Slashdot Mirror
The Universe Has 20 Times More Galaxies Than We Thought (gizmodo.com)
A new study by a team of international astronomers has produced some astounding results: they concluded that the universe contains at least two trillion galaxies -- as much as 20 times more than previously thought. The study adds that 90 percent of all galaxies are hidden from us. This hidden portion can't be seen even with our most powerful telescopes. Gizmodo adds: Consequently, this means we also have to update the number of stars in the observable universe, which now numbers around 700 sextillion (that's a 7 with 23 zeros behind it, or 700 thousand billion billion). And that's just within the observable universe. Because the cosmos emerged some 13.8 billion years ago, we're only able to observe objects up to a certain distance from Earth. Anything outside this "Hubble Bubble" is invisible to us because the light from these distant objects simply haven't had enough time to reach us. It's difficult -- if not impossible -- to know how many galaxies reside outside this cosmological blind spot.
It's very probable. But since we also know that the Periodic Table of Elements is universal, as well as the fundamental forces, we also know things like warp drive are just not feasible...
So they are over there, and we are here. End of story.
as far as I can tell it doesn't matter - dark matter is invoked to explain why individual galaxies don't fall apart, because the mass we can see doesn't seem to be enough to keep it together at the rate they spin; having more galaxies doesn't change that.
(I find it amusing that dark matter is handwaving why big things don't fly apart and dark energy is handwaving why bigger things do :) But I'm weird :)
The speed of light limits how fast you can travel through space. The expansion of the universe is due to space itself expanding, and there is no limit (as far as we know) to how fast this can happen.
Only crack the nuts that crack. You don't put the ones that don't crack in the sack.
So I had to click around awhile, but here's the actual paper:
http://www.spacetelescope.org/...
For some of us, it makes a huge difference if we're reading the actual paper, or trying to understand the watered-down version on a click-bait site.
The Drake Equation just deals with our galaxy, so it doesn't have any effect.
I believe it was limited as such because it would be "more feasible" to have a meaningful conversation with a species in this galaxy thanks to the distances involved.
The presence of dark matter is inferred from the behavior of individual galaxies. The gravitational binding energy of galaxies should be much higher than what we can attribute to baryonic matter alone. So even though there are more galaxies than we thought, they still require dark matter to account for this discrepancy.
Basically, if we assume that 20x the number of galaxies means 20x the amount of baryonic matter (which not necessarily true, but whatever), then there must be 20x the amount of dark matter as well. So the ratio of baryonic matter to dark matter would remain the same.
Only crack the nuts that crack. You don't put the ones that don't crack in the sack.
That has blown my mind.
What about dark matter ? Does anyone know how that figures into this ?
It doesn't.
Dark matter is used to explain the rotation rates of galaxies (there isn't enough visible matter to account for those rates.)
This study says we have more galaxies than we thought, not more stars within them than we thought.
If it weren't for deadlines, nothing would be late.
It doesn't. The Drake equation only applies to the Milky Way. If you want to expand the Drake equation to the entirety of the universe, you take whatever number you get from the Drake equation, and multiply by the number of galaxies in the universe, which keeps being revised upwards with more detection. So at minimum, you are looking at whatever your Drake equation is times a hundred billion.
well, it's 121 years, but according to this article on Lord Kelvin, he said something like that (not exact - but exactness was not specified). I'm inclined to give him the year.
(I find it amusing that dark matter is handwaving why big things don't fly apart and dark energy is handwaving why bigger things do :) But I'm weird :)
Galactic rotation curves was just the first bit of observational evidence that we saw over 80 years ago. Since then, every other explaination has been shown not to be the case. Since then, there have been many other observed evidence such as gravitational lensing, fluctuations in the CBR, etc. which is all under Observational Evidence under the Dark Matter Wikipedia page. All have been pointing more and more towards matter than only interacts via gravity, while all other competing theories fail to explain other observations. Furthermore, it tends to be called dark matter, and dark energy, energy, because they end up with unknowns that have specific units, and when those units are those of mass or energy, they get called mass and energy.