There are 10 times more galaxies in our universe than we'd estimated - Page 1
Forum section: electronics / general

author: Homer J Simpson
author_rank: Super Contributor
timestamp: October 13, 2016, 11:45:50 pm
content: http://www.cnn.com/2016/10/13/health/hubble-telescope-galaxies-trnd/index.html

author: Homer J Simpson
author_rank: Super Contributor
timestamp: October 14, 2016, 12:17:53 am
content: 2 trillion galaxies.How many solar systems? How many habitable planets? Probably quite a big number.How many with advanced civilizations? Probable quite a few. No way we are it.Need to get out Drakes Equation.

author: Brumby
author_rank: Unknown
timestamp: October 14, 2016, 01:15:48 am
content: "Thereare10 times more galaxies in our universe than we'd estimated"Rather definitive.I would think it really means:"It is estimated that there are 10 times more galaxies in our universe than we'd estimated"

author: sony mavica
author_rank: Frequent Contributor
timestamp: October 14, 2016, 01:16:45 am
content: interesting

author: ez24
author_rank: Super Contributor
timestamp: October 14, 2016, 01:29:39 am
content: We cannot count them because our brains have limited cells and there are infinite galaxies.

author: Brumby
author_rank: Unknown
timestamp: October 14, 2016, 01:39:33 am
content: Our limited brain cells can cope with a trillion just fine, thank you very much.Even if that number is out by a factor of a trillion, there's no real difficulty..... and even ifthatnumber was out by a factor of a trillion, we could still write it down in a few seconds.In fact, comprehending the number side of this topic is not a problem at all.Contemplating the physical distribution, however, is quite another thing.

author: Syntax_Error
author_rank: Regular Contributor
timestamp: October 14, 2016, 01:40:08 am
content: Disclaimer: I am barely even a meager lay person when it comes to this topic, so my very question may be "incorrect". Please answer what I mean, not what I say.Question: Currently, popular science (not the magazine) cites an apparent discrepancy between the observed matter in the universe and the strength of the gravitational field as background (I won't claim it as evidence) for the existence of dark matter. In light of this discovery, is it possible or likely that perhaps we just haven't yet observed all the required "ordinary" matter to account for the measured gravity attributed to this equivalent mass?This would seem to make much more intuitive sense in my lay person's brain than invocations of dark matter and dark energy, etc. Mostly because I am unscientific and don't want it to exist, preferring a simpler answer.

author: Brumby
author_rank: Unknown
timestamp: October 14, 2016, 03:29:14 am
content: I believe I understand your question ... and I believe the answer to it is this:The amount of visible matter within our field of view is not sufficient to explain the gravitational effects we can see within that field of view. We need more matterwithin that field of viewto explain those effects. Since we can't see that matter directly, it has been given the moniker 'dark matter'.Yes, there might be more matter outside our field of view - but it is in thewrong placeto produce the effects we see.

author: Brumby
author_rank: Unknown
timestamp: October 14, 2016, 03:39:02 am
content: As a simple example, let's take the Earth and the Moon.Sitting above our solar system, we can look down and see the Earth orbiting around the Sun, and the moon orbiting around the Earth. If we look at the path the moon takes around the Sun, we can safely say there is an object of a reasonable mass that the Moon is orbiting around and that both the Moon and that object (the Earth) are orbiting the Sun as a two-part system.Now, let's make the Earth out of an equivalent mass of Dark Matter.We can't see the Earth any more - but we know there has to be something there to explain the Moon's path. If we were to take the Earth and stick it outside the solar system, the gravitational effects would be vastly different - and it just wouldn't give the observed result.

author: Syntax_Error
author_rank: Regular Contributor
timestamp: October 14, 2016, 03:44:46 am
content: Quote from: Brumby on October 14, 2016, 03:29:14 amFascinating....and weird at the same time. Thanks for the insight. What you say makes sense, it is just so weird to imagine enough mass "out there" that doesn't interact with electromagnetic force so as to not be detectable with conventional means....I don't like it. Much in the same way the ancients tried to decree pi to equal to 3.0. They knew it wasn't correct, that the observations were correct, but they were inconvenient at the time.

author: Brumby
author_rank: Unknown
timestamp: October 14, 2016, 04:00:26 am
content: Quote from: Syntax_Error on October 14, 2016, 01:40:08 amThat's understandable - but the Universe is not so obliging.Human understanding has evolved (sometimes quite dramatically) and at each step into a new realm comes with it the casting off of old beliefs. This was often unsettling - as we had grown up with these beliefs and the new ones didn't make sense and just felt 'wrong'.My favourite head spin comes from Quantum Physics. That is really counter-intuitive - until you start thinking about all the weird stuff as fact. Even then it's a challenge ... but you can't deny it is real. It just works - a fact that semiconductors have relied upon for decades.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 14, 2016, 06:33:49 am
content: Quote from: ez24 on October 14, 2016, 01:29:39 amNo infinities.Never.When scientists speak ofThe Universe, they almost always are speaking of theVisible Universe. Which is some 13.8 billion years old (chronologically), and some 50-ish billion light years across (by proper time -- the width, at "present time", can be greater than the light-time age of the universe, because the fabric of the universe itself has expanded -- at the edges which are visible, it has since expanded away, faster than the speed of light. That's why stuff on the edge appears so extraordinarily old and distant.) Objects are not allowed to go faster, but the stretching of space itself can go at any speed it may. Remember, the Alcubierre drive is theoretically consistent, too.)The whole Universe, including that outside thevisible, is (as far as we can tell) infinite. Or, there's no reason (as yet) to believe that it has any obvious extents, so it's as good as infinite.It's very, very likely that there exists a uniform distribution of galaxies, outside of our visible horizon (beyond the visible universe). We just can't see it, except through tenuously inferred relationships (i.e., how the oldest galaxies, and CMB, have apparently been tugged around by consequent assumed mass distributions).Tim