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

spacetelescope.org

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

#41

Post by tome »

dom96 wrote: post #31
saiya-jin wrote: post #17

Earlier quoted context omitted.

mankind has been extremely lucky with our environments, among others: - Jupiter & Saturn pick out most of the comets, so we encounter massive reset only very rarely - thanx to hitting other planet long time ago, we have a spinning molten metal core inside planet generating magnetic shield for all nasty radiation - moon gives us tides & stability - our sun is just the right size and age to be stable - we're located at…

You're assuming that all life will be like ours. This is a safe bet, but there could be very many ways for life to exist.

Can you suggest another one?

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

#42

Post by Razengan »

millstone wrote: post #15
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…

Me, I think there is no life beyond Earth. > How, when given the evidence of practically infinite planets out there (considering that almost every star may have at least one planet, and there are even rogue planets [0] that don't orbit any star, and that asteroids and comets or even dense nebulas could also harbor life), can we even consider the possibility that this is the only planet with life? Who gives a shit? If…

> If our spaceships landed on a distant planet populated by a vast hyper-intelligent civilization of decidedly not-alive robots, would we shrug, say "no life here," and head home bored?

As a different take on that: Suppose we develop "robots" that can sustain themselves, mine resources, produce [ever improving] copies of themselves, and learn on their own and teach each other. Then we send them to colonize a distant planet.

Fast forward a hundred years. Those robots now have a "civilization" of their own.

By what criteria would that civilization fail to be counted as "life" by an species looking for such?

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

#43

Post by zimpenfish »

SideburnsOfDoom wrote: post #39
inventingwithmo wrote: post #10

Earlier quoted context omitted.

I realise I'm arguing against a work of comedy, but: > But not all of them are populated; therefore only a finite number are. There are infinities of different sizes

My understanding is that the infinity of "all integers greater than zero" and of "all integers greater than zero and divisible by 2" are in fact infinities of the _same_ size. The same would apply for "divisible by 100" or "divisible by 1 million". This would apply to the fraction of worlds that are populated, whatever fraction of them are.

As best I understand it, all those reduce to aleph-zero because they're countably infinite and can be mapped to the natural numbers. But aleph-one exists and is provably bigger than aleph-zero despite both being infinite.

https://en.wikipedia.org/wiki/Aleph_number http://www.alephzero.co.uk/what.htm

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

#44

Post by V-2 »

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…

> 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 get down to 1.

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. (At a given point in time, that is - that's another aspect of course).

Or 12 factors, but each with a 1% chance. And suddenly it doesn't seem like a number big enough to warrant certainty claims...

Basically it is the "wheat and chessboard" problem in reverse.

You start with a huge pile of planets, but once you start splitting the pile, it shrinks very very fast.

Personally I'm not sure either way, and I think being sure (either way) is just naive.

I believe there is microbial life out there, and I accept a slim chance we may actually discover it - say, over the course of the next few centuries - but I'm sceptical about the existence of intelligent life, and even if it did exist, I see the chances of any contact to ever occur as zero.

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

#45

Post by Razengan »

V-2 wrote: post #44
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…

> 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.

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

#46

Post by im3w1l »

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.

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

#47

Post by Razengan »

tome wrote: post #41
dom96 wrote: post #31

Earlier quoted context omitted.

You're assuming that all life will be like ours. This is a safe bet, but there could be very many ways for life to exist.

Can you suggest another one?

• Robots that perform all the functions humans do, including making copies of themselves and teaching each other.

• Hive-mind species where there are no individuals.

• Species without any gender or sexual reproduction, whose individuals are spontaneously "born" in specific locations and conditions on their planet.

• "Species" consisting of a single, massive/long-lived individual.

• Parasitic intelligences that "infect" various other, unrelated species and direct them towards the goals of the parasites.

• Lifeforms floating around in gas giants or even in nebulas.

• Life-bearing planets themselves being a lifeform; that "reproduces" when the civilizations it supported upon itself go on to terraform other planets to become like their home planet.

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

#48

Post by kamaal »

hanbura wrote: post #26
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…

>I also doubt humanity will find a way to travel fast enough to get to another solar system within a human lifespan. The next solar system is only four lightyears away. Given the will to break nuclear test ban treaties we think we could develop nuclear pulse propulsion drives that achieve about 10% the speed of light. Even after accounting for acceleration and deceleration that gets us there in a human lifespan. Gran…

A better strategy is to start mining asteroids. Sell mined stuff on earth to make enough money to build ships and lift necessary bootstrapping material out of the gravity well.

Also plenty of water out there and sunshine, burning hydrogen as fuel should be possible.

Now you will have enough machinery in space to mine building stuff and enough fuel. Gradually build permanent colonies in space.

It won't get all humans out of earth soon or ever. But it will put some humans permanently out of earth. Then keep building colonies as population in space grows.

Once you have done this you have done two things:

1. Eliminate a existential threat to humanity more or less permanently.

2. A slow but steadily growing population of humans in space.

Several decades/centuries after that you could have humans permanently living and working in space. From there its a matter of population growth, resources are a plenty and you have a universe for the taking.

Once you have a massive presence in space interstellar travel by definition is a question of acquiring real estate to keep up with population growth.

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

#49

Post by andyjohnson0 »

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 telescope sensitivity, but which are nevertheless theoretically observable.

It might be useful to describe the detectable part of the observable universe as the "visible universe", but astronomers have a different meaning for that. See https://en.wikipedia.org/wiki/Observable_universe.

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

#50

Post by FreeHugs »

V-2 wrote: post #44
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…

> 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?
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