How to hide Earth from ET? Massive lasers

April 1, 2016 by Mariëtte Le Roux
A view of the Gulf of Mexico and US Gulf Coast at sunset from the International Space Station taken by Expedition 42 Flight Engi
A view of the Gulf of Mexico and US Gulf Coast at sunset from the International Space Station taken by Expedition 42 Flight Engineer Terry W. Virts, in a NASA photo obtained December 17, 2014

The fate of humanity if aliens were to discover Earth with its balmy climate and bountiful resources, has long been a concern for scientists—many of whom fear the worst.

Physicist Stephen Hawking is among those to have warned that ET and his friends may be much more intelligent than us, and may view human beings as little more than troublesome bugs.

Now a pair of astronomers from Columbia University in New York have proposed an innovative method to hide our planet from prying extraterrestrial eyes—using massive lasers.

And it's not a joke, they say.

Alien scientists, argued David Kipping and Alex Teachey, may be trying to find habitable planets using the same technique we do—searching for a slight dip in light when a planet "transits" between the star it orbits and the telescopes watching it.

Planets do not emit their own light and, if they were visible to the naked eye, would appear as dark dots tracking across their bright stars.

But these exoplanets are too far away to see, and all our telescopes can pick up is a small decrease in the starlight emitted during transit.

If aliens spot us using this technique, Earth would be a logical target for alien settlement.

It orbits within the so-called "habitable zone"—not too close nor too far from the Sun—where the temperature is right for liquid water, the essence of life.

Physicist Stephen Hawking is among those to have warned that ET and his friends may be much more intelligent than us, and may vi
Physicist Stephen Hawking is among those to have warned that ET and his friends may be much more intelligent than us, and may view human beings as little more than troublesome bugs

In a paper published Thursday in the Monthly Notices of the Royal Astronomical Society (RAS) in London, Kipping and Teachey said Earth's Sun transits could be masked by shining huge lasers to cover the dip in light.

Strange but true

"Despite the timing, it's really not an April Fool's joke," RAS deputy executive director Robert Massey assured AFP on Friday.

"This is a serious piece of work."

Humanity's search for a planet capable of hosting life remains an academic pursuit—there is no solar system near enough to reach without time travel.

Workers check the Kepler space telescope at the Hazardous Processing Facility at Astrotech in Titusville, Florida, on February 13, 2009, in an image released by NASA

Since its launch in 2009, NASA's Kepler exoplanet-hunting space telescope has found thousands of candidates.

Astronomers have verified the existence of nearly 2,000 faraway worlds, but most of those orbiting in habitable zones have been gas giants.

"The transit method is presently the most successful planet discovery and characterisation tool at our disposal," wrote the duo.

"Other advanced civilisations would surely be aware of this technique..."

Within the wavelength spectrum of visible light, the transit signal could be masked with a monochromatic laser emitting about 30 million watts (MW) for 10 hours at a time, once a year.

One MW can power several hundred homes for an hour.

A universal cloak effective at all wavelengths, would require a much larger array of lasers with a total output of 250 MW, said the team.

"There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilisations potentially living on planets elsewhere in the Galaxy," Kipping said in a statement.

"Our work offers humanity a choice, at least for transit events, and we should think about what we want to do."

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18 comments

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spteso
3.3 / 5 (3) Apr 01, 2016
"Humanity's search for a planet capable of hosting life remains an academic pursuit—there is no solar system near enough to reach without time travel." --- say what?
antialias_physorg
4.4 / 5 (7) Apr 01, 2016
"There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilisations

a) If they are more advanced than us they know we are here (or could see through any 'primitive' cloaking attempt by us, because they will have methods we haven't even though of - and hence cannot 'defend' against)
b) If they are less advanced then they are not a problem

Either way I see no benefit in any effort at cloaking.

Certainly don't think we should advertise our position for the same reasons. if a) then it's not needed. If b) then there's no point.
Eikka
3 / 5 (2) Apr 01, 2016
Yes, it is an april fool's joke.

For starters, the lasers would have to be on all the time because we don't know where the aliens are coming from. Secondly, to fill in Earth's shadow using lasers, you'd need hundreds of terawatts.

The clue:
One MW can power several hundred homes for an hour.


Such a gross factual error can't be a honest mistake.
scialot
5 / 5 (1) Apr 01, 2016
A similar idea was used in Larry Niven and Jerry Pournelle's "Mote in God's Eye", 1976.
petersonwalter
3 / 5 (2) Apr 01, 2016
If the aliens are as smart as Hawkins believes, they probably know about us already. We need to find out who, what and where they are in order to consider a rational response to contact.
Gigel
2 / 5 (2) Apr 01, 2016

a) If they are more advanced than us they know we are here (or could see through any 'primitive' cloaking attempt by us, because they will have methods we haven't even though of - and hence cannot 'defend' against)

The primitive cloaking will tell them there are some sort of primitive weirdos there who are waiving the hand in an attempt to confuse outsiders, so they won't send a survey ship, they'll send a full military fleet. Nice try, humans!
x24val
3 / 5 (1) Apr 02, 2016
Hide!? If anything given a lot of factors, I want Us/Earth to send out a distress signal...an S.O.S.

Perhaps there's some truth to the "nature preserve hypothesis" for the silence so far.
Thorium Boy
4 / 5 (1) Apr 02, 2016
No matter how advanced the civilization, travel between stars will never be easy, or cheap. Which means that if something comes, it will be because they need to, they need food or something else. Cloaking might not be an answer, but the question is still there.
Gigel
1 / 5 (1) Apr 02, 2016
No matter how advanced the civilization, travel between stars will never be easy, or cheap.

I'm not sure it is so. If space behaved as a fluid, one could propel himself by simply sending the space fluid backwards. It would be possible to move at superluminal speed and stop with no deceleration by moving a local portion of space. There would be no energy expended on accelerating and decelerating.
Edenlegaia
5 / 5 (1) Apr 02, 2016
No matter how advanced the civilization, travel between stars will never be easy, or cheap. Which means that if something comes, it will be because they need to, they need food or something else. Cloaking might not be an answer, but the question is still there.


I wouldn't try to guess how aliens may travel in stars nor how much it'll cost them to do so. We don't even know anything about them, so, trying to figure out if they can travel so simply like we do with our cars or not.....
BartV
1 / 5 (3) Apr 02, 2016
The fate of humanity if aliens were to discover Earth...has long been a concern for scientists....


If this is the concern of NASA scientists, then I would say sack them all. This is just plan ridiculous. Worse than an April Fool's joke.

There are some very strange scientists out there.

Steve 200mph Cruiz
4 / 5 (1) Apr 02, 2016
What happens when they view our planet from another star system?

Also in order to travel around the galaxy, you would need a super computer that would have a detailed map of every meaningful mass source in the galaxy just so you could predict the location of wherever your target will be thousands of years in the future.
They would know about our planet already through galactic surveys.
In order to travel the galaxy accurately, you probably need to know the locations of most gas giants as well as stars.
Relying on the transit method would not be sufficient for the needs of an extra solar civilization
philstacy9
1 / 5 (2) Apr 02, 2016
When the aliens arrive kill them with massive lasers and then use the massive lasers and alien ships for Islamic jihad to conquer the universe and wipe out alien heretical religions. Allahu Akbar!
barakn
4 / 5 (1) Apr 02, 2016
Yes, it is an april fool's joke.

For starters, the lasers would have to be on all the time because we don't know where the aliens are coming from. Secondly, to fill in Earth's shadow using lasers, you'd need hundreds of terawatts.

The clue:
One MW can power several hundred homes for an hour.


Such a gross factual error can't be a honest mistake.

It's not a joke. They are assuming we know exactly where the aliens are, hence the need to light up the lasers for only 10 hours once a year, and the low power because we don't need to fill in the entire Earth shadow, only that portion of it that crosses the alien instruments. I'm assuming the gross factual error was made by Mariëtte Le Roux, not the scientists.

Of course this technique isn't going to hide the 3 other rocky planets or the gas and ice giants.
ogg_ogg
not rated yet Apr 02, 2016
I too thought this might be an April's Fools Joke. No, sadly it's not. The writer is simply incompetent or ignorant. An average US home uses about 900 kWh (note the units) per month of electricity. A 30 MW continuous LASER would be enough to cover the visible spectrum for the critical 10 hour transit time - assuming we knew which direction to point it. And the RAS press release was posted March 31. Time travel, huh? How about some time travel to get a rewrite? https://www.ras.o...m-aliens
Steelwolf
5 / 5 (1) Apr 04, 2016
The only problem with that is that laser light itself shows as being artificially produced, so it would more likely be like a brilliant sign that we are here. Yes, lasing does occur naturally, but not on that level in those wavelengths, it would be like an arrow pointing right at us!

And Scialot, that laser in Mote in Gods Eye, by Niven and Pournell, was for launching a light-sail ship, not for hiding their planet, in fact, it made their system VERY visible to outsiders.
Zzzzzzzz
not rated yet Apr 04, 2016
Not so much an April Fool's joke, as simply sad...... there are bigger planets than earth in our system, and we cannot "cloak" those. Then there are smaller rocky planets as well, besides earth - we cannot "cloak" those. Perhaps the RAS should be looking a little more diligently for more productive ways to spend their time.........I'm not at all sure Humanity will see this effort as "offering a choice"......
Shakescene21
not rated yet Apr 04, 2016
I too thought it was an April Fool's joke, but the author assures us that it's not. So we had better get started right away because the aliens are probably hundreds or thousands of light-years away, thus our cloaking lasers won't hide us for hundreds or thousands of years until their light reaches the aliens. :-)

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