Brief Answers To The Big Questions-Part 2

Is Time Travel Possible?

In 1905, Albert Einstein came up with The Special Theory of Relativity. It is a beautiful explanation of a fixed speed of causation. Before Einstein, people believed that time was the same for all observers regardless of their motion. Newton assumed, in his equations, that time was absolute and no one questioned it until Einstein.

There are two postulates in Einstien's Special Relativity. 1) Laws of physics are the same in all the inertial frames of reference. An inertial frame of reference is a region of space that is at rest or moving at a constant velocity. 2) Speed of light (in a vacuum) is the same for all observers regardless of their speed. This is hard to accept because, in daily life, the speed of objects is relative. For example, the speed of a bus would be different for a person standing on the sidewalk and a person cycling on the sidewalk. This is not true for light. Light speed is the same for all observers no matter their speed.

Velocity is equal to distance/time. Since the speed of light has to be constant, the distance and time change as we approach light speed. These effects are called time dilation and length contraction. Time seems to dilate or move slowly when an object moves at an extremely high velocity, and Length seems to contract. This is unintuitive, but that is only because the speeds we encounter, in our daily lives, are so small that amount of time dilation and length contraction that happens is extremely insignificant.

This theory permits time to travel to the future. If you were to accelerate and reach a significant fraction of the speed of light, then decelerate and come back to Earth, a lot more time will have passed at Earth than in your reference frame. You will technically have traveled to the future. From my personal understanding, time travel to the past should not be possible. Time should come to a stop if you travel at the speed of light. But nothing can be accelerated to light speed, it would take infinite energy. Theoretically, there is no way to make time go back. The best we get to work with is to slow time down significantly.

Will We Survive on Earth?

Stephen Hawking was not optimistic that we can survive on Earth in the long term. The more immediate dangers that he talked about are the ones that we will cause to ourselves. Nuclear war can cripple life on Earth, climate change can lead to the runaway greenhouse effect. This is what happened on Venus. The atmosphere of Venus is almost completely made of carbon dioxide. It traps all the heat that comes from the sun resulting in ridiculously high temperatures.

I am more optimistic and have faith in human beings, despite what is going on in the world. At least for the issues like these that are in our control. We must find a way to survive and make the world a better place for future generations than it was for us.

Sooner or later, we will have to branch to other planets (or moons) though. The Sun is in its main sequence right now, which means that it is fusing hydrogen into helium. Once it runs out, it will expand far beyond 1AU (the distance between Sun and Earth). This is the red giant phase of The Sun. It will consume the Earth. This is going to happen, roughly speaking, in the next 5 billion years. We have plenty of time before to terraform worlds in the outer solar system and beyond.

Should we colonize space?

We cannot survive on Earth forever. There are too many things that can go wrong. Even if we managed to survive for the next 5 billion years on this planet, the Sun will expand and consume it one day. We are making significant efforts to go to Mars right now, and it looks like it will happen soon. The gravity of Mars is significantly lower than that of Earth. It can cause problems to the human colonists there. The real challenge would be to have civilization survive on Mars without any help from Earth. That is when we will truly become a two-planet civilization.

Apart from Mars, there are other worlds that we can terraform. Venus would have been perfect for this if it weren't so hot. It is almost the same size as Earth, which means it has similar gravity. It should be possible to terraform Venus (maybe for more advanced humans of the future). We can start with making cloud cities on Venus (a very popular idea in sci-fi). Who knows maybe a thousand years from now we will have another Earth-like planet in Venus.

Apart from our two nearest neighbors, we have plenty of moons that we can potentially go to. Europa of Jupiter and Enceladus of Saturn have captured the interest of the scientific community because of the potential presence of oceans under their surface. As we move out to the gas giants (Jupiter, Saturn) and ice giants (Uranus, Neptune), we have to look at their moons as potential worlds to colonize.

Will Artificial Intelligence surpass us?

I think this is a really complicated question. Artificial intelligence will certainly surpass us in various aspects. Computers are ridiculously good at remembering because they can just store the information and they do not have to forget it ever. All the data stored will be available at any time. This can make them super good at learning and making logical decisions.

AI systems are already beating the best human players at various games. A popular example is when Google's AI beat the best human player at Go. One of the reasons is that the evolution of our intelligence is based on biology and nature, which makes it slow. AI will not have the same issue. The speed of growth for AI systems would be exponentially higher because they are not bound by biology.

Personally, I question whether AI can develop emotions like us. I have not read much on this, but I like to think that consciousness is a fundamental quality of human beings. Maybe my religious upbringing plays a role in this opinion. I don't believe that consciousness is emergent from "computing power." I could be totally wrong though.

People like Elon Musk and Stephen Hawking himself have expressed concerns about a future where AI can super intelligent. It may decide that the best course of action for it is to terminate humans (or put us in the matrix). This is known as the technological singularity. When the AI system progresses recursively; they are able to become smarter without human interaction. We cannot predict what will happen in the singularity. Let's hope the future is bright :)