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Hubble Finds 10 Times More Galaxies Than Thought
- ciphre 10y agoSo, instead of 200 billion galaxies, the number would be closer to 2 trillion galaxies. I thought the first number seemed like a lot, wow. I wonder how many stars there are if that is the case. At 100 billion stars per galaxy, the number would be 2×10²³ stars. I believe that's 2000 billion trillion.
- yummybear 10y agoMultiply that with about 5-10 for planets. Mindboggling.
- sp332 10y ago5-10 planets per star seems a little high.
- Esau 10y agoReally? Considering how many bodies orbit our Sun, I would have thought 5-10 would be a good average.
- mortenjorck 10y agoThis Quora answer (https://www.quora.com/What-is-the-average-number-of-planets-per-star https://www.quora.com/What-is-the-average-number-of-planets-...) takes a dataset of 2560 stars and comes out with an average of 1.3 planets per star. As the author caveats, this is an extremely small sample and probably not accurate, but it's something to start from.
- _red 10y agoCaveat+: No one yet knows if we can even reliably count the planets of a distant star, so the figures could be off by some significant amount. Caveat++: That light reaching earth from far away galaxies was then, this is now.
- flukus 10y agoCaveat+++: We're also interested in moons, which I don't think have been detected yet.
- Razengan 10y agoCaveat++++: Factor in rogue planets that don't orbit any stars, or large asteroids drifting through nebulas etc... I'm sure the number of solid bodies — potential habitats for life or artificial constructs — in our universe is magnitudes larger than the number of stars we've detected, and the latter is already a mind boggling quantity.
- Esau 10y agoThanks.
- BurningFrog 10y agoThe way we detect planets only detect some of them. The best method is to notice when a planet passes in front of its star, by how it gets slightly dimmer. That only works if its orbit happens to be directly between us and that star.
- aruss 10y agoWe can also detect them by a Doppler shift of the star, because the planet (if big enough) will move the star as it orbits. This works when the transit method fails, but provides fewer data on the planet itself.
- SAI_Peregrinus 10y ago
- MPSimmons 10y agoI would tend to agree. The effective gravitational influence of a star would be relative to its mass. We can pretty easily determine the (rough) mass of a star, and ours appears(?) to be somewhere in the middle, so it stands to reason that 8-ish decently sized planets is not an unreasonable number.
- onion2k 10y agoExtrapolating from a single example? There's an XKCD for that: https://xkcd.com/605/ https://xkcd.com/605/
- pmoriarty 10y agoThen figure in the dwarf planets, asteroids, and comets, and we'll start to get to some big numbers.
- lisivka 10y agoAnd don't forget about invisible «almost stars», Jupiter like systems, which outnumbers visible stars (IMHO), with their own planets (satelites?) and asteroids.
- vixen99 10y agoAlmost Avogadro's number - i.e., number of water molecules in a small cup of water (18ml/0.6oz).
- Retric 10y ago8oz = small cup. 0.6 oz ~= table spoon (15ml)
- deleted 10y ago[deleted]
- kijin 10y ago2 trillion times 100 billion is 200 billion trillion. Your scientific notation is correct, though.
- KnightOfWords 10y agoThat doesn't hold I'm afraid. The newly discovered galaxies are small and dim, so won't change the numbers very significantly. It's not as radical a discovery as it appear at first glance.
- deleted 10y ago[deleted]
- WalterBright 10y agoHubble has been so incredibly productive, if I had mega-billions I'd fund the construction and launch of several more of them.
- melling 10y agoIf...the biggest two letter word in the English language. Given how little we actually spend on this sort of stuff, I'd be happy if we could save Hubble, rather than let it retired and reenter the atmosphere and burn. Perhaps a robotic mission to repair it in 2025 can be added to our big plans to go to Mars, etc.
- WalterBright 10y agoGiven that probably most of the cost of the Hubble is R+D, another one could be built and launched for only a fraction of the cost of the original. 3 or 4, even lesser.
- laxd 10y agoOnly two years until James Webb telescope launches. Should keep us entertained for while.
- pmoriarty 10y agoI like this size comparison: https://upload.wikimedia.org/wikipedia/commons/4/42/JWST-HST-primary-mirrors.svg https://upload.wikimedia.org/wikipedia/commons/4/42/JWST-HST...
- jessriedel 10y agoNote that Webb is an IR telescope, which is longer wavelength, so the resolution actually is comparable to Hubble.
- jm547ster 10y agoDoes it offer any advantages to Hubble?
- danbruc 10y agoDoes this have any implications for the amount of dark matter or do estimates of the energy content of the universe not rely on the number of observed galaxies? If the number of observed galaxies does not matter, how do we account for this factor of ten? Galaxies are probably not ten times lighter - ignoring dark matter - than previously believed. Are those missing galaxies just very light? Is the universe heavier than previously assumed? How does that change the expansions of the universe? Does there have to be even more dark energy to compensate for this additional baryonic matter to match observed expansion rates?
- m4dc4pXXX 10y agoAlso questions I'd like to know the answers to!
- danbruc 10y agoMy layman guesses. The ratio of baryonic and dark matter remains unchanged because the new galaxies come with their own dark matter and we can determine the ratio from looking at individual galaxies. The amount of baryonic and dark matter in the universe goes up by a factor of ten unless the new galaxies are exceptionally small or large which would change this factor accordingly. Finally the amount of dark energy goes up to yield the observed expansion rate, no idea if that also means a factor of ten in which case the relative composition of the universe would remain unchanged.
- yummybear 10y agoMy understanding is that dark matter was "discovered" when trying to find out why stars in the outer edge of a galaxy rotates with the same speed as the inner. A ten-fold increase in number of galaxies doesn't seem to affect this.
- netcraft 10y agoI don't think our evidence for dark matter comes from interactions between galaxies but within a galaxy - the interaction of matter within the galaxy and the amount of lensing observed because of the amount of observed matter in a galaxy - in other words I dont _think_ that this will do much to the dark matter calculations - but I am not certain and hope someone knowledgeable will come along and set us straight.
- stephengillie 10y agoIf the universe is infinite, then aren't there infinite galaxies within it?
- eatporktoo 10y agoIf it is infinite then yes. We don't know that the universe is infinite.
- danbruc 10y agoThe number of galaxies is always for the observable universe - about 92 billion light years in diameter if I remember correctly - not the entire universe. From the observed flatness of the observable universe we know that the entire universe is at least about 100 times larger in volume assuming it is isotropic.
- daveloyall 10y agoWhat defines the horizon? Is the horizon spherical?
- AnimalMuppet 10y ago> What defines the horizon? The speed of light. Things beyond the horizon are things where the light hasn't had time to reach us yet. > Is the horizon spherical? Given that the speed of light is isotropic, yes.
- thaumasiotes 10y ago>> What defines the horizon? > The speed of light. Things beyond the horizon are things where the light hasn't had time to reach us yet. No. Things within the horizon are things where the light hasn't had time to reach us yet. Things beyond the horizon are things where no amount of time will ever enable the light to reach us. That's what makes it "unobservable".
- 10y ago
- daveloyall 10y agoRegarding Olbers' paradox, the explanation that the article gives contradicts what I heard elsewhere... I heard that the nighttime sky is dark simply because the universe is to young for the whole thing to get filled with light, though that will happen eventually. Crap, I can't remember where I read that. Somewhere linked off of HN. Nautil.us?
- danbruc 10y agoThis will not happen, the accelerating expansion of the universe will make more and more galaxies end up behind the horizon of our observable universe even though the horizon itself keeps expanding.
- pmoriarty 10y agoIt would happen if there's a big crunch. Also, a lot of astronomy goes on the assumption that the laws of physics are the same far away as they are near by, and that they don't change over time. It's possible that if either of these two assumptions are incorrect that anything goes. I'm also reminded of Arthur C. Clarke's famous dictum that, "when a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
- danbruc 10y agoBut the expansion of the universe is accelerating which tells us we are not in a big crunch scenario. And we have probed the laws of physics over very long distances and far into the past by looking at very distant objects and have to date not found any strong evidence for varying laws of physics over space or time. There are for example some claims of variations in the fine structure constant but as far as I can tell those claimed variations may still be explained by experimental errors and are therefore not widely accepted.
- Rzah 10y agoIf space is curved rather than flat we could still have a big crunch on the far side.
- lohankin 10y agoCan it be that in 10 years, everybody will believe that we live in simulated reality, and these galaxies are created on demand when we stare into particular region of space? Elon Musk says he thinks so: http://motherboard.vice.com/read/elon-musk-simulated-universe-hypothesis http://motherboard.vice.com/read/elon-musk-simulated-univers...
- duaneb 10y agoWhat's the point about asking untestable questions? You might as well become a theoretical physicist or a priest.
- smac8 10y agoBecause they are interesting and fun to think about? Because they may create new ideas which impact models, frameworks, directions, and analogies of thought in experimental and theoretical disciplines of the same or differing subjects? Because not everything is testable, or even when it is the number of variables simply makes controlling the experiment for accurate causal derivations difficult to impossible? (increasingly true as science progresses, often leading to false levels of confidence). Hmm......
- duaneb 10y ago> Because they may create new ideas which impact models, frameworks, directions, and analogies of thought in experimental and theoretical disciplines of the same or differing subjects? How do you figure? Whether we are in a simulation is a) unknowable by definition, or it's not a very good simulation, and b) doesn't change anything about how our universe works from our perspective. Why would speculation about "why" impact anything about the decisions we make?
- pmoriarty 10y agoIf someone thought they were in a simulation, they might try to find a way out of it, or might start not taking life seriously. If, as most people, you think that one's beliefs shape one's actions, then it should be pretty clear that a belief that we live in a simulation could lead to some people acting differently based on that belief. Only if one did not have free will or if one's beliefs did not shape one's actions would such a belief have no potential impact.
- hawski 10y agoWould that information extend our current estimation of heat death of the universe?
- platz 10y agodoes this also affect the friedman equation?
- michaelmachine 10y agoThere are also galaxies that are 99.9% dark matter apparently [1]. I don't think they are counted in this survey. [1]: http://www.skyatnightmagazine.com/news/galaxy-found-9999-dark-matter http://www.skyatnightmagazine.com/news/galaxy-found-9999-dar...
- andersonsantos 10y agoElon Musk is right, we do live inside a computer simulation. After spending a considerable amount of time analyzing the galaxies images used on this NASA article I'm comfortable to assure you, those galaxies are a computer's desktop wallpaper.
- Pigo 10y agoThis reminds me of the first time I seen Saturn through a powerful telescope. It looks cartoon-ish, or like a painting, even when you're not viewing it through some kind of media. It felt oddly synthetic.
- achr2 10y agoI have wondered for a while how we can be certain that looking so deeply into the distant (meaning past) universe gives an accurate picture. Wouldn't there be many compounding effects, such as gravitational lensing combined with expansion, that could be showing us a very different picture than the true structure of the universe?
- verytrivial 10y agoNitpick: It is more "Hubble data postulates existence of 10 x technically observable galaxies based upon their massive distance and hence age, and the rate at which galaxies eat each other over time."
- heldrida 10y agoQA finds 10 times more bugs than thought.