'Brief Answers to Big Questions' is Stephen Hawking's last book and despite promises made and almost kept, about no equations, I still found myself frequently in deep weeds of lack of understanding. But after re-reading in some areas the weeds became less thick. You may find yourself with your own “uncertainty principle” .
While I have developed no ability to imagine multiple dimensions beyond the standard three, I was persuaded to add 'time' as a fourth. I also learned that a triangle can have more than a total of 180 degrees in its three inside angles.
Hawking's ideas about black holes have put him into the pantheon of great scientists, of which he regards Albert Einstein as the “most remarkable scientist who ever lived”. In his life,, Hawking had a dimension where he has left even Einstein behind and that is his facility among scientists to be known, respected, even loved by the general public.
His ability to survive ALS into advanced years and thrive in a wheelchair with limited ability to move any muscles and communicating through a mechanical voice, have augmented his reputation. I once read that the most interesting people of the 19th century were Napoleon and Helen Keller. I could imagine Hawking being seen that way for the 20th century.
Endearing him further to the public is the sense of humour of the Cambridge University's Lucasian professor of mathematics. When sympathized that he hadn't won the Nobel Prize in physics, he countered with “but I have been on the 'Simpsons'”. While he enjoyed the limelight, he was at the same time baffled by it.
Dying in 2018, he is interred between Isaac Newton and Charles Darwin.
The book discusses his 10 big questions in a chapter each. They are; 1. Is there a God? 2. How did it all begin? 3. Is there other intelligent life in the universe? 4. Can we predict the future? 5. What is inside a black hole? 6. Is time travel possible? 7. Will we survive on earth? 8. Should we colonize space? 9. Will artificial intelligence outsmart us? and 10. How do we shape the future?
He does all this in a surprisingly short 200 pages.
He describes 'general relativity' as the theory of the very large and 'quantum theory' as the theory of the very small.
He says science is increasingly answering the questions that used to be the province of religion. However, religion still holds sway with many for its comforting aspect and those who neither trust nor understand science. Unlike the laws of man, the laws of science cannot be broken. “My prediction is that we will know the mind of God by the end of this century.”
The universe, he says, is governed by laws which can be understood by the human mind (some minds can). “Discovery of these laws has been humankind's greatest achievement, for it is these laws........ that will tell us whether we need a god to explain the universe at all.”
“The one remaining area that religion can now lay claim to is the origin of the universe, but even here science is making progress and should soon provide a definitive answer to how the universe began.” “Asking if God exists is a valid question for science.”, he says.
Hawking suggests an independence and absoluteness of laws without addressing the idea that we understand the laws because we put them in terms we can understand, so we understand them. We do not necessarily break out of this circle. It will always be in our terms, because we have no others.
Three ingredients are needed to make the universe....matter, energy and space, or two if you see matter and energy, as Einstein did, as the same.
Hawking says God comes back into the picture in the creation of energy and space.
The laws of physics, he says, demands that there be “negative energy”, a difficult idea to grasp.
And another big idea is that time does not exist inside a black hole, nor did it before the 'Big Bang'.
And still another, a thing can come into being and disappear then reappear according to the laws of quantum physics.
Hawking says we know the laws that govern all but the most extreme conditions such as black holes and the origin of the universe. There is no time for a cause or a creator to exist.
Hawking's understanding denies an afterlife.
And tough to get one's head around, and many don't, the general theory of relativity, where Einstein said neither time nor space are absolute, but shaped by matter and energy.
Hawking says that galaxies seem to be spaced uniformly in the universe with each containing billions of stars. One of the great discoveries of the 20th century is that the universe is expanding, contradicting the steady state theory.
Scientists, he explains, are used to seeing an indefinite chain of causes and are uncomfortable with the idea that it leads to a first event.
The 'big bang' postulates that the whole universe was “scrunched into a single point of infinite density” and with this singularity current scientific laws break down. To some degree Werner Heisenberg's 'uncertainty principle' provided some solace for this consternation.
And Hawking explains that things getting more disordered and chaotic with time is the second law of thermodynamics.
At the time of the 'big bang', he says, there would have been equal numbers of neutrons and protons, but with rapid cooling neutrons started to decay into protons. The first substances formed were hydrogen and helium and where there were greater concentrations gravity further increased the concentration leading to the construction of galaxies, he explains.
As heat burned these compounds, other more dense ones like carbon, iron and oxygen were formed. These in turn formed planets and it is now estimated that one in five stars may have a planet like earth, compatible with life.
Hawking fairly quickly gets to DNA and how it carries information used to create and transmit life. He briefly points out that our intrinsic qualities may have changed little since living in caves, what has changed is the accumulation of knowledge in the last 10,000 years, accelerating over the last 300.
Our brains, however, have only evolved on the Darwinian timescale leading to problems that are likely to increase. So individuals, knowing a progressively smaller proportion of the information, must specialize.This seems one of the more important observations in the book.
With our Darwinian evolution not keeping up, humans may design ways to accelerate it by manipulating DNA. Along with this may be further development of machines more durable than humans, particularly for use in space travel, maybe replacing DNA lifeforms.
He suggests that intelligence may not have longterm survival value and compares it with single cell organisms which have their own advantages. While life may exist on other planets “intelligent” life is likely rarer and more likely to be extinguished in catastrophic events, such as killed the dinosaurs.
A burned out star without additional pressures would contract to a point of infinite density, referred to as a “singularity”. At a singularity our physics concepts of space and time break down such that it is the end of space and time....an idea you can try to wrap your head around.
A 'black hole', usually from a collapsed star, has gravity so great that not even light can escape. There is believed to be a black hole four million times the mass of our sun at the centre of our Milky Way galaxy.
The 'event horizon' of a black hole is that last point at which you could theoretically escape. It seems that some radiation or heat is continually emitted by black holes. However, what comes out will bear no resemblance to what went in.
And here it gets complicated ... deep weeds as I suggested ”the antiparticle falling into the black hole can be regarded as a particle coming out of the black hole.”
A mini black hole would be a good source of electricity, however it would be hard to contain one, because of the great density, it would instantly fall to the centre of the earth.
And 'loss of information' that occurs in black holes is “one of the biggest unsolved problems in theoretical physics”. Fortunately it does not keep many of us up at night.
Black holes are characterized by their mass, electric charge and spin outside the event horizon.
'General relativity' is about curved space and warped time, 'Special relativity' relates space and time to each other. A position of something depends on three physical dimensions describing position and time, a fourth.
For time travel the spaceship must exceed the speed of light and the power needed as that speed is approached is approaching infinite. The warping of space seems one possible way of time travel. That warping, says Hawking, “would be a matter of negative mass and negative energy”. I'm back in the weeds.
Classical laws of physics were overthrown by quantum theory which has things happen that don't under “normal” physics. It involves a short credit/debit balance. The negative energy idea, he says, is based on the uncertainty principle.
The conceivable ability to construct a “wormhole” or warp space may allow us to travel into our past. But so far nobody has come back from the future. Warping seems more possible to the future than the past which we have already observed, he adds. And these ideas don't get any easier to understand going forward in the book.
And to further complicate things, M-theory, a unifying of string theory suggests that rather than four dimensions there are 11, the additional seven are in a space “so small we don't notice them”.
Hawking's conclusion is that time travel can't be ruled out.
The physicist points out that the human created problems of rising temperatures, reduction in polar ice caps, deforestation, over-population, disease, war, famine, lack of water and decimation of animal species are all solvable, but so far haven't been. These could make the planet uninhabitable.
We have no defense against an asteroid collision, another singular disaster.
He suggests that by the time the dangers motivate political action it may be too late. He calls for an immediate cut to carbon emissions.
Hawking predicts that a nuclear confrontation or environmental catastrophe will cripple the earth within the next 1,000 years, a blink of the eye in geological time.
The race may survive in that some may have escaped earth by that time. “I think we are acting with reckless indifference to our future on planet Earth.” He says spreading out may be the only thing that saves us from ourselves and the technology is almost within our grasp.
“The present exponential growth cannot continue indefinitely.”
And back to physics. At the beginning of the 20th century our understanding of nature went down to a hundredth of a millimetre, atomic physics in the first 30 years of the century reduced that to a millionth of a millimetre, since then research in nuclear and high energy physics has reduced that by a further factor of a billion as even smaller structures are found. The ultimate theory of everything may rely on mathematics. And this, most of us will not be able to fathom.
He gives a brief biological explanation of the origins of life. The complicated DNA molecule emerged about 3.5 billion years ago. What happens there, is to a large extent governed by four nucleic acids cytosine, guanine, adenine and thymine and the combination of their appearance on the DNA molecule.
n the past, it evolved slowly. We are approaching the point where we can control it (human genetic engineering) and its effects and increase its rate of change. From this will be a new level of social and political problems. And with this, Hawking expects that people will become fundamentally different.
It may mean a kind of race to keep biological systems ahead of electronic ones, which are still not as complex as the brain of an earthworm, he adds.
Hawking does not buy “the science fiction picture of an advanced but constant future” where humans are the same, but the circumstances changed. This scenario is portrayed in the Star Trek series.
The complexity of both humans and machines will increase rapidly, says Hawking.
Moving from earth into space will not alleviate problems on earth, he says, except in that it gets us looking outward rather than in.
While we have visited the moon and a planet of Saturn with technology, looking to the future we have to go ourselves, he advocates. He calls for spending a quarter of one per cent of World GDP for the venture.
The 1972 moon landing motivated people's interest in science and gave humanity a different perspective. A crewed space flight would create enthusiasm for space and increase interest in science. Hawking sees it as essential for humanity to “have a future”.
Rather than working from a space station, the base, he says, should be on a planet or a moon with gravity, resources and surface to dig into for shelter. He suggests that the moon and Mars seem the most suitable. Looking further out, there are about 1,000 stars and an unknown number of planets within 30 light years.
Under current chemical power, maximum speed that could be reached is about half a kilometre per second. Estimates are Mars could be reached in 260 days and as little as 130 days. With that technology the nearest star is three million years away.
Nuclear fusion could boost the speed to a 10th of the speed of light. Beyond that might be matter- antimatter annihilation or a new form of energy to make interstellar travel possible. He doesn't deal with how slow acceleration would have to be for humans to survive.
One exotic, he mentions, is a light powered probe weighing a few grams with a light sail pushed by lasers. This might reach a speed one fifth of light.
His prediction is that within 100 years visiting all but the outer planets in the solar system will be possible and another 400 years for nearby stars and a round trip of 10 years.
And behind solutions, Hawking refers to, is artificial intelligence and he warns that it would be a mistake to underestimate artificial intelligence becoming greater than human. Improvement in AI should also be paired with consciousness of having it aligned with our goals. And then there is the issue of how diverse they might be.
He fears the consequences of another intelligence that can match or surpass humans. Then AI may take off with it own motivations where our own rate of evolution could not compete.
In the medium term, he says, we will see it automate our jobs leading to greater prosperity and equality, but there seem no fundamental limits to the development of AI. This development could be the best or the worst, he adds.
Hawking compares the introduction and evolution of AI with the arrival of an alien civilization, that has given us some notice and time to respond. How will we use it? In these comments, he refers to Bill Gates, Steve Wozniak and Elon Musk as sharing his concerns.
Creating AI that can be controlled is important. There are attempts at giving some levels of AI rights and responsibilities.
Hawking believes we are just at the beginning of the AI revolution and the “future of communication is brain-computer interface whether with electrodes or implants. Under this type of pairing the brain would have all of wikipedia. As it is now we have to go through the laborious process of googling stuff.
Even now people are increasingly connected to information and each other. The acceptable limits, if any, of genetic engineering will become an increasingly urgent question.
Evolution has suggested that intelligence is the ability to adapt to changes. And, says Hawking, we need to make change work to our advantage. And with powerful technologies , he says, we must get things right the first time (wisdom), since there may not be another.
Hawking's reverence for Einstein is embellished in his last chapter. “Where did his ingenious ideas come from? A blend of qualities perhaps:intuition, originality, brilliance. He was undaunted by common sense, the idea that things must be the way they seemed. He had the courage to pursue ideas that seemed absurd to others. (A key element was imagination.) And this set him free to be ingenious, a genius of his time and every other.”
Hawking attributes “a global revolt against experts” in part to Brexit and Trump forces.
“Most people,” says Hawking, respond to qualitative, rather than quantitative understanding, without the need for complicated equations. Only a small percentage of the population read even the most successful books.
For what lies ahead for the young now, Hawking says, “I can say with confidence that their future will depend more on science and technology than any previous generation's has done.” And in the wake of this statement, he recites, the big problems here, or on the horizon, most rely on scientific solutions and widespread novel political courage.
He says the earth is too small for us and the “physical resources are being drained at an alarming rate. Mankind has presented the planet with disastrous gifts of climate change, pollution, rising temperatures, deforestation and decimation of animal species.”
The physicist believes the future of learning and education is the internet and the connectivity of it means something like a “giant brain”.
Whatever young people do, he says, “all should be familiar with and confident around scientific subjects”. On the threshold of scientific discoveries, the world will change enormously in the next fifty years.