I ask you to build tractors, but you build rockets?

[Log time (urgent): 20.21.54 9/5 18

Signal type: Gravitational waves

Code: GW180509 (International common naming standard: GW is the abbreviation of Gravitational wave, 18, 05, and 09 represent the year, month, and day respectively)

Frequency: 32 (Hz)

Detection source: G00

Information volume: Complies with AAAA level warning, dormant state is released, information is sent in D4 mode, transit star: ‘Golden Crow’

Note: It has entered the search state on its own.

...]

When 'Lihuo' sent back the information, it was already 20:24, and only 8 minutes had passed since 'Robin Hood' detonated. Taking into account the one-way delay of more than 3 minutes from Mars to the Earth, as well as the time to process the information, it can be seen that the Discover the connection between the two.

Information is transmitted at the speed of light. Through unknown means, the "unknown" on Mars detected the nuclear explosion on the moon, and then immediately sent out a gravitational wave signal.

It is a medium-wave signal with a transmitting power of no more than 100 kilowatts. It is difficult to detect with a rough detector called Lihuo, but it is so close that it is almost within reach.

So much so that 'Lihuo' could easily determine that the signal was sent from Mars and analyzed it immediately. Although it did not decipher it, it could still judge from the extremely regular waveform changes that this was definitely an intelligent signal, which directly triggered the signal. Top 4A level warning, automatic wake-up to issue an alarm.

The appearance of gravitational waves only lasted for a brief 0.5 seconds, but they were faithfully recorded by Lihuo and sent to the earth.

Although it is theoretically possible for several other gravitational wave observatories to receive information, the base is definitely the one with the fastest response and the most information. It is not even possible to rule out the possibility of being the only one, because it is too difficult to detect gravitational waves.

A big reason why gravitational wave detection is difficult is that it is too difficult to emit high-power gravitational waves. Only the mass of the Earth orbiting the sun can generate about 200 watts of gravitational wave power. Jupiter only has 5,000 watts, and the cycle is calculated in years. , cannot be observed at all.

Therefore, when Einstein predicted gravitational waves, he also believed that humans would never detect gravitational waves because they were too weak.

The first discovery of gravitational waves by humans was GW150914 discovered by LIGO. It was formed by the merger of two black holes with masses of 36 times and 29 times the mass of the sun. The relative speed during the collision exceeded 0.6 times the speed of light, and a single black hole was formed after the merger. The mass is about 62 times the mass of the sun.

That is, matter about three times the mass of the sun is converted into gravitational waves in just one second, and its peak power is 50 times the total external power of all stars in the entire visible universe.

Such powerful gravitational waves only move LIGO's 4-kilometer-long arm by one ten-thousandth of the diameter of a proton, which is equivalent to one-625 trillionth of a human hair.

It is precisely because of this that GW180509 cannot be formed naturally, and Mars cannot generate gravitational waves of such power.

Of course, GW150914 is 6 to 1.8 billion light years away from the earth, and the attenuation of GW180509 is definitely not that exaggerated, so it is possible for the earth to detect it.

But in general... there is a 50-50 chance. Anyway, "Shanhai" has controlled the communications of several observatories and their personnel, and nothing has been discovered yet.

And this is not its main job. Now the Star-3 computer is going all out to try to crack GW180509.

Lu Qun couldn't care less about the shock now and tried to analyze the pattern of GW180509.

Compared with the misunderstanding of the Ami M incident, this is the real alien encryption.

For such a completely unfamiliar encryption, it requires the joint efforts of a group of sociologists, biologists, linguists, etc. Fortunately, the base has previously attracted some talents for the sociology of the universe, and they are on their way.

"No, I can't help it."

Lu Qun put down his pen and shook his head slightly. There was already a sheet of manuscript paper in front of him, filled with various calculation notes.

"I have tried several conventional simple encryptions and most base systems, but they still don't work. I still hope that professionals can get some results, but I think the content transmitted by this gravitational wave should not be complicated."

The gravitational waves, which lasted only 0.5 seconds in total, were indeed very short. If the waveform had not had several obvious complex regular ripples and was emitted from Mars, it would have been difficult to make an absolute conclusion.

"Let's stop Shanhai. We don't even know the encryption method. We won't have the answer for a lifetime with the existing exhaustive methods. It's better to wait for quantum computers to be more reliable.

We know nothing about extraterrestrial civilizations. It is unrealistic to decipher the contents of a signal just by relying on it, unless a particularly large number of signals are received. "

Hearing what he said, all the base executives standing behind them couldn't help but sigh.

Ye Changsi had expected it, and he only found Lu Qun to give it a try.

"It's okay, this is normal... Although we can't crack it, we should at least know why it appears."

GW180509 and the Robin Hood explosion occurred almost simultaneously, and are obviously inseparable.

But if nuclear bombs can trigger gravitational waves, even if they have not been detected before, why did the Tomishima hydrogen bomb in December not trigger it? Lihuo was already on Mars by that time.

Several people quickly looked for breakthrough points and quickly concluded two differences:

The yield of this explosion is 1.55 million tons, which is larger than the previous three times. It may just reach the threshold that triggers the alert;

Location, this is the first time that humans have detonated a nuclear bomb in a place completely far away from the earth and atmosphere. This is also quite special and deserves focused study.

Then there are questions:

Why send gravitational waves? Is it just because of nuclear bombs or for other reasons? On what basis?

How did the Mars ‘transmitter’ detect a nuclear explosion nearly 60 million kilometers away?

Who built the ‘launcher’ and for what purpose?

To whom are gravitational waves sent, and are there aliens in the solar system?

"First of all, the information about the hydrogen bomb explosion is conveyed at the speed of light."

Serev spoke first:

“We can basically conclude that Mars sent information immediately after detecting the explosion of the hydrogen bomb, and the delay in the middle was negligible. This shows that there are long-term active listening stations on Mars, so it can respond immediately.

The second point, in fact, I think what needs to be paid attention to most is why it is the moon, whether it only focuses on the moon or whether it has reactions outside the earth.

The moon must have some kind of special status in this matter, and we happen to have the ability to deeply explore the moon. If possible, I also recommend carrying out several more nuclear tests. Of course, this is very risky. "

"no!"

Xiao Gangtian almost immediately rejected Serev’s last proposal:

"We need to think of the worst in everything. We can no longer continue to stimulate alien civilizations. This is playing with fire.

Think about it, they may have started monitoring a long time ago. If today is the first time it is triggered, it means that certain set conditions must be met. I don't think it will be a good thing for the farmer to come after the sheep are fattened. "

"Think about it, how would you react if you learned that a child had a knife in his hand?"

Xiao Gangtian, who is in charge of deep space exploration, has spent a lot of time studying extraterrestrial civilizations and has frequent contacts with the philosophers and biologists raised at the base. His overall thoughts tend to be extreme.

“We think about everything from the most basic and simple perspective: What can we know from the ‘monitoring station’ on Mars?

Obviously it is unlikely to know that a man named Xiao Okada is talking here, but it must know that humans have a hydrogen bomb, and the information conveyed must also include this.

The hydrogen bomb is like a knife. Although it is not worth mentioning compared to mankind's advanced weapons, it is a threat as long as someone is holding it, and all civilizations must put their own safety first, otherwise why are they here? When to send a signal?

This is a civilization that has mastered gravitational wave communication technology, and it placed a 'monitoring station' here who knows how long ago. What height has it developed to now? "

"Then what should I do? Can I just hide my head in a non-existent turtle shell and wait for death?"

Perhaps because his own experience was so extraordinary, Serev was a little dissatisfied with his pessimism:

"We are not ordinary human beings, and sooner or later this day will come. Now it is just a year or two ahead of schedule.

On the contrary, we should send astronauts to land in advance to find out what is there. It is a real-life gravitational wave communication antenna! "

Seeing that there was something wrong with the atmosphere between the two, Ye Changsi interrupted them in time and returned to the topic:

"How to respond is not the focus. The focus should be what the signal transmits, whether the purpose of monitoring us is good, and the most important point is how far away our civilization is from us, and whether there are other alien civilizations in the universe."

Alien civilizations do exist. This is one thing that GW180509 absolutely confirms. So it stands to reason that there is more than one alien civilization.

Gravitational waves are transmitted at the speed of light and will spread throughout the universe without any dead ends. This is equivalent to a cosmic-level broadcast.

Judging from mankind's current observations of surrounding galaxies, no traces of civilizational activity have been found within at least hundreds of light years, and no communication signals have been detected.

It can be seen at a glance that GW180509 is regular. It has not been disguised at all. Even the signals sent secretly by 'Lihuo' are disguised as natural signals. So why is GW180509 so bold?

Isn't it worried that the signal will reveal its existence, so it uses it unscrupulously?

And from a communication perspective, neutrino communication that can be directionally emitted, have strong penetrating power and high information density is more in line with non-superlight interstellar communication methods.

Of course, no matter what, the issue that humans need to worry about most is where the receiving end is.

Since it is transmitted at the speed of light, even if the signal flies out of the solar system, it will take one year, and it will take four years to fly to the nearest Alpha Centauri galaxy. It will take 20 years to fly to some promising planets further away, such as Glazer 581, and even further away. It's hundreds and thousands of years.

The Orion spiral arm where the solar system is located is very remote, and the places where alien civilizations may live are just too far away.

If an alien civilization prepares to destroy the earth and organizes a light-speed fleet to set off after receiving the signal, it is likely that hundreds of years will have passed by the time it arrives. Humanity may have a technological explosion and be able to fight against it. Even if it doesn't work, it can escape to the interstellar space and seek revenge.

As for faster-than-light travel, we can ignore it. A civilization that has not even mastered delay-free communication cannot have the technology to achieve faster-than-light travel.

So if the alien crisis doesn't arrive until tens or hundreds of years later, with the base's development speed, it might be able to whip the little green men in turn.

On the other hand, if the receiving end is not tens or hundreds of light years away, and there happens to be a huge alien fleet flying silently just a few light years away, it will fly over immediately after receiving the message.

Although this may be so small that it is almost non-existent, but even aliens have appeared, what else can you absolutely not believe?

How to treat aliens and how long a safe time is to be determined will directly determine the base's response strategy.

"At least 20 light years, right?"

After listening to the problem described by Ye Changsi, Serev thought about it and answered:

“I don’t know much about extraterrestrial galaxies, but at least there should be no alien civilization activities in the star systems within 20 light years, otherwise the super telescope will definitely find something.

The other thing is that they chose gravitational wave communication, which is characterized by small attenuation and wide diffusion, which shows that the receiving end is still relatively far away, otherwise there should be a better way.

One round trip would mean at least thirty years of peace. If there was a station very close by that could interfere with the solar system, at least there would be some traces of it, right? "

"That's not necessarily true. Who said they have to organize a huge fleet from a distant home star or military fortress?"

Xiao Gangtian denied again:

"You may not have read "The Three-Body Problem". It is a science fiction novel of the new century. There is a concept in it that I think is worth learning: weakness is not the original sin of survival, but arrogance is.

Maybe they just need to place an antimatter cannon in a deserted place and activate it to launch an antimatter bomb. Not to mention humans, the sun will be buried with us.

As for things like interstellar fleets, maybe a real cosmic civilization doesn't need them at all. "

Xiao Gangtian's words hinted that Serev was an antique from the last century, but after realizing that Ye Changsi was also from the same generation, he was much more cryptic.

After they finished speaking, a voice sounded:

"Maybe there is a breakthrough."

Yang Zhongkai didn't know when he appeared here. He had just gotten off the plane, and his clothes were all in a mess.

He began to systematically study extraterrestrial civilizations half a year ago, but he soon reached a dead end, and any further progress would be basically a fantasy.

GW180509 shocked him greatly, but he was even more excited.

Hearing his voice, everyone stopped and looked at him.

"There is another place, Titan, Titan must be valuable!

The known alien relics in the solar system are not only Mars, but also there. How small is the chance that a solar system will be visited by two alien civilizations at the same time? Almost zero!

Even if there is, there must be a great connection between these two places. One Mars may not be able to find the answer, but the two places can prove each other. Besides, we have not been to either one.

It won't take a few years to explore them. No matter how urgent it is, I'm afraid we still have this little time, right? "

He cast his burning eyes on Ye Changsi again:

"President Ye, technically no one can replace you, but these things require the brains of sociologists and philosophers."