Observable Universe contains 10x more galaxies than previously thought (2016) • Hacker News Board

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#71

Post by Scarblac » Thu, Jan 04, 2018, 1:41 PM UTC

Razengan wrote: post #45

V-2 wrote: post #44

Earlier quoted context omitted.

> How, when given the evidence of practically infinite planets out there [...] can we even consider the possibility that this is the only planet with life? Human minds aren't good with very large numbers. What seems "practically infinite" to us - isn't, really. The number of all planets in the universe is said to be in the ballpark of 10^24. Meaning (obviously) if you keep on dividing it by 10, in just 24 steps you g…

We don't know all the factors under which life can exist. Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes. We even have evidence of life we have never seen, will never encounter, and may never even have conceived as being possible to exist without that evidence: the enormous dinosaurs.

> Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes.

But all lifeforms we know evolved from one common ancestor, it's one tree of life. As far as we know life evolved here only once.

So we know that once life happens it can become completely ubiquitous, but it doesn't say anything about that crucial first step.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#72

Post by almavi » Thu, Jan 04, 2018, 1:50 PM UTC

im3w1l wrote: post #46

almavi wrote: post #12

I don't understand. They say the observable universe contains 10x more galaxies than previously thought, and the reason for that is the concentration of galaxies being greater in the part of the universe that our telescopes can't see?

"observable universe" is a technical term for the part of the universe from which light has had enough time to travel to us. It doesn't mean we can literally observe it using current tech.

Ok, I was missing the technical definition. Thank you very much!

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#73

Post by almavi » Thu, Jan 04, 2018, 1:50 PM UTC

andyjohnson0 wrote: post #49

almavi wrote: post #12

I don't understand. They say the observable universe contains 10x more galaxies than previously thought, and the reason for that is the concentration of galaxies being greater in the part of the universe that our telescopes can't see?

The Observable Universe is the part of the total universe that we can theoretically observe because electromagnetic radiation from it has had time to reach us. In practice, some of this radiation will be detectable with current technology and some of it will be too faint. The article is about work, using models of galaxy formation, that tries to better estimate the number of galaxies we can't detect due to limits on…

Yeah, I understand this now, thanks.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#74

Post by sudhirj » Thu, Jan 04, 2018, 1:56 PM UTC

Razengan wrote: post #3

And some people still aren’t sure if there is other life beyond Earth. :) That's entire galaxies. Not just stars, and that's just the observable universe. We are still being surprised by the lifeforms we observe here on Earth, and the environments and conditions they can thrive in (including the outer hulls of our spacecraft), and we still have yet to discover and catalog all the life on our planet. Life may even com…

Any estimations about life outside Earth only become viable once we understand the factors that gave rise to it first, and their probabilities of occurrence. If the total probability is less than 10^24 (say) we might expect life elsewhere, but if it's 10^100 probably not. But either way, gut feel and intuition about this are pointless - by the anthropic principle, we're speculating about the possibilities of life only because we're already winners of the lottery - almost like someone lucky enough to win a lottery twice or thrice in a row wondering why it doesn't happen to everybody.

Either way, I actually think that the Dark Forest principle applies heavily in the universe (https://en.wikipedia.org/wiki/The_Dark_Forest) - no halfway intelligent civilization should assume the intentions of any other civilization are benign until proven to be so, and will always take steps to either hide themselves or shoot first and investigate later.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#75

Post by laumars » Thu, Jan 04, 2018, 1:57 PM UTC

millstone wrote: post #33

laumars wrote: post #18

Earlier quoted context omitted.

One could flip your argument and say defining life as purely organic is a failure of imagination. The thing about searching for "life" over "intelligence" is that life doesn't necessarily need to be intelligent for it to be interesting. I also think the SETI example you've made is a tad unfair because their process dictates that their search be for intelligence (crudely put, radio transmissions). Whereas when you're…

> One could flip your argument and say defining life as purely organic is a failure of imagination. That's right! So how would you define life? Or the meta-question, why bother? We gain nothing from figuring out what's "alive" and what has "merely" a rich complexity. "Search for life" is a category error. > The thing about searching for "life" over "intelligence" is that life doesn't necessarily need to be intelligen…

> That's right! So how would you define life? Or the meta-question, why bother? We gain nothing from figuring out what's "alive" and what has "merely" a rich complexity.

> "Search for life" is a category error.

To be honest I think you're over thinking the whole "life" thing. It's just a label. You could replace that term and still have the same arguments. eg "What would someone define as 'interesting'? What does that category even mean?". Or "complex", or "intelligent" or any other label.

> Why hope to find life, when we know life is already possible?

Possible, yeah. But it's unique in that we are constantly finding a multitude of other phenomena in the universe yet we've only ever observed life on our own planet. That alone makes this topic interesting in my opinion.

I don't see why it has to be an either / or though. Nobody is suggesting we search for life at the sacrifice of learning more about black holes...or whatever.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#76

Post by sudhirj » Thu, Jan 04, 2018, 1:58 PM UTC

ageofwant wrote: post #68

Cthulhu_ wrote: post #22

Earlier quoted context omitted.

> And some people still aren’t sure if there is other life beyond Earth. :) Until we actually observe it, no, we can't be sure; the probability of it existing is high simply due to the sheer amount of dice rolls there are in the universe, but the likelihood of us observing it is low. We already know there is and was no intelligent life in our solar system besides what's on Earth; there's still hopes of finding traces…

We already have that technology, more or less... A orion type drive is can be built using 1960's technology, the rest is just engineering, not new physics. A orion type drive can take you as close to c as you can afford. At 0.9999999c you can travel to A.Centauri in 1/2 day. Granted getting to 0.9999999 and back again is gonna take a fair pile of h-bombs.

Just to be clear, that would be 1/2 day for the people on the spacecraft. For the people you leave behind on earth you'd still be gone 4 years each way.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#77

Post by Retric » Thu, Jan 04, 2018, 1:58 PM UTC

Scarblac wrote: post #71

Razengan wrote: post #45

Earlier quoted context omitted.

We don't know all the factors under which life can exist. Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes. We even have evidence of life we have never seen, will never encounter, and may never even have conceived as being possible to exist without that evidence: the enormous dinosaurs.

> Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes. But all lifeforms we know evolved from one common ancestor, it's one tree of life. As far as we know life evolved here only once. So we know that once life happens it can become completely ubiquitous, but it doesn't say anything about that crucial first step.

> But all lifeforms

That's not nessisarily true. Single celled organisms have a rather fluid exchange of genetic information even our 'single cells' are really several different organisms. It's possible life evolved many times on earth and current single celled organisms and thus all life has a mismatch of ancestors.

Further, life may regularly evolve even today, but simply get eaten due to the stiff competition.

PS: We know life evolved at least once, but the high end could be multiple times a second on earth.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#78

Post by monktastic1 » Thu, Jan 04, 2018, 2:17 PM UTC

FreeHugs wrote: post #50

V-2 wrote: post #44

Earlier quoted context omitted.

> How, when given the evidence of practically infinite planets out there [...] can we even consider the possibility that this is the only planet with life? Human minds aren't good with very large numbers. What seems "practically infinite" to us - isn't, really. The number of all planets in the universe is said to be in the ballpark of 10^24. Meaning (obviously) if you keep on dividing it by 10, in just 24 steps you g…

Meaning if there are 24 factors crucial for life to evolve, and each has a 10% chance of occurring - it's actually quite likely only one planet would win on this lottery. Is it? What is the probability?

Phrased differently: the expected number of such planets is 1.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#79

Post by elorant » Thu, Jan 04, 2018, 2:35 PM UTC

Razengan wrote: post #3

And some people still aren’t sure if there is other life beyond Earth. :) That's entire galaxies. Not just stars, and that's just the observable universe. We are still being surprised by the lifeforms we observe here on Earth, and the environments and conditions they can thrive in (including the outer hulls of our spacecraft), and we still have yet to discover and catalog all the life on our planet. Life may even com…

Until a flying saucer lands on my yard I have to assume there is no life in Universe.

Re: Observable Universe contains 10x more galaxies than previously thought (2016)

#80

Post by Pigo » Thu, Jan 04, 2018, 2:35 PM UTC

Cthulhu_ wrote: post #22

Razengan wrote: post #3

And some people still aren’t sure if there is other life beyond Earth. :) That's entire galaxies. Not just stars, and that's just the observable universe. We are still being surprised by the lifeforms we observe here on Earth, and the environments and conditions they can thrive in (including the outer hulls of our spacecraft), and we still have yet to discover and catalog all the life on our planet. Life may even com…

> And some people still aren’t sure if there is other life beyond Earth. :) Until we actually observe it, no, we can't be sure; the probability of it existing is high simply due to the sheer amount of dice rolls there are in the universe, but the likelihood of us observing it is low. We already know there is and was no intelligent life in our solar system besides what's on Earth; there's still hopes of finding traces…

That was my reaction as well. If you're being scientific about it, how can you be sure at all? We have observed exactly zero instances of life beyond Earth. We're all free to believe whatever we like. I have beliefs of my own, but I don't expect anyone to share them unless they happen to believe it too. I just hope people who are so sure of extraterrestrial life can comes to terms with the fact that they are making a leap of faith.