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Observations made in 2013 by University of Wisconsin–Madison astronomer Amy Barger and her students showed that our galaxy, and much of the Laniakea Supercluster as well, resides in a great cosmic void. Building upon this work of his adviser, Ben Hoscheit made observations of 120,000 galaxies to measure how the density of galaxies changes with distance from the Milky Way. The findings, presented at the June 6 meeting of the American Astronomical Society, show that the Milky Way indeed resides in a vast cosmic abyss some two billion light years across, with the Milky Way being within a few hundred million light years of its centre, where galaxies are much fewer and farther between than in most of the rest of the universe. This could explain the discrepancies between measurements of the Hubble Constant which use relatively nearby supernovae and Cepheid variables to measure it (71.9 ± 2.7 km/s/Mpc) and those which use more distant observations like the cosmic microwave background (67.74 ± 0.46 km/s/Mpc). The nearby supernovae and Cepheids would be accelerating more quickly and yielding that bigger value for the Hubble constant because they are feeling an extra gravitational pull from the matter at the edges of the void we are in. This obviously does not affect the CMB or anything much further away. From the UW–Madison press release:
Cosmologically speaking, the Milky Way and its immediate neighborhood are in the boondocks.
In a 2013 observational study, University of Wisconsin–Madison astronomer Amy Barger and her then-student Ryan Keenan showed that our galaxy, in the context of the large-scale structure of the universe, resides in an enormous void — a region of space containing far fewer galaxies, stars and planets than expected.
Now, a new study by a UW–Madison undergraduate, also a student of Barger’s, not only firms up the idea that we exist in one of the holes of the Swiss cheese structure of the cosmos, but helps ease the apparent disagreement or tension between different measurements of the Hubble Constant, the unit cosmologists use to describe the rate at which the universe is expanding today.
[…] The tension arises from the realization that different techniques astrophysicists employ to measure how fast the universe is expanding give different results. “No matter what technique you use, you should get the same value for the expansion rate of the universe today,” explains Ben Hoscheit, the Wisconsin student presenting his analysis of the apparently much larger than average void that our galaxy resides in. “Fortunately, living in a void helps resolve this tension.”
The reason for that is that a void — with far more matter outside the void exerting a slightly larger gravitational pull — will affect the Hubble Constant value one measures from a technique that uses relatively nearby supernovae, while it will have no effect on the value derived from a technique that uses the cosmic microwave background (CMB), the leftover light from the Big Bang.
[…] The void that contains the Milky Way, known as the KBC void for Keenan, Barger and the University of Hawaii’s Lennox Cowie, is at least seven times as large as the average, with a radius measuring roughly 1 billion light years. To date, it is the largest void known to science. Hoscheit’s new analysis, according to Barger, shows that Keenan’s first estimations of the KBC void, which is shaped like a sphere with a shell of increasing thickness made up of galaxies, stars and other matter, are not ruled out by other observational constraints.
“It is often really hard to find consistent solutions between many different observations,” says Barger, an observational cosmologist who also holds an affiliate graduate appointment at the University of Hawaii’s Department of Physics and Astronomy. “What Ben has shown is that the density profile that Keenan measured is consistent with cosmological observables. One always wants to find consistency, or else there is a problem somewhere that needs to be resolved.”
Other coverage at ScienceNews, Starts With A Bang, and Wired.
(Score: 0) by Anonymous Coward on Thursday June 08 2017, @09:30PM (11 children)
So that's why no-one is answering the phone... no-one wants to talk to us hicks.
See https://en.wikipedia.org/wiki/Fermi_paradox [wikipedia.org]
(Score: 2) by Grishnakh on Thursday June 08 2017, @09:46PM (10 children)
Exactly. We're in a backwater part of the universe, not near enough other galaxies for there to be any advanced intelligent life around. So our species is going to destroy itself and the planet it lives on before it even manages to achieve interstellar travel (let alone intergalactic), and no other races will ever even learn about us because we're so far out in the Void. Oh well.
(Score: 4, Insightful) by takyon on Thursday June 08 2017, @10:27PM (2 children)
We monitor only a tiny portion of the electromagnetic spectrum at any given moment. We are in the process of switching from radio to laser communications with our distant spacecraft. There have been numerous reports throughout recorded history of unidentified flying objects. We haven't located all of the small objects in the solar system, and we are many decades away from having good imagery of most Jupiter trojans, trans-Neptunian objects, etc. There may be a gas giant less than 1,000 AU away that we have not discovered. We don't know what's "out there", and we haven't finished discovering stuff nearby.
The big clues will come when we start to routinely examine exoplanet atmospheres or even surface features, and if we start spreading to other rocks. If we find exoplanet atmospheres that indicate vegetation, we can refine the Drake equation just as the Kepler spacecraft did. If we have colonies on at least 5 worlds (such as the Moon, Mars, Ceres, Callisto, and Titan), then we can start thinking of humanity as a species that is both resistant to collapse (but not immune since a nearby supernova could ruin things) and tends to spread outward. If you can put a self-sustaining colony on Callisto or Triton or Pluto (with very little reliance on solar power), then you can spread to almost any icy rock in the solar system.
The Alpha Centauri system is moving closer to our solar system over the next tens of thousands of years. There is no rush to get there because it will become slightly easier to do so before any serious attempt is made, even if it takes 500+ years. We may manage to get humans or embryos there intact, with the necessary shielding from interstellar protons and a spacecraft that has the right combination of long-term reliability and high velocity. Once colonies can be established there, humanity's decision making will become more diverse (even if a few worlds sentence everyone to VR prison, other colonies can continue to replicate to other rocks) and the species will become even more resistant to collapse since an interstellar war would be inconvenient and a rogue planet encounter would be unlikely to wipe out life in both systems.
The point is that humanity has to prove on its own that intelligent life is capable of surviving and willing to eventually spread across a radius of X light years. If humanity can establish itself 5-100 light years away, then alien civilizations could as well.
I believe that we won't have to establish any colonies before we get a much clearer picture of what's going on. We have only discovered exoplanets since 1988 [wikipedia.org]. HARPS and the Kepler space observatory have helped us to begin filling in the Drake equation probabilities. The James Webb Space Telescope and other telescopes will help us to characterize exoplanet atmospheres. We still don't have huge ground telescopes on the far side of the Moon yet. We don't have the High-Definition Space Telescope or Advanced Technology Large-Aperture Space Telescope funded yet. Breakthrough Listen [wikipedia.org] just started:
That's good, but still not very far.
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(Score: 2) by Grishnakh on Friday June 09 2017, @01:44PM (1 child)
There have been numerous reports throughout recorded history of unidentified flying objects.
Yeah, probably mostly easily explained by meteors, drunk people, etc.
Notice how there were lots of reports of UFOs several decades ago, and now there's none? Simple explanation: we were visited by ETs for a time, but now they've decided we're beyond hope and have given up on us, for good reason too.
If we have colonies on at least 5 worlds
That'll never happen. Not because it's physically impossible (it's certainly not, it's not even *that* hard), but because we're too dysfunctional as a species to do it.
The point is that humanity has to prove on its own that intelligent life is capable of surviving and willing to eventually spread across a radius of X light years.
*Truly* intelligent life is capable of that. We don't fit that description however.
(Score: 2) by takyon on Friday June 09 2017, @08:23PM
https://news.google.com/news/section?q=ufo [google.com]
There are plenty. MUFON, etc. still exist and get plenty of reports. Many reports hit the news but they are often local rather than national stories. Plenty of videos hit YouTube. But there's such a sea of crap out there that it may be impossible to tease out anything real even if you desperately wanted to. It's a lot easier to create a fake UFO video than it was even 5 years ago.
Some people are probably keeping their reports to themselves.
The drone age could muddle things even more.
Oh, you were using this as an opportunity to bash humanity. Well, we'll just bring our despair to the aliens instead.
We can get probably get a lunar and martian colony initiated within the next 30 years. There is definitely some dysfunction slowing it down, but China seems interested in expanding the scope of its space
raceprogram so not all eggs are within in one funding basket anymore.These colonies don't even need to have that many people. Under 10 people is OK. They are the seeds of infrastructure that could eventually grow into real communities. What's most important is for some living quarters, agriculture, and hopefully industry to be established. Colonies on other worlds need to be self-sufficient and capable of producing their own water from ice, plastic, metal, etc. Some allowances can be made. For example, manufacture 95% of a robot's parts on-site, with the exception of tricky but low-mass components like CPUs. You can bring a bunch of those from Earth.
You're a little too pessimistic, I think. SpaceX is trying to send an Interplanetary Transport System to Mars within about 10 years. Originally they planned to send a manned mission there by 2024, but it could be up to 2030 now. 13 years is not a long time to wait.
Grishnakh doesn't get to decide whether humanity is incapable of spreading to multiple worlds. Only time will tell, but the results should be apparent within 50 years and the 5 worlds colonized goal ought to be achievable within 100. The Moon and Mars will be the first tests.
If you want a little ray (kurzweil?) of hope, humanity can be replaced. The capability to alter the human genome to create a species with more intelligence, more tolerance to space radiation, etc. is just around the corner. You could go the cyborg/augmented intelligence route or just send AI. Even if all of humanity dies, as long as one of these new species or machines exists, humans could be recreated from scratch using a DNA sequence. I wonder if Grishnakh would make a good pet?
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(Score: 2) by bob_super on Thursday June 08 2017, @10:31PM (1 child)
You're just a temporary arrangement of matter drifting towards oblivion in a cold uncaring universe ... and to drive the point home, God put you inside the biggest known hole in the universe.
Go hug your wife-beating Sunday-morning-powertools fanatic Harley-riding neighbor, for he is the only close thing in the whole universe.
(Score: -1, Troll) by Anonymous Coward on Saturday June 10 2017, @11:40AM
> God put you inside the biggest known hole in the universe
that would be your mom? explains the global warming trend tho
(Score: 3, Informative) by zocalo on Thursday June 08 2017, @10:35PM (3 children)
UNIX? They're not even circumcised! Savages!
(Score: 2) by takyon on Thursday June 08 2017, @10:55PM (2 children)
We aren't monitoring the entire night sky constantly for transmissions across the entire electromagnetic spectrum. Intelligent broadcasts may be hard to detect for reasons we don't expect. We're also in the process of transitioning to lasers for deep space communications [nasa.gov]. If aliens use lasers to communicate, those could be harder to detect. If they use ansibles, we're just screwed.
We're still looking for a gas giant planet less than 1,000 AU away from Earth. Our understanding of what's going on in the Milky Way is incomplete.
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(Score: 3, Interesting) by zocalo on Thursday June 08 2017, @11:46PM
If, however, we replace Fc (detectable comms) with a more generic "detectable evidence of existance", e.g. specific compounds in the biosphere or even evidence of Dyson structures if you are a fan of that proposal for the dimming of Tabby's star, then we have some more options to work around that lakc of detectable EM. That's where a lot of the focus for hunting for evidence of life (any life, not necessarily sentient) is currently focussed, and as that tech improves the value of L should start to climb, and with it our chances of finding some evidence for sentient life, even if we have no idea how we might communicate with them should we be inclined to try.
UNIX? They're not even circumcised! Savages!
(Score: 2) by c0lo on Friday June 09 2017, @01:42AM
One of such reasons: we can look at the night sky all we want, the aliens are more intelligent than us, value their night sleep and transmit only during the day.
(grin)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Friday June 09 2017, @06:32AM
Perhaps they came, encountered the mental virus that religion is and have us isolated until we fix it ourselves