# What if the rest of the universe disappeared? **URL:** \ **Category:** Factual Questions\ **Created:** [November 30, 2021, 2:47am UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178 "2021-11-30T02:47:13Z")\ **Posts on this page:** 6\ **Page:** 3
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [December 3, 2021, 5:27pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/41 "2021-12-03T17:27:11Z")
> [@Jasmine](#): > > Google and I have determined that the nearest star to us is 4.246 light years away, that’s 24.960.643.334.537 miles away. That’s the NEAREST star. I seriously doubt that our solar system would feel even a slight effect from the disappearance. True, our solar system circles our galaxy so, because of its disappearance, would no longer travel in any specific direction. Since our solar system is a closed system, however, it doesn’t really matter how it meanders around empty space. That’s kind of, basically, the source of the question. We know that earlier stars are the source of most of the matter in the planets, and that humans and other creatures depend on the stars to navigate and cosmic rays cause mutations, both good and bad. But now that we’ve evolved and are standing on billions of tons of higher elements that were formerly star stuff (in Carl Sagan’s famous phrase), what does the rest of the universe mean for us? ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [December 3, 2021, 5:27pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/42 "2021-12-03T17:27:58Z")
The Doctor Who episodes “The Pandorica Opens” and “The Big Bang” are about the destruction, and eventual restoration, of the entire universe other than the Earth, Moon and Sun. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 3, 2021, 5:36pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/43 "2021-12-03T17:36:40Z")
Ben Reich in Alfred Bester’s The Demolished Man had a rough night, when the stars, planets, Sun and Moon all disappeared. (Beverly Crusher replies “The same thing happened to me!”) ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [December 3, 2021, 7:47pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/44 "2021-12-03T19:47:55Z")
> [@Ike\_Witt](#): > > Eventually, after millions if not billions of years, we will not be able to see other galaxies. After enough time there will be nothing visible outside of our solar system. A consequence of universal expansion. This is only true of the universe on a large scale – i.e.- the more distant galaxies. It’s not true within any given galaxy like the Milky Way, which is held together by gravitation. It’s not even true with our Local Group of 20-some galaxies, where relative motion can still overwhelm the expansion of space. In fact the Andromeda Galaxy is rushing toward us at about 110 km/s (around 250,000 mph) and will collide with the Milky Way in about 4.5 billion years. > **[Andromeda–Milky Way collision](https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision)** > > The Andromeda–Milky Way collision is a galactic collision predicted to occur in about 4.5 billion years between the two largest galaxies in the Local Group—the Milky Way (which contains the Solar System and Earth) and the Andromeda Galaxy. The stars involved are sufficiently far apart that it is improbable that any of them will individually collide, though some stars will be ejected.\[self-published source\] > The Andromeda Galaxy is approaching the Milky Way at about 300 km/s (200 miles per second)... > [@Kedikat](#): > > But the velocity of a body in a straight line in a universe that contains nothing else? That befuddles me. I suppose it has added kinetic energy. But how can that ever be measured? Nothing to slam into. It has some relativistic effects? But again, there is nothing to measure it against. Such a body would, by definition, have zero velocity and zero kinetic energy. ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [December 3, 2021, 8:07pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/45 "2021-12-03T20:07:20Z")
I was basing my answer off of information, mainly from [this video](https://www.youtube.com/watch?v=gEyXTQ9do-c&t=803s). It is more likely than not that I mistook what he was saying. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 3, 2021, 10:38pm UTC](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178/46 "2021-12-03T22:38:14Z")
> [@wolfpup](#): > > In fact the Andromeda Galaxy is rushing toward us at about 110 km/s (around 250,000 mph) and will collide with the Milky Way in about 4.5 billion years. Don’t be too sure about this. It’s common to post that this is a fairly sure thing (and I’ll admit to having done so), but some recent research casts some doubt about it. Bad Astronomer column: > **[Uncertain future: Is Andromeda going to collide with the Milky Way or not?](https://www.syfy.com/syfy-wire/bad-astronomy-the-andromeda-galaxymilky-way-collision-is-now-in-doubt)** > > In 2012, astronomers announced a startling result: The had used Hubble to very carefully measure the motion of the Andromeda galaxy, and found that it appeared to heading very nearly directly toward the Milky Way at 100 kilometers per second. They... Anyway, we’ll have a much better idea of what the transverse velocity of Andromeda Galaxy is in 5 to 10 years. If it’s below about 50 km/sec, brace yourself for a head-on; if it’s over about 80 km/sec, relax, not going to happen. In between, the two may perform a do-si-do or two before tying the knot. [Previous page](https://boards.straightdope.com/t/what-if-the-rest-of-the-universe-disappeared/955178.md?page=2)