couple of the sectors where AI is helping us. Also, don't forget that AI is heavily involved in space exploration and one day it might take us to mars.