Your comment led to an interesting chain of thought and another possible answer to the Fermi Paradox.
Given that not long ago we weren't certain that there even are planets around other stars and that now, as you say, we will soon be directly imaging the atmospheres of other planets, let's simply extrapolate that progress into the future.
What if we - and presumably other civilizations - develop the capacity to directly image other worlds as clearly and closely as our own satellites in Earth orbit do for us? If we could watch life on other worlds - it's environment, evolution, technological development - would we still consider the expense and hazards of interstellar travel justified?
Maybe no one's visiting because they don't need to.

No encounters: most ambitious alien search to date draws a blank

Astronomers who have been listening for signals from alien civilisations in the most intensive hunt for extraterrestrials yet have found no evidence of life in its first year in operation.

The Breakthrough Listen project began to eavesdrop on the universe with the Green Bank observatory in West Virginia in January last year, but the most intelligent transmissions the telescope has picked up so far appear to be from satellites or mobile phones and other earthly devices.

Data released by the project on Thursday revealed eleven of the most promising signals detected, but after close inspection scientists concluded that the radiowaves probably came from humans rather than other intelligent lifeforms.

“These are the signals that look most like what we’d expect to see from a distant technology, but when we looked at them closely were were able to determine that it’s most likely they’re interference,” said Andrew Siemion, the director of the Berkeley Search for Extraterrestrial Intelligence centre.

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No aliens yet for $100 million ET hunt

A $100 million search for intelligent aliens has come up with some intriguing leads but has revealed no evidence of E.T. so far.

Observations of nearly 700 stars by the Green Bank Telescope (GBT) in West Virginia revealed no compelling signs of alien civilizations, representatives of the Breakthrough Listen project, which led the observations for the E.T. search, announced April 20.

Team members also unveiled the GBT's 11 "most significant" observed events but stressed that these hits were probably caused by human technology. 13 Ways to Hunt Intelligent Aliens


"We were able to determine that they were most likely due to radio frequency interference," Andrew Siemion, director of the University of California, Berkeley's SETI (Search for Extraterrestrial Intelligence) Research Center, said Thursday during a presentation at the Breakthrough Discuss conference.

The new results are just the beginning for Breakthrough Listen , which billionaire entrepreneur Yuri Milner and a group of scientists, including Stephen Hawking, announced in July 2015. Over the next decade, the ambitious project aims to search the 1 million stars closest to the sun, the 100 galaxies closest to our own Milky Way, and the galactic plane for possible signals of intelligent extraterrestrial life.

Breakthrough Listen scientists are starting with an initial target list of 1,709 stars, which the team is observing with three telescopes: the 330-foot GBT radio dish, the 210-foot-wide Parkes radio telescope in Australia and the Automated Planet Finder, a 7.9-foot optical telescope at the Lick Observatory in California.

"This sample of stars is designed to be what we call 'spectral type complete' — it samples stars of every spectral type," Siemion said. "We want to look at as many different types of stars as possible, to leave ourselves open to any possibility that life might emerge [around] one of these stars."

The newly announced results, which the team submitted to The Astrophysical Journal on Thursday, are based on GBT data for 692 of those 1,709 stars. The telescope made about 5,000 individual 5-minute observations, racking up a total of 400 observing hours, Siemion said.

Those observations targeted a band of frequencies that includes the "water hole," a quiet part of the radio spectrum that SETI scientists have long speculated would be a good window for interstellar communication. The water hole lies between the emission band of hydroxyl molecules (OH) and that of hydrogen. Together, hydroxyl and hydrogen form water — hence the name.

"These results represent the most comprehensive and fundamental test of the water-hole hypothesis that's ever been conducted for nearby stars," Siemion said. "This is a classic idea in the search for extraterrestrial intelligence that's been with us for more than four decades."

Breakthrough Listen is part of the Breakthrough Initiatives, which Milner founded in 2015 to look for evidence of life beyond Earth and help spur space exploration. Another program under this umbrella is Breakthrough Starshot , which aims to develop a system that can blast tiny, sail-equipped nanoprobes to other star systems at 20 percent the speed of light using powerful lasers.

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Next year, scientists will send messages to search for aliens

For the last half-century or so, astronomers around the world have been scanning the cosmos with massive radio telescopes in hopes of finding some sign of intelligent life. This network of alien-hunters comprises the Search for Extraterrestrial Intelligence (SETI), but despite all their efforts, the interstellar radio waves have remained quiet. One might even say too quiet.

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Crypto-currency craze 'hinders search for alien life' - 14 February 2018
http://www.bbc.com/news/technology-43056744#

Scientists listening out for broadcasts by extra-terrestrials are struggling to get the computer hardware they need, thanks to the crypto-currency mining craze, a radio-astronomer has said.

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Apr 3, 1999 - May 3, 2020

Listening for Aliens, with Carolyn Porco and Dan Werthimer (Repeat)
https://www.startalkradio.net/show/listening-aliens-carolyn-porco-repeat/
May 1, 2018 • Season 3 Episode 9

Explore SETI and the Breakthrough Listen Initiative, the most comprehensive search for extraterrestrial intelligence ever, with host Carolyn Porco, co-host Chuck Nice, and Dan Werthimer, the Initiative’s principal investigator and SETI@home co-founder.

Is anybody out there? How would we know? And what happens if there is? Welcome to our second episode of StarTalk All-Stars, when host Carolyn Porco, and her guest Dan Werthimer, principal investigator of the Breakthrough Listen Initiative, answer your Cosmic Queries about the search for ET, chosen by co-host Chuck Nice. You’ll learn why Breakthrough Listen is the most comprehensive search for extraterrestrial intelligence ever, a new leap forward able to scan 10 times more of the sky and 5 times more of the radio spectrum, with 50 times greater sensitivity than any previous SETI project. You’ll hear about the search for life on the moons of exoplanets, as well as the possibility of microbial life here in our solar system. Explore the difficulties with the Drake Equation, which predicts the likelihood of intelligent alien civilizations, as well as the difficulties of designing instruments and spacecraft to detect life forms that could be quite different from us. Find out what a “second genesis” in our solar system could tell us about the chances for life in the rest of the universe. Carolyn and Dan discuss the protocols that are in place for responding to an alien signal and ponder an even bigger question: who should speak for Earth if we do make contact? Finally, dive into one of the most controversial issues being debated today: should humanity be broadcasting our existence to the galaxy at large, or is that a recipe for disaster that could end up with humanity’s enslavement…or worse?

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Apr 3, 1999 - May 3, 2020

https://www.nasa.gov/feature/nasa-is-taking-a-new-look-at-searching-for-life-beyond-earth

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Take a look at the "SetiSpirt" mapping of data, it might be what you are looking for.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Astronomer Jill Tarter discusses the search for intelligent life
November 2, 2018 by Colleen Walsh, Harvard University
https://phys.org/news/2018-11-astronomer-jill-tarter-discusses-intelligent.html

Excerpt:

GAZETTE: You talked about giving your listeners homework. My colleague mentioned to me an app that you could download to your computer that would help search for intelligent life while the machine slept.

TARTER: That's right. It was called SETI@home and it was developed at UC Berkeley. It's still going. It processes data that has been recorded at the Arecibo and Green Bank observatories. It runs as a background process on your computer and it really put citizen science and distributed computing on the map when it came out about 12 years ago. It didn't invent distributed computing—people were already doing that to break codes or factor prime numbers. But it was such a sexy application that everybody grabbed it and it took off and citizen science followed in its footsteps. It's a very large group of people who classify galaxies, who fold proteins for cancer research, who count craters on various pieces of real estate in the solar system.

(as we can see the article contains a few factual errors, but we can't complain ^.^)

If SETI uses off-the-shelf hardware & software for AI — can’t you?
VB Staff October 15, 2018
https://venturebeat.com/2018/10/15/if-seti-uses-off-the-shelf-hardware-software-cant-you/

Excerpt:

“We use gaming GPUs,” says Dr. Andrew Siemion, director of the Berkeley SETI research center. “We use the GeForce series from Nvidia. We use consumer level flash drives.” Siemion is one of the speakers at VB Summit, coming up on October 22-23 in Mill Valley, CA.

On Twitter, his team recently posted a photo of a giant box of empty GPU boxes and empty Samsung 970 Pro NVMe gaming flash drives, and piles and piles of other gaming components, he says.

“We made a joke on Twitter that we were building a new gaming system, when in fact we’re prototyping a digital spectrometer for a new radio telescope,” Siemion says (see it here -par). “It’s literally stuff that you buy at Best Buy. We’re just reprogramming it for a very different purpose.”

That’s right – the same technology that powers your Fortnite sessions is the part of the billion-dollar scientific program SETI – the Search for Extra Terrestrial Intelligence. Maybe you’ve heard of it, unless you’re one of the aliens they’ve been trying to find. Maybe you’ve even donated a little bit of your own computer’s processing power to SETI@home, to help the Team Human determine the prevalence and nature of intelligent, technologically capable life in the universe.

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Apr 3, 1999 - May 3, 2020

Tiny aliens may have visited us and we just didn’t know: NASA scientist

“Tiny, super-intelligent” aliens may have already visited Earth — but humans simply didn’t notice them, a NASA scientist claims in a new research paper.

Silvano P. Colombano, of NASA’s Intelligent Systems Division, argued in a recent research paper that extraterrestrials may look different than what we expect and may be able to travel huge distances — and so we may have never realized that they’d paid us a visit.

Silvano P. Colombano, of NASA’s Intelligent Systems Division, argued in a recent research paper that extraterrestrials may look different than what we expect and may be able to travel huge distances — and so we may have never realized that they’d paid us a visit.

“I simply want to point out the fact that the intelligence we might find and that might choose to find us (if it hasn’t already) might not be at all be produced by carbon based organisms like us,” Colombano wrote in “New Assumptions to Guide SETI Research.”

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“Tiny, super-intelligent” aliens may have already visited Earth — but humans simply didn’t notice them, a NASA scientist claims in a new research paper.

That's a very good point, and reminds me of an old Twilight Zone episode where we appeared as giants to the aliens. ;~)

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The mind is a weird and mysterious place

LOL:)
https://www.youtube.com/watch?v=cRfiBKPyn6U

Who is paying this guy's salary and who OK-ed the paper delivered in some journal. Another sign of Government incompetence and waste. Time to do a little house cleaning , Fur Sure Bubba !!

I have read the original article and could not find any referral to the size of aliens who may have visited Earth. Journalists may have misunderstood the article.
Tullio
I found nothing wrong with it.

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Silvano P. Colombano is a doctor of philosophy (1). Yes, he's also working at NASA's Intelligent Systems Division and he surely has the credentials for this kind of pay grade, but this said I must say that my dentist also has an opinion about wether aliens, great and small, populate the universe and visited us. But sadly, her interesting views are of no interest to the yellow press because she has no NASA credentials.

Now, I found his paper (2) on the importance for science of giving more space for the scientific investigation of "low signal-to-noise data" (the polite term for, say, UFO research and angelology?).

I simply want to point out the fact that the intelligence we might find and that might choose to
find us (if it hasn’t already) might not be at all be pro-duced by carbon based organisms like us. How might
that change the above assumptions about interstellar travel? Our typical life-spans would no longer be a
limitation (although even these could be dealt with multi-generational missions or suspended animation),
and the size of the “explorer” might be that of an ex-tremely tiny super-intelligent entity. And how might
this change our assumptions about openness or desire to communicate with other civilizations?

Fair enough. But I can see how the sensationalist press latched on tiny aliens visiting Earth.

In light of the challenges described above I propose a more “aggressive” approach to future SETI explora-
tion, in the following directions:
1. Engage physicists in what might be called “speculative physics”, still grounded in our most solid theories but with some willingness to stretch possibilities as to the nature of space-time and energy.
2. Engage technologists in futuristic exploration of how technology might evolve, especially w/r Artificial Intelligence, “Evolvable Robot-ic Systems” and symbiosis of biology with machines.
3. Engage sociologists in speculation about what kinds of societies we might expect from the above developments, and whether and how they might choose to communicate.
4. Consider the UFO phenomenon worthy of study in the context of a system with very low signal to noise ratio, but nevertheless with the possibility of challenging some of our as-sumptions and pointing to new possibilities for communication and discovery.

At this stage, I just wonder how NASA will justify keeping a philosopher who apparently fails to see the importance of evidence-based science on their payroll without paying a price at the credibility counter.

The only thing worse for NASA would be to have a creationist paid to advocate in favor of scientific studies seeking to count the number of angels dancing on the top of a pin.

1. https://www.researchgate.net/profile/Silvano_Colombano
2. https://ntrs.nasa.gov/search.jsp?R=20180001925

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Apr 3, 1999 - May 3, 2020

Colombano probably has a PhD degree. PhD means Philosophiae Doctor in Latin. But you can have a PhD in theoretical physics or aeronautical engineering, not in philosophy.
Tullio

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I have always a problem when filling some forms which require my academic level. I have a Laurea in Theoretical Physics but what is it in Anglosaxon terms? A BS? No. A Master? Perhaps. A Phd? not that I know In Italy there is the Dottorato di Ricerca, probably the equivalent of a PhD, but I don't have one.
Tullio

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My Laurea dates to February 1967. Its main results were published in Il Nuovo Cimento main body in September 1967. The article, by G.Bisiacchi et al cites my thesis. The title is "SU(N,1) representation for the harmonic oscillator".

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Yes Chris, thanks. I have also worked in the Experimental Physics Laboratory before graduation, managing radioactive substances (CO60) without any protection or insurance. I used it to get neutrons to calibrate a bubble chamber built for International Atomic Energy Agency, whose electronics I shifted from vacuum tubes to transistors. I was the first to use Germanium transistors in Trieste in 1960.I have it as a memory because I fell in love with a blonde girl who was scanning bubble chamber photos from CERN. She typed her results on IBM cards and we brought them to the only computer in Trieste, a UNIVAC machine. But we also took some ice cream on the way from the University to downtown. Cheers, and thanks again.
Tullio

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