Hawking has passed away, and as a world-famous physicist and cosmologist , he left behind many important research results during his lifetime, such as Hawking radiation (yet to be confirmed by observation). At the same time, he also left world-renowned popular science works, such as "A Brief History of Time".
Although Hawking suffered from frostbite disease during his lifetime, although he was shackled to a wheelchair for most of his life, and in his later years he could only move a few fingers, lost the ability to speak, and could only communicate with people through a special computer, but he has always been concerned about the future of humanity and the earth, and constantly raised his cry.
Hawking once gave 4 major scientific predictions about the future, each of which is related to the survival and development of human beings, the first is becoming a reality, and will the other three eventually come true?
First, climate change
Hawking believes that climate change caused by global warming will pose a huge threat to human survival. If humans do not control carbon dioxide emissions and allow the greenhouse effect to continue to increase, the final Earth will become like Venus, with a surface temperature of more than 100 °C. At that point, the liquid water will be evaporated, and life will not be able to survive on Earth.
The world is currently experiencing warming, and the temperature is now 1 °C higher than before human industrialization, resulting in a large melting of polar and mountain glaciers. More water in the oceans, and warmer temperatures can also swell the seawaters, causing global sea levels to rise by about 20 centimeters, about a third of which have occurred in the past 25 years.
Rising sea levels will directly threaten the survival of humans in coastal areas, and some islands will even be completely submerged by the sea. In addition, global warming will cause frequent climate extremes, hotter summers, colder winters, extreme flooding in some places, and extreme drought in others.
Second, leave the earth
Humans began on Earth, but should not be bound to Earth. Especially considering the climate change on Earth, asteroids hitting the earth, these events will make the earth's ecosystem unrecognizable, and a large number of species will go extinct, which has happened 5 times in the past hundreds of millions of years.
Although the Earth's ecosystem recovers after each mass extinction event, humanity cannot afford such a catastrophe. Hawking believes that we should focus on the continuation of human civilization, develop higher aerospace technology as soon as possible, leave the earth, and find other habitable alien worlds. The universe is so big, I believe that there will be some planets with Earth-like environments.
Third, artificial intelligence
In recent years, artificial intelligence has developed vigorously and has been widely used in many fields, such as machine vision, automatic planning, and retinal recognition. However, Hawking expressed concern about the rapid development of artificial intelligence, believing that they may threaten humanity in the future.
Artificial intelligence may develop much faster than humans think, and they may be able to accelerate their self-development and achieve self-"evolution" to evolve into a new life form. If artificial intelligence becomes self-aware and frees itself from human control, our relationship with them may be reversed, and human civilization will face a huge crisis.
Fourth, alien civilizations
In the Milky Way, there are more than 100 billion exoplanets. If there are so many planets, there will always be some that will evolve life and even civilization like Earth. Astronomers estimate that there are at least dozens, possibly thousands, of alien civilizations in the galaxy.
At present, humans are receiving radio waves in the universe through radio telescopes, trying to find signals from alien civilizations. Previously, on four probes flying into interstellar space, scientists revealed various information about humans and Earth. Not only that, but astronomers also edit information into radio waves and send them to star systems that may have alien civilizations.
But Hawking pointed out that active contact with aliens could put human civilization at risk. If alien civilizations can cross the vast space to visit the earth, their civilization level will be much higher than that of humans, and the earth may become their target of predation, similar events have happened many times in human history.