As many as 6B Earth-like planets in our galaxy, according to new estimates | Hacker News Reader

As many as 6B Earth-like planets in our galaxy, according to new estimates

phys.org

44 pointsundefined142 comments

The estimates for the number of stars in the galaxy continues to grow. Just a few years I remember reading 100 billion stars, then it became 200 billion. And in this article it's 400 billion. And supposedly there are hundreds of billions of galaxies. One of the things I don't get is why did the universe have to be so big and unfathomable and spectacular? If it isn't teeming with life, feels like it's essentially one spectacular wasteland. Or alternatively, perhaps we are in a simulation?

If the whole universe happened by a cosmic accident, there's no one else around to care that it's mostly devoid of life. It's still entirely possible that life is a huge anomaly, and it only seems normal to us because we're around to witness it.

But random side question: is Mars considered "earth-like"? Or are these Earth-like planets even closer in composition and temperature to Earth?

> Or alternatively, perhaps we are in a simulation?

A relatively cheap one, considering that if this planet is the only one inhabited, the other star systems can be approximated and don't require full simulation.

Consider that time slows down when the speed is increased. This would be a good thing to do to restrict the computational requirements. And there's growing evidence that everything is quantized. Given that we probably can't measure anything smaller than a Planck length, that's the simulation resolution.

That's probably not what's going on (the simulation hypothesis could be the 'magnetism' of our era) but it is fun to think about.

Would if be computationally cheaper to just simulate our brains (our just one brain. Yours!) to give us the illusion the universe is whatever it is (quantized or not) rather than simulating the actual universe?

There is only one intelligent being in the entire universe. It's the entire universe, having a dream about being a human. And it's you.

What do you mean? Wouldn't you still need to simulate the world in pretty much the same way to be able to feed consistent inputs into the simulated brain?

There might be huge opportunities for pruning and approximation

You're just feeling like you're being fed consistent inputs :)

And if you ever feel otherwise, the simulation will be rolled back and fixed :-)

> A relatively cheap one, considering that if this planet is the only one inhabited, the other star systems can be approximated and don't require full simulation.

Maybe we're in a functional test of a simulation of a universe? That'd explain the lack of signals from other civilisations...

That would make sense, those kind of optimizations are common in video games. Objects with physics go to sleep when they stop moving. Things off screen don't get rendered. Culling of objects based on distance or zoom level. Lots of tricks like those.

If we assume we are in a simulation, surely it is simulating something 'known' (or familiar enough) like a universe with galaxies, stars, planets and life. And it is simulated by 'something'. So either way, it is unfathomable and spectacular. What is great in all of these views, is that everything goes really if you think about it, considering how little we know compared to the scale it.

Why do you assume that the simulation resembles the environment in which it executes? One can imagine cellular automata engines of enormous scale in which creatures could evolve. The simulated system need have no resemblance to the enclosing enviroment. Our universe could be a mathematical side-effect of some computation running in the enclosing universe.

Exactly!

A common refutation of the simulation hypothesis is that the computer would have to be impossibly large.

Not so. As long as the host universe has different physical laws. For instance, simulating Minecraft using Minecraft redstone logic itself would probably take an impossibly large "computer". Yet, we can do that easily, as we have nanoscale transistors.

Similarly, add just one more dimension to the host universe and you could build amazing machines (imagine instead of a 3D circuit board, a 4D, with all the extra arrangements it could provide). The host universe could be even crazier than this, with a whole different set of physical laws.

Unless we find a sandbox vulnerability, we'll probably never know.

Reminds me of "That Alien Message" on LessWrong: https://www.lesswrong.com/posts/5wMcKNAwB6X4mp9og/that-alien...

fantastic

It could also be a complete opposite of the executing environment, which is actually used to demonstrate the viability of 'another way to run a universe'. But because someone THOUGHT of this universe to simulate it, it's a "known" environment. If I try to break it down like a programmer, perhaps all it is, is a few physics rules programmed in, then the big bang on the enter key to execute the binary (I bet it's written in Rust - it's all the hype now). We could be done with a full universal simulation within maybe 1 hour of run time, but for us that 1 hour is like a trillion years.

Why do you assume someone thought of the simulated universe? As I said, it could be an accident, a side-effect of something else. Just as people inadvertently invent Turing machines when designing languages, our universe could be the side-effect of something built for an entirely different purpose.

The time scale could also be the other way around: An hour in the simulated universe could take a trillion years to execute in the host environment.

Maybe it's a simulation using a procedural algorithm that's still figuring out how to generate the conditions for intelligent life.

Or maybe the vastness of space and the physics that govern it (e.g., speed of light) ensures that life can never reach the end, or even see it. Kind of like how in Minecraft you can run in any direction and it'll just generate more land. Your run speed is no match for the Minecraft simulation.

It's still ultimately an unsatisfying idea though, since the next question is: What's outside the simulation? i.e., Where did God come from?

turtles

Another possibility is that the galaxy (and universe) is full of life, but the speed of light makes it impossible for life across the galaxy to interact.

There are many potential answers to the Fermi Paradox.

https://en.wikipedia.org/wiki/Fermi_paradox

The universe doesn't just have an incomprehensible size; it has also existed for so long that humanity's existence is a moment.

> One of the things I don't get is why did the universe have to be so big and unfathomable and spectacular? If it isn't teeming with life, feels like it's essentially one spectacular wasteland

That's probably a decent argument against the existence of a god

Maybe cause something like earth is a 1-in-kagillion chance

Off topic but I just want to give a shoutout to the astrophysicists in UBC. As an UBC undergrad alumni the physics department professors/TAs were probably the most 'caring' profs I had.

Jaymie Matthews is a hilarious professor according to my sister, and I was scheduled to take his classes...until he tried to save a random woman from an attacker in LV, went into a coma for the better part of a year, and pretty much missed all my classes.

From my very naive understanding, isn't there a belief that habitable planets are a bit more rare than we thought? Since most stars are red dwarves, the tidal locking zone overlaps the Goldilocks zone. Neither the abstract nor the phys.org article mentions tidal locking.

And don't forget the nasty flares that tend to fire up from red dwarves, either.

Yes, the article (and most articles of the kind; from what I've read) don't take into considerations those dynamical and astrophysical features. They search for Earth-sized terrestrial planets in a zone where liquid water can exist on their surface ("habitable" zone). Nevertheless even determining the abundance of those planets is an ongoing problem.

We're finding exoplanets at an incredible rate. See NASA's Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu/) for the current 4164 known exoplanets.

Related: The Very Large Telescope (VLT) in Chile just confirmed the existence of Proxima Centauri b, a roughly Earth-sized exoplanet in Proxima Centauri’s habitable zone—the closest star to Earth, just 4 light-years away! https://www.universetoday.com/146262/powerful-telescope-conf...

Oh, and here's this topic's prerequisite xkcd: https://xkcd.com/786/

(We write about exoplanets really frequently on https://orbitalindex.com)

Checking your site it seems there is an article weekly for two years now. That's amazing. Definitely recommend for anyone interested in the "space" field.

Bug report for https://orbitalindex.com/ :

In desktop Firefox 77.0.1, the page can be scrolled (i.e. the scrollbar is moving) for pages without anything happening. It took me a moment to notice that a content section can be pulled in from the right side. Disabling sanity-saving addons (ad-/tracking blockers) did not make a difference.

I can't wait for the James Webb Space Telescope to launch -- really excited to see what we've been blind to so far. Sadly, it's been delayed again due to COVID-19 (it was most recently scheduled for March of next year), but _whenever_ it launches it's sure to bring us eye-popping new images of space.

Hate to be a Debbie Downer, but Proxima Centauri B is likely not habitable due to its star blowing away its atmosphere.

https://phys.org/news/2018-04-proxima-centauri-flare-powerfu...

This was mentioned in the original article.

I can't help but post this Youtube video, for those never saw it:

Star Size Comparison 2 (watched 28M times)

https://www.youtube.com/watch?v=GoW8Tf7hTGA

Many of them are bound to have life on them.

The problem is we have only 1 data point. I think we ever get a second, then the likelihood of lots is much more imaginable.

That's the interesting question. Given a planet in the right place, what are the changes of life erupting per, say, 1B years? If its 1:6B, then we're likely alone.

Don't believe until you see them on Zillow.

Awesome. We can't possibly mess all of them up!

(But sadly, the Milky Way is still over 50,000 light years across.)

Don't underestimate us. I wouldn't be any money against human ingenuity in this regard.

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