Of course, in the past 60 years, people have paid little attention to its impact on the universe. Our planet has been exposed to distant stars through radio and television signals. However, some famous scientists, such as Stephen Hawking, have publicly expressed their worries about our existence in other civilizations. These concerns mainly stem from the dark period in the history of our planet, during which more advanced civilizations will conquer and replace less advanced civilizations.
It may be too late for us to hide now, but not necessarily for an intelligent alien civilization. Residents on distant planets may not even like to touch humans like us. Recently, I published a paper with my graduate student Alex Teachey * *, in which I proposed ways to hide planets and discover the existence of alien civilizations. Although we didn't manipulate our signals in this way, it doesn't mean that we didn't do anything for other planets. When we observe the universe to find other habitable planets, we may see processed signals, the purpose of which is to hide or highlight the existence of other civilizations.
When the planet passes between us and its star, the star's light will weaken.
Track the transit to find other planets
Before we discuss how to hide planets from distant peepers, let's consider the best way to find other planets.
Transit method is the most successful technology for human beings to explore other planets. When the planet moves in front of the sun, there will be a transit phenomenon, which will block the sunlight for several hours. So if we look at a part of the universe with a telescope and find that a star disappears gradually at some time in the day, it tells us that another planet is spinning around itself and has temporarily come between this star and us.
By July of 20 15, Kepler had confirmed 4696 candidate planets.
Through this technology, NASA's Kepler program has discovered thousands of planets. Any advanced civilization seems to know this simple method. Every time a planet passes its star, the transit phenomenon must exist at all points on the plane of the planet and the star. An advanced civilization may be happy to tell the whole universe the location, size and even atmospheric chemistry of its planets, but it may also want to hide its existence. If it is the latter, it may choose to build an invisible cover.
Planetary invisibility
Facts have proved that hiding planets by transit method is surprisingly simple, so simple that we can do it now if we want. Because the transit phenomenon is characterized by the weakening of the brightness of distant stars, the invisible cover we imagine will increase the brightness instead.
Laser can effectively compensate for the decrease of brightness. The laser power is all concentrated in a relatively narrow beam, which is just the opposite of the situation that the starlight diverges in all directions. Because of the diffusion mode of light propagation, that is, diffraction, the laser beam will travel around the whole solar system after several light years in space, thus covering the distant planetary system in the beam. When there is no obvious difference in brightness, it looks as if there are no planets at all.
In order to make the laser coverage enough to hide the earth in a similar "Kepler Project" of NASA on other planets, it needs a peak power of up to 30 MW, which is about the electric power output of ten wind turbines.
Kepler can only see one color of light, and advanced civilizations may use more complex detectors to collect all bands of light. Similarly, at present, we can use tunable lasers to hide us, which consumes about ten times as much power as ours. More advanced civilizations may be able to capture other details of this light show and expose the hidden cover. But also, we have no reason not to believe that with a little more effort, we can find a way to build a nearly perfect hidden bunker to find distant stars.
Why hide it?
Yes, it sounds like science fiction, but now only modern technology can hide the signs of the transit of the earth well.
But let's put aside the topic of the earth for the time being. In fact, we have never considered what we should or should not do in this matter from a humanitarian point of view. Conversely, we just assume that if our technology can build such an effective transit cover at a relatively low economic cost, then more advanced civilization may be hidden from us by various detection technologies. The universe may or may not be what it seems.
Why can civilization wrap itself up and not be seen? This may be an insurance strategy: wear a protective cover when looking for nearby planets suitable for life-in case a civilized nation suddenly appears. Such a strategy can reserve enough time for them to appear at the right time.
Given that such a hidden coverage will be so cheap, it is not as strange as it looks. Implement an insurance strategy for your planet. We have reason to believe that an alien civilization may be waiting for the right time-they will supervise the neighboring planets for a period of time before sending out the intergalactic welcome signal. But correspondingly, this technology can also turn the invisibility cloak into a signal that "we are here".
When we see a traffic signal, we think we know what it means. ...
Instead: open the hidden lid.
Maybe not all civilizations are exclusive-some may be eager to communicate. What would you do if you wanted to tell other civilizations that you existed as cheaply and clearly as possible?
Imagine that we see some data of distant planets-this is the daily work of astronomers and notice some strange phenomena. The signal of this planet has a strange shape-in fact, it can't be explained by any of your models. It's like someone put a tag on these raw data. You can't do this in nature-you have detected the signal of another civilization. Another purpose of hiding the laser covering the system is to make the signals of the planets look very unnatural. In this way, their purpose is no longer to create a perfect cover, but to be discovered.
Can such a signal be hidden in our existing measurements? Maybe. No one has observed it yet, and we hope that our work will focus on this frontier field. This may be a protracted war, because in order to do this, we need to try to guess how aliens think, but given the existing science awards, these are all worthwhile. If we find a strange transit phenomenon, it probably contains information encoded by laser pulses. There may be a lot of information hidden in transit signals of other planets.
For us, this is a thirst for knowledge. We only calculated the energy needed to build a hidden bunker or publicize the existence of planets. Whether we should wrap the earth in an invisible protective cover, or on the contrary, we should publicize our existence through laser manipulation. These are all things we have to decide together.
The original text is from Scientific American.
Translation: Rong youying? Summary: kelp silk
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