One of the Milky Way's arms might encircle the entire galaxy | Hacker News Reader

One of the Milky Way's arms might encircle the entire galaxy

phys.org

36 pointslelf21 comments

Not entirely related, but the scale of this I find just mind boggling. E.g. I learned a little while ago that the universe of Star Trek just takes place in "our" galaxy alone! Not the entire universe, just our galaxy. Imagine the billions of other galaxies out there... Mind blown..

Most of it (original and TNG) actually takes place in the 'alpha quadrant' only. DS9 introduces the wormhole to the gamma quadrant, and Voyager is mostly about the trek back from the delta. Warp 9 is garbage in the grand scheme of things eh! ;)

One of the exceptions being when ToS crossed the Galactic Barrier.

It took the Kelvans 200 years to get from Andromeda to the Milky way. It would have taken Voyager over 30 years to go the 30,000 light years from the Delta Quadrant.

Andromeda is about 2.5 Mly away, or over 80x the distance that Voyager would have had to travel. By this we can determine that the Kelvan ship was about 10x faster than Voyager.

I knew someone would catch me with the exceptions right after pressing reply. There's also the TNG episode with The Traveler, where the Enterprise is pushed 2.7 million lightyears out of the galaxy.

The Milky Way galaxy is approximately 100,000 light-years long and 1,000 light-years deep (Wikipedia). edit: I'm not sure why I felt the need to write that.

Voyager was 70,000 light-years from home and it was said on the show they needed 70 years at warp 9 to get home so the velocity of warp 9 must be 1,000 light-years per year (365 earth days) plus the whole faster than light thing which disregards the usual light year in a year thing. That's 2.74 light years per day which seems low considering Warp 1 is supposedly equivalent to the speed of light.

We've been lied to all these years it's all fake man!

What part of "2.74 light years per day" seems low? Assuming your break down to the day level is right, to expand, it means at warp 9 voyager is capable of covering a distance of 2.74 light years in 1 day. That means the distance that light could travel in 2.74 years, Voyager could cover in 1 day. So warp 9 = 2.74 x 365 x speed of light =~ 1000 times speed of light. So warp 1 = speed of light. warp 9 = 1000 times speed of light. which does not seem 'low' to me.

All you did was reverse the calculation that was done in the comment you are replying to. He already stated that warp 9 is 1000 times the speed of light:

"the velocity of warp 9 must be 1,000 light-years per year"

OP points out that warp 1 is supposedly speed of light and yet some how warp 9 being 1000 light years per year is somehow not impressive enough. I reversed the calculation to point out that warp 9 = 1000 times speed of light. And want to know what part of it is not impressive enough or misleading.

And by the way OP did not directly point out that warp 9 is 1000 times speed of light and my intention was to point that out to make sure they did not get confused by their own calculation which might have led to their underwhelming impression.

Seeing OP's response to one of the comments below (warp 9 factor = 834 ) validates my assumption that OP was lost in his own calculations for a moment. Only they can confirm.

Warp 9 is 834 times the speed of light

Source: http://en.memory-alpha.org/wiki/Warp_factor

I looked there but couldn't find it which I thought was odd. Thanks!

Here's something that recently blew my mind, there are stars in our universe that are larger than the width of our entire solar system. Space and objects inside it is huge!

What if I told you there are blackholes larger than our entire solar system?

"The diameter of the black hole's immense event horizon is on the order of 110 billion kilometres, 18 times the distance from the Sun to Pluto, and has the mass equivalent to that of two dwarf galaxies."

https://en.wikipedia.org/wiki/Phoenix_Cluster

http://youtu.be/QgNDao7m41M?t=2m40s

Blackholes I get because I've always considered them big and heard about the massive ones in the center of galaxies but stars felt different because I was used to the size of our Sun.

Not that the Sun isn't big, I just expected other stars to be relatively the same size, give or take a few orders of magnates. These things are so large http://www.kratosguide.com/wp-content/gallery/mind-pictures/...

Correct me if I'm wrong bu blackholes are compressed matter. They are typically formed by a star that collapses on itself, so they are always very small in comparison. That's why I couldn't believe it when I found out there were some so large. Unless... they become so large by eating worlds over time? Where are all the HN physicists when you need them?

I believe the singularity point, where all the mass collects, is small (dimensionless) but the gravity well that is created by the mass is what is measured when the size is determined. The edge of the gravity well is referred to as the event horizon. The event horizon of a black hole is the point which matter can no longer escape the gravity of the black hole.

However, I've been wrong several times already in this thread so take it for what that's worth.

Can't edit my original post but I need to correct myself. The largest known star is VY Canis Majoris which is about 6.6 Astronomical Units wide. Our solar system has a diameter of 79 AU. So stars are big but there doesn't seem to be a known star which is as big as our solar system, yet!

Here's another video that goes into the size of things. You can mute the sound, you're not missing anything https://www.youtube.com/watch?v=HEheh1BH34Q

It has a radius of 6.6AU, which means it actually has a diameter/width of 13.2AU.

Also there are a few stars which are candidates for "the largest star" which you can see at http://en.wikipedia.org/wiki/List_of_largest_known_stars. A few of them are larger than VY Canis Majoris.

Thanks for the corrections. Wish I could edit my original comment to note the inaccuracies.

I've still not found anyone who can explain to me why galaxies aren't simply considered large (and 3 dimensional) accretion discs. In that regard, why would it be weird that "arms" of the accretion disc might not wrap completely around the drainspout anyway?

I guess it's not romantic to think we're all just circling a very large drain...

If it's romantic you're looking for, forget about gravity for a minute and consider the large-scale electromagnetic forces at work. The recent news about intergalactic structures in the universe (google "the great attractor" to start), our position on the edge of Laniakea and the seemingly-mirrored Perseus-Pisces supercluster, of which we are basically smack dab in the middle. Obviously not definitive by any stretch, but maybe we actually are the center of it all?

Spiral arms would be dispersed too quickly by the orbital speeds' varying with radial distance. Some process needs to be maintaining them. http://en.wikipedia.org/wiki/Spiral_galaxy#Origin_of_the_spi...

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