Have you ever worried about dark forces infiltrating your phone calls and eavesdropping on your private conversations? Well, astronomers have good news for you: it won’t be aliens with their ears (or the auditory sensory organs they’ve developed) for the speaker that enters your company.
At least not yet. Unless they’ve done much better than we fund radio astronomers. And only if they are Really next to.
SETI – the Search for Extraterrestrial Intelligence – scientists have long pondered how to detect life outside Earth. Assuming there are technologically advanced aliens out there, they might be trying to communicate with us. Or they could just leak radio energy into the cosmos by accident. Anyway, can we pick up this signal?
One way to approach this question is to reverse it: we know how much energy were distribution in space. Given our own level of technology, could we detect such a signal from light years away? If so, then maybe we can hear ET too.
SETI scientists have mainly focused their efforts on radio waves, because they are easy to manufacture – any young technological civilization will figure this out pretty quickly; after all, we did. They can be radiated with great power, contain a great deal of encoded information, and can travel easily through the myriad clouds of dust and gas that litter our local space environment. They are ideal for intergalactic communication.
This kind of study has been done in the past; research published in the journal Science in 1978 examined our television signals and our military radars, the strongest transmissions we had sent into space at the time. Current radio telescopes could detect such emanations up to 25 and 250 light-years away, respectively, a volume of space that encompasses several hundred thousand stars.
Over the decades that followed, our TV broadcast signal dwindled as we turned to cable and the Internet to deliver our shows. Gone are the days of wondering if aliens loved Lucy as much as we do, I’m afraid.
But other methods of communication are on the rise, and they might prove more fruitful for any alien looking for another lonely civilization to chat with. New research by SETI scientists, published in the Royal Astronomical Society Monthly Noticesexamines how our cell phone use might be detectable by other stars.
Without going into too much technical detail – the FCC has a decent page explaining how it works – cell phones emit a weak signal which can be detected by a nearby tower, which in turn emits a much stronger signal to send the transmission . A given telephone company’s coverage is divided into small areas called cells, each populated by one or perhaps a few towers that can pick up nearby telephone signals.
While a personal phone only produces a fraction of a watt of signal strength, a tower puts out a few hundred watts, about the same as a bright light bulb. It’s not a lot, but there are a lot in total. OpenCelliD, an open database of cell locations, has 30 million cells listed worldwide, and while it’s hard to know exactly how many towers that is, there must be at least one per cell. . The total power emitted by them can be measured in gigaWatts, a very strong signal indeed.
What an alien detects when pointing a radio telescope at Earth, however, depends on more than the combined signal strength of all those towers. The direction transmitted by the pylons is also important. Most human cellphone users are located near the Earth’s surface, so the tower’s antennae are configured to send their signals parallel to the ground, covering it like a lawn sprinkler spraying water. If you’re on the ground near the tower, you’ll get a strong signal, but if you’re above it, you’ll only get a weak signal at best.
The location of the towers also matters. The United States has millions of towers, but very few are in the Pacific Ocean. Also, there are more towers in the Northern Hemisphere than in the Southern Hemisphere, so our alien friends would see a different signal depending on where their home star is in the sky.
Putting it all together, scientists modeled what aliens would see from hypothetical planets orbiting three nearby stars: HD 95735, Barnard’s Star, and Alpha Centauri A. All of these are within 8 light years , practically in our galactic backyard, maximizing the spy abilities of any curious aliens. The stars are also widely spread in declination (the measure of latitude on the sky), to see how the Earth appears in different directions.
The conclusion? While the alien technology is the same as ours — with a radio telescope as large as the 100-meter Green Bank Telescope in West Virginia — our overall cellphone signal is still far too weak to detect from one. three stars. The next generation Square Kilometer Array, currently under construction in Australia and South Africa, will be more sensitive, but still only has about 1% of the sensitivity needed to detect transmissions from Earth to tens of trillions of kilometers.
If they look like us, then we’re safe from eavesdropping. On the other hand, judging from my time in airports and other public places, a lot of people don’t care at all who hears their calls. I wouldn’t go so far as to say I hope aliens abduct them, but I’m not. not say that.
What if our galactic neighbors were technologically more advanced? Telescopes detecting interstellar radiation are like buckets placed outside in a downpour: the larger the bucket, the more water it collects. It is technically feasible to build radio telescopes much larger than the ones we have today. There are even serious proposals to build huge radio telescopes on the Moon. These would be much more sensitive than what we have today, perhaps able to pick up such mobile transmissions even at interstellar distances.
So it’s still possible that ET could listen to our cell phones, provided they’re close enough, in the right part of the sky, and have slightly better technology (or tentacle or pseudopod) than ours. Currently.
You can choose which part of that last sentence is the most far-fetched. But anyway that’s a lot of ifs. The longest odds are that they are so close to us; if their home world is a thousand light years away, they would need a telescope the size of a moon to pick up our transmissions. Possible, but a lot of effort.
Yet scientists note that the population of terrestrial cell towers is growing, and we are getting brighter in radio waves every day. They also plan to expand their work to include more powerful 5G towers, radar, satellite services, and more to better understand how much we advertise our presence in the galaxy.
Also remember that this is all about answering the more pertinent question of whether We can hear them. This is still a tentative “maybe”, an ambiguous if somewhat infuriating conclusion. And of course, it all still hinges on the biggest question of all: are they even there?
If so, ET, please call Earth: we look forward to your call.
This is an opinion and analytical article, and the opinions expressed by the author or authors are not necessarily those of American scientist.