Hawking fears that if we manage to establish contact with extraterrestrial beings, they may react with aggression. However, it is now too late to worry about it.
Physicist Stephen Hawking is sure that space is inhabited by intelligent extraterrestrial beings, and his point of view is shared by many scientists. However, if at first his thoughts were centered around their existence, now he is much more concerned about their behavior. Perhaps alien beings are dangerous.
In a short online documentary, Hawking points out the potential danger of signaling other star systems. After all, we don't know anything about who can inhabit space, and these creatures may well turn out to be aggressive. If aliens detect us thanks to the signals we send, they may send their interstellar artillery at us and take over our planet.
According to Hawking, extraterrestrial civilizations may be much more advanced in comparison with us, ahead of us by many billions of years. It is possible that they will not have any sympathy for us, and for them we will be no more valuable than ordinary bacteria to us.
Aside from the value of bacteria, which is actually quite significant, Hawking is right: we know nothing about the intentions of hypothetical aliens. Perhaps they live in a utopian paradise that humanity has always dreamed of - in a place where peace and quiet are valued. But we cannot be sure of this. In any Darwinian system, aggressive individuals and species take precedence over others. Therefore Hawking's warning is entirely justified. Who wants to go down in history as the person who provoked the destruction of the Earth in a frivolous attempt to start an interspecies dialogue?
Hawking argues that at some point in the future we will receive signals from extraterrestrial civilizations. This is the main goal of the Search for Extraterrestrial Intelligence (SETI) research project, where I am the chief astronomer: we use giant radio antennas in an attempt to detect signals from extraterrestrial civilizations. If SETI experts manage to detect such a signal, many will want to immediately send a response to it - something like: "We are Earthlings, we want to establish contact with you."
Hawking is worried about this kind of response signal that will allow the aliens to know about our existence and whereabouts. He advises to hide. However, it is already too late.
Since the end of World War II, we have broadcast television signals, high-frequency radio signals and radar signals into space. Of course, this is not done in order to attract the attention of aliens - we are talking about the inevitable leakage of radio signals into space.
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At a distance of several light years, these signals will obviously be extremely weak, and in order to capture them, aliens will need antennas many times stronger than ours. However, the difficulties that aliens will face in trying to capture our signals pale in comparison with the difficulties associated with the delivery of weapons to our planet. Let me remind you that our fastest rockets, as impressive as they are, will take 80,000 years to reach the nearest star. Aggressive aliens will obviously need much better equipment. Interplanetary travel - not to mention wars - only seems like an easy task in films.
These simple arguments lead to a simple conclusion. Any alien civilization capable of threatening Earth most likely already has the necessary equipment to detect the radio signals that we have been broadcasting into space for several decades. The radio technology required for this is much simpler than the rocket technology required to travel through space.
And, since we have long been filling the cosmos with our messages that allow us to detect our existence and whereabouts, it is now rather foolish to worry about new such signals.
So, should we worry about future signals being deliberately sent into space? NASA is obviously not worried: in 2008, the agency broadcast a Beatles song in the direction of the North Star. It will take four centuries for this signal to reach its destination.
The space agency doesn't seem to be concerned that this bit of pop culture could force aliens to destroy our planet. Yes, anything is possible. But this does not mean that everything is plausible. Undoubtedly, the Martians could attack Earth in the near future. But this thought cannot deprive me of sleep at night. And it shouldn't bother you.
If Hawking is really that worried about this, then maybe he should make sure his documentary doesn't go into space.
