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Chart of the Milky Way Includes More Than 1B Stars (scientificamerican.com)
110 points by artsandsci 9 months ago | hide | past | web | favorite | 72 comments

I love thinking about the sheer scale of it all. This is a billion stars of the ~200-400 billion stars in our galaxy. The Andromeda Galaxy (the closest to us) has ~1 trillion stars.

There's an estimated 100 billion planets in the Milky Way alone, and who knows how many in the Andromeda galaxy.

There could be another satellite somewhere in this galaxy charting space just like this and we'd just be a bright dot to them among billions of other bright dots.

One either hates those comparisons or loves them, I personally like them because a hundred billion is way to abstract for me. If you fill your 50 m² apartment to a height of 1 m with table salt, then you are looking at 400 billion grains of salt. [1]

[1] I once counted the grains in 1 cm³, there were pretty much exactly 8000 of them ignoring the very fine powder from crushed grains. 1 m³ of table salt gives you pretty much one grain of salt for every human on earth.

Excellent visualization, however you have to use the units of measurement appropriate for a space faring people who have visited the moon.

So your 500 sq ft apartment is filled to a height of 3 feet with salt. That is 400 billion grains of salt.

More relevantly, those are the units of measurement of a space faring people who later crashed because they couldn't keep their units straight.

I actually thought about including imperial units - which seems not to be quite the correct technical term as I just found out - but did not want to encourage their further use and therefore decided against including them.

I really had no idea that people that asked for others to use imperial units existed…

... and yet in the US, most still do that outside of tech environments. Try ordering cement by the cubic meter.

My gawd, it's embarrassing.

Have you seen Hubble's high-res Andromeda image? It's amazing for sense of scale [1]. Zoom in - every bit of "noise" is a star.

It's also downloadable in full res [2]. Maybe use the torrent option to save their poor servers.

[1] https://www.spacetelescope.org/images/heic1502a/zoomable

[2] https://www.spacetelescope.org/images/heic1502a

There could be a google maps for this, like there is https://www.google.com/moon/

The same picture but in a video with a very fitting song imo: https://vimeo.com/124610461

I love thinking of all this cosmic reality boiled down to a single ~100GB CSV file.

Or a 1TB XML file...

Last time I looked into this the current estimate is that there are on average 10 planets per star, so we have 1-4 trillion planets in our galaxy, and there are 10 trillion planets in Andromeda.

The Universe is teeming with galaxies, which are teeming with planets. Given what we know now it is likely that they are teeming with life (organisms in a process of self-sustaining and self-generated action) as well.

The majority of those planets are unsuited to anything we can imagine being alive, or only suitable for very simple unicellular life. Most of those plants are gas giants, or blazing hot gas giants. Some are rocky, but many of those are in orbits like Mercury, which would alternately bake and freeze them. Of course, part of the reason for this might be our detection methods, but as of now, we’re not finding. I hope like Earth, Venus, or Mars, while we find a lot of Jupiter’s. Maybe we’ll disocver that something like bacteria is ubiquitous, but that doesn’t imply much for our prospects of finding intelligent life. For all that we know life is common, but multicellular life is incredibly rare, or maybe it isn’t rare, but intelligent life is.

There are billions of galaxies though, so even if we are the only planet out of billions in our galaxy with complex life, there could still be billions of civilizations out there!

For that matter, the typical planet with life could be too large and have too thick an atmosphere for space travel or astronomy and thus never have any idea the rest of the universe exists. That wouldn't necessarily mean life was limited to single cells.

Just about "alternately bake and freeze" (no opinion on the rest): Mercury does spin (slowly, every 60 earth days; previously was thought to be tidally locked), but on the other hand it's not tilted with respect to the "ecliptic plane" (the plane in which the planets orbit around the sun). It turns out it has water ice at the poles: https://www.space.com/18687-water-ice-messenger-discovery.ht...

There's this great article I came across a few weeks ago:


About how we may expect life to be more prevalent than it is because our own existence is so miraculous. Though the other side is - if the universe is so large, with so many planets, then there may be a chance that there's life out there that's just as incredibly lucky as us.

I've always liked to entertain the idea that highly advanced intelligent life is an evolutionary dead-end. After all if human beings drive themselves to extinction in the next 10,000 or 50,000 years what did our intelligence get us? It didn't enable us to survive better than other species.

And what if a lot of intelligent species run into this problem? Where the level of knowledge and power they amass far outstrips what they've evolved to responsibly handle. And the result is intelligent species often manage to destroy themselves before they become wise enough to avoid that.

I constantly hear people saying we're going to make ourselves extinct, but have you ever stopped to think about how hard that is?

We're the most adaptable species ever to live on this planet . There are 8 billion of us on every continent except Antarctica, and we've found ways to codify and share our collective knowledge.

Climate disasters, widespread thermonuclear wars, etc would be horrifying and would likely kill a great many or even a majority of humans. But even that wouldn't do much more than slow us down a few hundred years.

Even an a massive impact from space on the scale of the Chicxulub impact would kill off most people, and collapse civilization - but we'd rise again in less than a thousand years.

It's very hard to think of a scenario that would actually end us. One thing I've speculated about is maybe we unlock some awful power that we can't control. For example, if it were easy for anybody to distill antimatter in their garage in large quantities. Because there are always going to be those among us who want to burn it all down and who would destroy everything if they could. In a hypothetical world where terrorists and rampagers attacked with kilograms of antimatter, that might make it difficult to maintain a level of civilization for long periods of time.

> but we'd rise again in less than a thousand years.

Would we though? I am not so sure starting from scratch is going to possible. For example, all the easy oil is gone. All the easy mining, is gone. We can get at it because we have the technology.

If 99% of the human species was wiped out, yes we would continue to exist, but I would not expect many great civilisations to flourish again

The bit about energy sources is true, though a little spun. It's true that oil is gone. Coal is still plentiful, even at the surface. And the "hole" in industrial development where we depended on oil specifically has been less than 100 years or so, and already seems to be reaching its end. It's not impossible to imagine a future society skipping liquid fuels (and most of aviation) and still making its way to the renewable revolution.

> All the easy mining, is gone.

This bit is wrong, though. You can literally walk through a demolition site and pick up rebar and aluminum by the ton. Access to a single ancient reactor would give you the equivalent of decades of mining from any single uranium site. All our city building has had the effect of concentrating easily exploitable "ore" resources, not depleting them.

I was probably over generalising (and I really have no idea about this tbh). But I would still think a lot of the easy mining is gone.

>Access to a single ancient reactor would give you the equivalent of decades of mining from any single uranium site

What could is uranium to destroyed civilisation where all previous knowledge has been lost? I don't think future post civilisation peoples are going to be reconstructing a nuclear reactor from wood.

>You can literally walk through a demolition site and pick up rebar and aluminum by the ton

Post civilisation people are not going to have much use for demolished materials. Yes with modern technology we could reuse it. But how will they use it? I've seen a build demolished in the third world. People came and got the pieces of rebar true, hammered the concrete off it, but only to sell, not to use. I don't really think in a post civ world it would be of much use

> It's not impossible to imagine a future society skipping liquid fuels (and most of aviation) and still making its way to the renewable revolution.

Impossible? Perhaps not, but still very very unlikely. For decades after the event, survival will be all encompassing. Knowledge will pretty much have disappeared. You talk about skipping liquid fuels and aviation and going straight to renewables. First people will need to invent electricity again - everything will need to be "invented" again from a much weaker starting point. I just don't see it happening. Much more probable it is the end of human civilisations / humans as the dominant species on this planet

> But I would still think a lot of the easy mining is gone.

Again, you have completely lost me. Can you explain again why you think it's easier to dig up and smelt natural iron ores (or copper, or whatever) than it is to find an old rusty engine block or electric motor and just use that? Civilization needs metal to develop, in this example, not "mining". And ours has already done the mining!

We don't need mining - The metal in junk yards and recycling centres are a lot easier to access than building a mine in the middle of nowhere going underground 50 to 100 metres. The only reason we do mine and need new metal is because metal from junkyards and recycling centres are needed as well, and all existing metal is already being used. If most humans die off then the existing metal are available for reuse. And it's as easy as heating it up past melting point and molding it into the right shape; There might be ways to do that optimally but in the case where plentiful resources are available compared to human capital, it should suffice.

The oil is gone, but coal is still easy to access. We can bootstrap off a second coal industrial revolution. And every person who've been through high school knows the principles involved in generating power from coal, though might be lacking in the actual techniques.

> but only to sell, not to use

You've proved there's buyers who would find a use for it.

> You've proved there's buyers who would find a use for it.

You seem to be falling into the romantic view of post apocalyptic event. The world doesn't stay the same as it is now, just with the people gone. There is no one to buy your scrap metal. There is no more organisation, there is no more nothing.

> And every person who've been through high school knows the principles involved in generating power from coal

No they don't. They may know coal can be involved, but they have no idea how to take coal and make electricity. I assume you are a technical person working in a technical role. Go to your local supermarket and ask the person at the till for the basic principles involved.

If they just graduated high school they’d remember their science classes. The coal burns, it generates steam which rotates some magnets and produces a current. If they’re fresh high school grads they might even have the textbook at home still.

The maker culture contradicts your hypothesis. I have a friend who has for decades run his own little metal furnaces. By comparison to the modern industrial refining processes, his are primitive. But they are easily built and work well for the individual.

There is plenty of information available today that allows one to rebuild some level of technology very quickly.

> There is plenty of information available today Last time I looked today, we were not in a post civilisation world. This information will be gone. How is information going to survive an event that wipes out 99% of humanity? No power no rule of law. The sole concern of the remaining people is to get food and get to an environment they can eek out an existence. The information of today will be all but gone.

> I have a friend who has for decades run his own little metal furnaces. By comparison to the modern industrial refining processes, his are primitive. But they are easily built and work well for the individual.

Sure, but how many people have this knowledge now? How many people will be left with this knowledge after:

a) the event itself b) after years of struggling to survive and finally being able to more than subsist

First priority food and shelter. Food, you can scavenge supermarkets, but eventually it will run out. You will need to grow your food by hand. You will need to find seed and be successful otherwise it is hunter gatherer lifestyle, with assumed hunting is minimal as whatever wiped out 99% of humanity did the same to other animal species.

But lets say you found a good piece of land where you could survive, it would take years. Lets suppose you were one of the few people who knew how to build a furnace. Are you going to leave your patch of land to go wondering in the remnants of what was left of the city to get some scrap metal to carry back? I don't see it happening. Then in a generation of what was was is forgotton

The knowledge won't all die with us. And we will be quick to reverse engineer and reinvent things again. We don't need oil, we've got coal, hydro, wind, and solar (both concentrated solar and solar panels), and we have biofuels. With most humans dead, arable land won't be in short supply.

> We're the most adaptable species ever to live on this planet.

I'm not sure we've been around long enough for such a bold claim. Afaik there's plenty of life on Earth that outdates our existence by magnitudes.

It's got nothing to do with how long a species has been around. But no species survives in such a wide range of climates and habitats as humans.

> It's got nothing to do with how long a species has been around.

If you are talking about species to "ever live on this planet", then how long a species has been around being a pretty big factor in determining how adaptable a species is.

And in that regard, homo sapiens is rather a newcomer. Even our ancestors have only been around for a meager six million years.

While other species, many of them oceanic, have been around for hundreds of millions of years like sponges (580 million years) Jelly Fish (550 million years). Cyanobacterias are actually the oldest known living system in the world, originating 2.8 billion years ago, technically the oldest life on earth.

Compared to those, humanities existence is literally just a second on the clock of Earths history.

I've probably missed something obvious here, but what about Tardigrades and bacteria?

The problem with us is our size. We're one of the biggest animals, and that means we're particularly vulnerable to ecosystem collapse.

I think "intelligent" is perhaps the wrong adjective to distinguish humans. I would suggest "social" is a better one, as we are to other primates what ants or bees are to nonsocial insects. It's not the intelligence of the individual so much as the "programmability". Thus, I doubt it's an evolutionary dead end, as when you look at social organization from a broader view, it's developed in many different species. Even multicellular life itself seems like social organization at a lower, earlier level of abstraction.

I would agree that an interplanetary/interstellar civilization is something that may never come to pass, but I don't see it as a judgement on the capacity of particular life on earth to adapt, but rather a result of the physical laws that constrain all life, particularly delta-V and the speed of light.

It's interesting how insightful, thoughtful comments like this get modded down to hell on HN because they offend someone's religious beliefs. You're right, all evidence so far does point to us driving ourselves to extinction eventually, and the way things are going, it's likely to be a lot less than 10k years. And the idea of other intelligent species running into this problem isn't a new idea, it's long been a theory among searchers of extraterrestrial life, called the "great filter theory".

The idea that humanity is sinful and unworthy and the end of the world is near or at least inevitable has a very long and deep religious background. Yet these themes frequently crop up among those who are making a point of the inferiority of religious thought. I have a certain distaste for how much people apparently love to think in terms of labels rather than substance.

I often think downvoting is overdone, though.

>The idea that humanity is sinful and unworthy and the end of the world is near or at least inevitable has a very long and deep religious background.

Really? I haven't seen that at all. If you're talking about Christianity and the whole "end times" stuff, that's a little different: that isn't humanity "driving itself to extinction", that's some deity deciding that humans are bad and proactively eliminating them. I don't see that as the same thing at all.

In fact, why I said this seemed to be offending peoples' religious ideals is that I think the idea of humans making themselves extinct directly counters this religious idea that a deity is the one in charge of humans' fate. To them, if humans are all eliminated, it can't possibly be because humans did it to themselves (as this is what they'd call a "humanistic" or "secular" idea), but could only happen because their deity made it so. And conversely, as long as humans are "good" enough (meaning they worship the deity enough, nothing about them wrecking their environment or obliterating themselves with nuclear weapons) then the deity will protect them from their own mistakes.

"Humanity" as an entity with purpose or a mind is substantively the same as a deity from my perspective.

It's an abstract concept that is analogous to a single human, that is supposed to exist without a specific location in space and time, and has free will, causes things to happen and/or is blamed for them. And I see the same lack of empirical evidence for the concept.

So, yes, you may not see it as the same thing, but I quite definitely do.

Are you arguing? I only mentioned life, not degrees of complexity of life.

Ponder this: how early did life appear on Earth? what later cataclysmic events did it survive through the next several billions of years? how many living organisms are there on Earth at the moment?

Finally, how you imagine life can exist or can appear is not equivalent to the facts of life on Earth, let alone in the entire Universe.

Wondering if giants like UY Scuti have planets and how big.

Red supergiants are necessarily no more than about 25 million years old; they keep ejecting a lot of material, forming nebulae; and then they end as supernovae. So, unlikely to have sufficient time and relative calm to form and maintain planets.

It's fairly unimaginable almost to a human, even our own tiny solar system in comparison is gigantic...

This video is a really good example of how to sort of wrap your head around just that: https://www.youtube.com/watch?v=Kj4524AAZdE

Since the article seemed to neglect actually linking to the data, it is publicly available here: https://gea.esac.esa.int/archive/

There's an incredible decade-old map that shows space around the centre of Earth on a logarithmic scale - it's detailed enough to show the core, mantle, and crust at the bottom, and the Great Walls at the top:


I finally got round to printing a two metre tall version of this to hang in my hall a couple of weeks ago!

It makes me sooo sad that (whoever) introduced this stupid light speed limit so we can’t visit those places. Ever. Maybe in the next reality.

If you can invent a way to continuously accelerate at 1G, you can reach anywhere in the known universe within a human lifetime.

Within your lifetime, rather than that of an arbitrary human on Earth.

nit: most of the observable universe is not reachable even at the speed of light (search Hubble Volume for more info).

As an omnipotent creator, other choices in physics and the arrangement of matter would have other drawbacks. The problem of invasive species destroying unique ecosystems on earth is widely recognized, and if you were designing a universe where interstellar travel was easier, then the scale of the problem would increase.

I guess it’s all about making hard choices

That's a limiting factor in our current form factor. We so far have yet to identify a similar physics-bound reason preventing us from transferring consciousness and identity to a different substrate, or even a computing substrate for that matter. Admittedly, we still are in the very early stages establishing exactly what consciousness and identity are, so it is premature to claim that we can perform the transfer in the future. The most we can assert at this moment is based upon the laws of physics as we know them today, we can hold out more hope for transference than breaking c.

Similarly, we are not aware of any physics-based reason that prevent the design, construction and maintenance of computing substrates that renew themselves over billions of years. There are certainly political, cultural, social, even energy limitations, but nothing quite as hard as the c limit.

So theoretically, we can hope to even in this reality to eventually create versions of our selves that reside in computing substrates and "wake up" for "interesting" events along a multi-million year journey. Perhaps they run in a low-power mode, where 1 day in real universe == 1 second in the substrate. In that context, even if we never go faster in that future than our current technology's Juno space probe, a trip to Alpha Centauri is "only" 17,785.27 years, or 12.35 years subjective substrate time, enough to get excited about and study the torrent of increasingly-fine-grained data pouring in from the real world about the destination.

If the galaxy is relatively teeming with these compute substrate hibernation ships, then that presents interesting possible resolutions to the Fermi Paradox: what we are doing today on Earth is not "interesting" enough to the automation on these alien ships, or we are deemed interesting, but even the nearest ship within our light/EM cone is still thousands to tens of thousands of years away.

It gets even more interesting if we figure out how to "decant" substrate consciousnesses into physical bodies.

Even at that glacially-slow crawl of the Juno space probe, it would still take "only" 383,551,218 years to traverse the Milky Way's 100,000 light years. Put up against the ~13 billion years of the Milky Way's existence, that means spreading across the Milky Way is still within the realm of not-ruled-out-by-physics.

Even if you could transfer your consciousness into an immortal machine and stick it on a starship, if it takes billions of years to traverse the galaxy because the ship is so slow, that just isn't that practical: by the time you get to a far-away star system, the star might have gone nova, the planet you wanted to see destroyed somehow, the lifeforms there killed themselves in a nuclear war, etc. The milky way galaxy alone has changed a good amount in the last few billion years: Earth certainly didn't look anything like it does now 4 billion years ago. If it takes you that long to get anywhere, it'll really limit what you can see: you'll be facing the heat-death of the universe before you've gotten out of the galaxy. I see your estimate about Juno's speed, but remember, if you're actually trying to explore the galaxy, you aren't just going from point A to point B, you're going to take a very long, circuitous route so you can see lots of star systems. There's ~400M stars in this one galaxy alone; how long would it take a Juno-speed starship to see even half of those? As an analogy, it only takes me 3-4 days to drive from the east coast to California, but if I want to see every city of at least 25k people between here and there, it's going to be a much, much, much longer trip.

At least it's given us time and space to evolve consciousness on our own?

Yeah... true. Space, Time and matter are quite nice

I don't have the patch notes for reality to hand, but i assume it was a similar hack to the time dilation in Eve:


Our telescopes and other instruments are getting more powerful. All we have to do is look...

That's not that useful. It's great for looking back in time to see the origins of the universe, but if you want to communicate with someone on a planet 100 light-years away, that's a 200-year round-trip latency. And telescopes will likely never be powerful enough to see, for instance, the actual inhabitants of another planet (we'd be lucky if we could see some gigantic Death Star-sized space station optically).

>And telescopes will likely never be powerful enough to see, for instance, the actual inhabitants of another planet (we'd be lucky if we could see some gigantic Death Star-sized space station optically).

gravitational lensing by Sun, just need to put the telescope at least 550 AU from the Sun.


"And using the Sun as a lens would result in much greater magnification. Instead of a single pixel or two, astronomers would get images of 1,000 x 1,000 pixels from exoplanets 30 parsecs, or about 100 light years, away. That translates to a resolution of about 10 kilometers on the planet’s surface, better than what the Hubble Space Telescope can see on Mars, which would allow us to make out continents and other surface features."

To the GGP point of light speed limit - that is only true for static fixed spacetime. The spacetime expansion/contraction doesn't seem to have that limit (this is how we have far-far galaxies receding from us at the speeds higher than c). Just an issue of engineering that into a practical drive ...

By definition, if we can extend our lifespans long enough for a person to travel 100 light years, we can wait the 100 years it takes for a signal to arrive.

You're not going to have a very good conversation with a 200-year latency. A normal conversation requires many messages on both sides. 1 year isn't that much of a human lifespan, but if we tried to hold a conversation with a 1-year round-trip latency, it's not going to be a very good conversation; it's just too long between messages. But if you just want to blast them with a ton of information all at once (like sending them a bunch of video archives and a copy of Wikipedia, for instance), that's doable, but it's not a conversation.

They are similarly limited by light speed (in the other direction)

Superb stuff. On a more mundane level I hope we'll soon also have a chart of all the asteroids in our solar system (to the most realistic extent possible).

Here's a video showing the discovery of 600,000 asteroids in the inner solar system - https://www.youtube.com/watch?v=2k2vkLEE4ko

Thanks! Took me a minute to work out which planet was which (Jupiter being the one just outside the 'belt').

It’s not mundane to me when you consider how much mineral wealth is just out of reach.

I guess he implied mundane on a scale level :)

This may sound odd, but does anyone know of a public dataset that provides the positions of stars and their relationship to other stars? I'd be curious to see this type of data.

I think that there must be many more than 1bn though? The area of the disk is roughly 3.14^10 light years, and it must be 10K light years thick on average so 3.14^14 cubic ly... stars seem to be much more densely packed on average than 1 per cubic ly but if we assume that Sol is the measure then the nearest star is not in a 16 cubic ly volume - so we could say 3.14^13 ish stars as an estimate. So I'd be guessing many more than 300 bn stars in the galaxy?

Google says 250 +/- 150 bn. I think low...

"... contains a representative sample of 1 percent of the Milky Way’s orbs ..."

You should probably read the page before commenting on the title alone...

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