Due to climate change, overpopulation and falling asteroids, we need to find a new planet. Stephen Hawking is a very famous figure in the scientific world, but do his doomsday predictions make sense? We asked a number of Danish scientists about this.
Stephen Hawking is probably the largest living scientist of authority. He made a breakthrough with his work on black holes and thermodynamics in the 1980s and is consistently cited as one of the world's leading theoretical physicists. Therefore, it is natural that the 75-year-old British professor of mathematics appears more often than others on TV screens and arouses great interest of viewers with his statements.
Recently, especially after the election of Donald Trump as the American president and his subsequent decision to withdraw from the Paris Climate Treaty, Hawking has become especially frequent with his warnings about the death of humanity.
Time to load the spaceship
Hawking recently made a splash with his talk at the Starmus Science Festival in Trondheim in June 2017: “The earth is under pressure in so many areas that it is very difficult for me to be positive. The threats are too many and too great,”he warned, according to Express, as he talked about how we should tackle insurmountable challenges.
“This is not a utopia, our living space is shrinking, and the only places we can run to are other worlds,” Hawking said.
In other words, we humans should already be loading the spaceship and looking for a new planet. And all this should not happen in 1000 or 200 years, as Hawking was previously quoted, but in 100 years. This is the conclusion of his speech.
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These statements naturally began to spread rapidly. But why, in fact, in 100 years should we emigrate from the Earth? What threats will we face?
250 degrees and acid rain
Hawking lists a number of challenges that might be termed time bombs placed under humanity. We are looking at three of them here.
The first and often repeated threat is the undeniably climatic and environmental threat. However, Hawking made some slightly harsher conclusions than we are used to.
“We are approaching the point of no return, when there will be no way to get away from global warming. Trump's actions (the decision to withdraw from the Paris Treaty - ed.) Can push the Earth's climate to the brink when it becomes the same as on Venus, with a temperature of 250 degrees and acid rain, Hawking said in the program. which the BBC News channel prepared in connection with the 75th anniversary of the professor.
If the outlook is 250 degrees and acid rain, then leaving the planet could be quite realistic.
But this prediction is far from reality, according to Jens Olaf Pepke Pedersen, senior researcher at the Technical University of Denmark and scientist who achieved the best scientific result in Denmark in 2016 for research on the effects of CO2 on rising temperatures.
“The same situation on Earth as on Venus, where the surface temperature is about 450 degrees, is absolutely impossible,” he wrote in an email sent to Videnskab.dk.
“Venus is an example of a planet where there may have been a greenhouse effect out of control. This has been happening for a very long time, presumably many hundreds of millions of years. However, there is no indication that the greenhouse effect could spiral out of control on Earth, even under extreme scenarios. There are many stabilizing factors that can prevent the emergence of our climate with extremely high temperatures, so this is an absolutely unrealistic scenario."
In addition, he stresses that the Earth is historically colder than it has been for a long time: “We live in an unusually cold climate compared to other periods of the Earth's climatic history. If we go back 55 million years ago, then the temperature in the Eocene period was at least 10 degrees higher than today, and this did not matter much for nature."
Therefore, the idea of leaving the Earth, according to Jens Pedersen, is also “completely untenable”: “Climate change therefore does not represent an existential threat, under the influence of which we should think about leaving our planet and that the Earth will far from the most attractive planet in the solar system. So the idea of leaving here, in my opinion, is absolutely untenable."
11 billion people
Another threat, Hawking said, is the continued population growth. Back in 2010, Hawking warned of an overpopulation of the planet, and since then the world's population has increased by half a billion inhabitants.
“If this growth continues, there will be 11 billion people on Earth by 2100. Air pollution has increased over the past six years. More than 80% of urban dwellers live in conditions characterized by highly polluted air,”Hawking said recently in an interview with American TV presenter Larry King in 2016.
Thus, the main point here is that we have come to the end point. But this is a too hasty conclusion, says Ole Hertel, a scientist and professor of ecology at the University of Aarhus, who studies the effects of air pollution on humans. He says: “I don't think you can use air pollution as a justification for leaving Earth. Air pollution and climate are driving forces to create a society that is not based on fossil fuels as soon as possible. The shift to a non-fossil fuel society is at the same time a shift to cities with significantly better air quality."
Therefore, we can certainly save ourselves from dangerous volumes of air pollution if we switch to green energy instead of moving to another planet, says Ole Gertel: “Air pollution has increased many times, in particular in Asia, Africa and South America, while it is decreasing in most European cities. But pollution has recently begun to decline as a consequence of the growing shift to green energy. And this is even in a city like Beijing and also in connection with the transition to green energy."
Star explosions, black holes and menacing asteroids
As for Hawking's third and final doomsday prediction that we want to address here, there is little we humans can do here.
Threat from the universe.
As Hawking put it at the Starmus Science Festival, "the universe is a place of violence."
Explosions of stars, black holes and asteroids are a danger that we cannot avoid, he says and warns: “Such phenomena make space travel not very attractive, but it is because of such phenomena that we must study the universe in order to survive, because if we will wait too long, these phenomena will hit us here on Earth. This is not science fiction. The laws of physics and probability ensure that if we stay (here on Earth, ed.), We risk being destroyed."
The earth in the future must inevitably survive the chaos of the universe. Therefore, space travel is our way out, Hawking said.
We invited Ole J. Knudsen, an astronomer and former head of the Steno Museum Planetarium at Aarhus University, to comment on the professor's statement.
“If we believe that we should be saved for a long time, and not, for example, ordinary silverfish, rats or cockroaches, then this (space travel, ed.) Is the only answer, it is absolutely inevitable, because we will certainly fall under the influence of all these phenomena in the (un) predictable future. The Earth will be severely damaged, life will disappear and eventually planet Earth will be destroyed,”writes Ole Knudsen in an email to Videnskab.dk.
"The trouble is, in many cases we don't know when this will happen."
There are many cases of asteroids hitting the Earth. The last time, that is, on February 15, 2013 over Chelyabinsk, it was a lump 17 meters long and weighing 10 thousand tons. And on June 30, 1908, an area the size of Funen (the third largest island in Denmark, translator's note) was destroyed in Siberia. In both cases, we are talking about relatively small asteroids.
But a kilometer long asteroid would lead to continental destruction of life and climate if it collides with Earth, as happened 65 million years ago. But so far, there are no signs of an asteroid on the horizon that would look menacing in the next 50 years, Ole Knudsen said.
“We only know for sure that it will happen again several times, because it has already happened five or seven times in history,” he says.
So Hawking is right that we cannot escape the laws of physics and the universe. However, we do not know when this will happen.
If Hawking is right
Let's assume for a moment that Hawking is virtually correct in all of his statements, and that our only chance of survival is colonizing another planet for the next 100 years. How realistic would such a mission be in this case?
We asked Ib Lundgaard Rasmussen, senior advisor, lecturer at the Danish Technical University and astrophysicist, to comment on this.
“I can assume that we should go to some planet in another solar system. This is due to the fact that for the establishment of a colony in another place in our solar system, there must be the same good conditions as on Earth,”he says.
We accept this assumption. If you want to know if the colonization of Mars is so real that it is also one of the most likely possibilities, you can read our article, where we consider Elon Musk's plans to colonize the Red Planet.
Let's go back to Ib Rasmussen.
“The problem is whether we can gain a foothold on another planet within a hundred years. In addition, the problem is whether we can find the means to carry out such an operation. Let's assume that we can reach a speed of 10% of the speed of light, this is the maximum limit of the fundamental radiation. Thus, in order to reach the planet, which is five light years away, we will need 50 years. Therefore, we can only hope that the planet that was discovered at Proxima Centauri b is an acceptable possibility,”he says.
Proxima Centauri b is the exoplanet most similar to Earth. Let's continue our calculations.
“It is entirely possible to send a research expedition before starting the migration. Suppose the trip takes 50 years, then it takes five years to study the conditions on this planet, five years for the message to arrive on Earth, and then 50 years for the next trip. It takes, as we can see, a lot of time. In order for us to have a real opportunity to find a suitable planet, we need 20 light years. So we need 500 years to colonize another planet."
So 100 years is an ambitious goal, at least if we want to fly to another solar system. What about the economy?
“Here we must take into account that if we are going to make a big space trip, then the price should go down, but there are some physical boundaries that cannot be overcome. It is necessary to use a minimum of energy to start from Earth and go into orbit. The appropriate energy is needed to land on another planet. Then energy is needed to transport the cargo. You can make calculations based on the cost of energy, that is, how much it costs to deliver one kilogram of cargo to another planet. Then, how many kilograms will be the delivery of live weight. Therefore, it is not surprising that space travel is expensive. And this limits the number of people who in reality can be sent to another planet,”concludes Ib Rasmussen.
Unless we find a cheaper way to travel the universe someday in the future. Therefore, we can only hope that Stephen Hawking's doomsday predictions until this moment will not become reality.
Frederik Guy Hoff Sonne