Gaia spots stars flying between galaxies • Hacker News Board

Re: Gaia spots stars flying between galaxies

#51

Post by TeMPOraL » Wed, Oct 03, 2018, 6:11 AM UTC

hyperpallium wrote: post #45

TeMPOraL wrote: post #5

Earlier quoted context omitted.

I have this science fiction writing/game backstory idea I recently came up with. Feel free to use it, as I guess I won't get around to do anything with it any time soon. Copying straight from my "ideas" file: At some point in time (past or future, or magically also present), a star passed in very close vicinity to our sun. It had a habitable planet in its system, full of alien plant and animal life. For the brief mom…

Pedantically, wouldn't Δv-accessible mean it would take a long time to get here, and we'd see it coming for a very long time? Possibly easy to address... maybe, it was small and dim, and in line with a bright star, so we'd interpreted it wrongly.

It would. I'd assume humanity knew about it for decades before it became "reachable" - preparing a colony ship (and creating a necessary infrastructure) would take many, many years. There's also a story to be found in the two planets being in radio range for a hundred years past leaving travel range.

Re: Gaia spots stars flying between galaxies

#52

Post by hyperpallium » Wed, Oct 03, 2018, 9:29 AM UTC

TeMPOraL wrote: post #51

hyperpallium wrote: post #45

Earlier quoted context omitted.

Pedantically, wouldn't Δv-accessible mean it would take a long time to get here, and we'd see it coming for a very long time? Possibly easy to address... maybe, it was small and dim, and in line with a bright star, so we'd interpreted it wrongly.

It would. I'd assume humanity knew about it for decades before it became "reachable" - preparing a colony ship (and creating a necessary infrastructure) would take many, many years. There's also a story to be found in the two planets being in radio range for a hundred years past leaving travel range.

I was thinking more of a scale of tens of thousands of years, even millions.

Re: Gaia spots stars flying between galaxies

#53

Post by pavel_lishin » Wed, Oct 03, 2018, 1:23 PM UTC

abecedarius wrote: post #46

pavel_lishin wrote: post #28

Earlier quoted context omitted.

There's at least two stories I've read with a similar premise; one was an interesting tale of a planet that stifles its scientific development, and is almost-unaware that they're about to approach another star. Damned if I remember what it's called, or who wrote it, though...

Perhaps https://en.wikipedia.org/wiki/The_Collected_Stories_of_Verno...

That's it!

Re: Gaia spots stars flying between galaxies

#54

Post by hyperpallium » Thu, Oct 04, 2018, 1:26 AM UTC

hyperpallium wrote: post #52

TeMPOraL wrote: post #51

Earlier quoted context omitted.

It would. I'd assume humanity knew about it for decades before it became "reachable" - preparing a colony ship (and creating a necessary infrastructure) would take many, many years. There's also a story to be found in the two planets being in radio range for a hundred years past leaving travel range.

I was thinking more of a scale of tens of thousands of years, even millions.

Let's say the rogue system is 4-40-400 light years away (nearest star is 4 ly).

What's a reasonable ∆v? We get some free ∆v from Earth's orbital velocity of 107,000 km/h, or 29.7 km/s. Our fastest spaceship (which is around sun, https://wikipedia.org/wiki/List_of_vehicle_speed_records#Spa...) is 252,792 km/h, or 70.22 km/s - which isn't including the ∆v to cancel that, ∆v to return to Earth, cancel again.

This 70.22 km/s is about 2 ten thousandths of the speed of light (70.22/299,792). It would take about 20,000 years for alpha centuri (4 ly) to arrive at that speed, and 200,000 years to travel 40 ly, 2,000,000 years for 400 ly.

Of course, maybe we can go faster in future. but propellant is a problem, you have to come back, and a manned mission is orders of magnitude heavier.

Space is big.

funexercise: propose a means of propulsion that could do this.

EDIT a new one is going 692,000 km/h, over twice as fast. At that rate of improvement, maybe we'll get closer to it sooner than I thought. https://www.space.com/41447-parker-solar-probe-fastest-space...

Re: Gaia spots stars flying between galaxies

#55

Post by leovuyk » Thu, Oct 04, 2018, 12:30 PM UTC

Surprise! Gaia satellite sees Stars flying between galaxies. Quantum-FFF Theory suggestion: Due to still undetected Galaxy Anchor Black Hole (GABH) gravity sources. at both sides of the spiral galaxy, in combination with Outer HI disc black hole "slingshots" for acceleration out of the galaxy.see: https://bigbang-entanglement.blogspot.com/2018/10/surprise-g... see: https://www.sciencedaily.com/releases/2018/10/181002103000.h... see also for "the origin of dead galaxies": http://vixra.org/pdf/1706.0490v2.pdf