Discussion:
Inter-galactic civilizations
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a***@gmail.com
2020-01-31 10:49:57 UTC
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How far away is the nearest galaxy? Can we reach another galaxy using present technology?

Isolated star systems will possibly diverge in culture, technology, and biological evolution.

Has this been portrayed in recent SF?

Abhinav Lal

"Knowledge is virtue"
James Nicoll
2020-01-31 14:17:56 UTC
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How far away is the nearest galaxy? Can we reach another galaxy using present technology?
Much father than the nearest star, which we cannot currently reach. I will leave the
conclusion to you.
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a***@gmail.com
2020-01-31 14:52:21 UTC
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Post by James Nicoll
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
Much father than the nearest star, which we cannot currently reach. I will leave the
conclusion to you.
You are telling me what I already know. How many light years is the nearest galaxy?

Abhinav Lal

"The stars our destination"
Post by James Nicoll
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My tor pieces at https://www.tor.com/author/james-davis-nicoll/
My Dreamwidth at https://james-davis-nicoll.dreamwidth.org/
My patreon is at https://www.patreon.com/jamesdnicoll
-dsr-
2020-01-31 15:07:25 UTC
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How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.

We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".

-dsr-
a***@gmail.com
2020-01-31 15:30:19 UTC
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Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.

Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.

Abhinav Lal

"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
-dsr-
Peter Trei
2020-01-31 20:31:58 UTC
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Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel is The Breakthrough Starshot project, which proposes using huge lasers to accelerate small unmanned probes to 0.2c.

25 years to Alpha C., and 5 to hear back.

https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
J. Clarke
2020-01-31 23:30:54 UTC
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On Fri, 31 Jan 2020 12:31:58 -0800 (PST), Peter Trei
Post by Peter Trei
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel is The Breakthrough Starshot project, which proposes using huge lasers to accelerate small unmanned probes to 0.2c.
25 years to Alpha C., and 5 to hear back.
https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
Thanks to NASA using the name for some obsolete piece of shit, Orion
has been forgotten.
<https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)>.

It's the only kind of starship that we actually know how to build. It
was in the materials testing stage when various treaties rendered it
politically nonviable and the financial plug was pulled. Side
effect--a million tons to Mars in one shot--the thing you can't do
with an Orion is make it _small_.
Lynn McGuire
2020-02-01 00:58:00 UTC
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Post by J. Clarke
On Fri, 31 Jan 2020 12:31:58 -0800 (PST), Peter Trei
Post by Peter Trei
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel is The Breakthrough Starshot project, which proposes using huge lasers to accelerate small unmanned probes to 0.2c.
25 years to Alpha C., and 5 to hear back.
https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
Thanks to NASA using the name for some obsolete piece of shit, Orion
has been forgotten.
<https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)>.
It's the only kind of starship that we actually know how to build. It
was in the materials testing stage when various treaties rendered it
politically nonviable and the financial plug was pulled. Side
effect--a million tons to Mars in one shot--the thing you can't do
with an Orion is make it _small_.
For some reason, I am thinking that the Michael in _Footfall_ weighed
8,000,000 lbs. Am I wrong ?
http://www.up-ship.com/apr/michael.htm

Lynn
Dimensional Traveler
2020-02-01 01:37:45 UTC
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Post by Lynn McGuire
Post by J. Clarke
On Fri, 31 Jan 2020 12:31:58 -0800 (PST), Peter Trei
Post by Peter Trei
Post by a***@gmail.com
Post by -dsr-
How far away is the nearest galaxy?  Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years.  If we can reach the other edge of our galaxy, we can
possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space.  If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics.
If we could fund the development, technology of interstellar
unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Isolated star systems will possibly diverge in culture,
technology, and biological evolution.
It would be utterly miraculous if they did not.
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel
is The Breakthrough Starshot project, which proposes using huge
lasers to accelerate small unmanned  probes to 0.2c.
25 years to Alpha C., and 5 to hear back.
https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
Thanks to NASA using the name for some obsolete piece of shit, Orion
has been forgotten.
<https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)>.
It's the only kind of starship that we actually know how to build.  It
was in the materials testing stage when various treaties rendered it
politically nonviable and the financial plug was pulled.  Side
effect--a million tons to Mars in one shot--the thing you can't do
with an Orion is make it _small_.
For some reason, I am thinking that the Michael in _Footfall_ weighed
8,000,000 lbs.  Am I wrong ?
   http://www.up-ship.com/apr/michael.htm
Well, they did have to make it in a hurry so there wasn't time for all
the bells and whistles. :)
--
"You need to believe in things that aren't true. How else can they become?"
J. Clarke
2020-02-01 02:35:22 UTC
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On Fri, 31 Jan 2020 18:58:00 -0600, Lynn McGuire
Post by Lynn McGuire
Post by J. Clarke
On Fri, 31 Jan 2020 12:31:58 -0800 (PST), Peter Trei
Post by Peter Trei
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel is The Breakthrough Starshot project, which proposes using huge lasers to accelerate small unmanned probes to 0.2c.
25 years to Alpha C., and 5 to hear back.
https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
Thanks to NASA using the name for some obsolete piece of shit, Orion
has been forgotten.
<https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)>.
It's the only kind of starship that we actually know how to build. It
was in the materials testing stage when various treaties rendered it
politically nonviable and the financial plug was pulled. Side
effect--a million tons to Mars in one shot--the thing you can't do
with an Orion is make it _small_.
For some reason, I am thinking that the Michael in _Footfall_ weighed
8,000,000 lbs. Am I wrong ?
http://www.up-ship.com/apr/michael.htm
I don't recall the mass offhand and my copy of Footfall is paper,
making searching for such things more effort than I feel like
exerting. However that would be toward the small end of a viable
Orion.

What sets the lower bound of the mass of an Orion is maintaining a
reasonable level of acceleration. It basically has to be the smallest
thing that will accelerate at, say, 5G or less when you set of an
atomic bomb under it. And you don't want to use fizzle bombs to get
the mass down because that costs you efficiency. An ideal design uses
the most efficient bomb you can make, whatever size that turns out to
be, and is sized accordingly.

Of course if you have laser-induced fusion or some such the game
changes, but we don't know how to do that--we do know how to create
fission-bomb-induced-fusion though.
a***@gmail.com
2020-02-01 02:33:07 UTC
Reply
Permalink
Post by Peter Trei
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy using present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light years. If we can reach the other edge of our galaxy, we can possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If we find a way to accelerate close to the speed of light, less time will pass for the travellers, making the journey more manageable.
Post by -dsr-
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
There are two main constraining factors: technology and economics. If we could fund the development, technology of interstellar unmanned automated probes could be developed within a few decades.
Abhinav Lal
"Knowledge starts from ignorance"
Post by -dsr-
Post by a***@gmail.com
Isolated star systems will possibly diverge in culture, technology, and biological evolution.
It would be utterly miraculous if they did not.
Post by a***@gmail.com
Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
The only thing I'm aware of that's even close to interstellar travel is The Breakthrough Starshot project, which proposes using huge lasers to accelerate small unmanned probes to 0.2c.
25 years to Alpha C., and 5 to hear back.
One concern is how much money will be required to fund an interstellar probe. We may not get much of a return on investment, except for the knowledge we acquire.

Abhinav Lal

"Knowledge is virtue"
Post by Peter Trei
https://en.m.wikipedia.org/wiki/Breakthrough_Starshot
Joy Beeson
2020-02-01 05:34:13 UTC
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Post by a***@gmail.com
One concern is how much money will be required to fund an interstellar probe. We may not get much of a return on investment, except for the knowledge we acquire.
And we won't be around when the information comes back.
--
Joy Beeson
joy beeson at comcast dot net
http://wlweather.net/PAGEJOY/
Peter Trei
2020-02-01 06:35:05 UTC
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Post by Joy Beeson
Post by a***@gmail.com
One concern is how much money will be required to fund an interstellar probe. We may not get much of a return on investment, except for the knowledge we acquire.
And we won't be around when the information comes back.
Huh? 30 years from launch? I might not, you might not. But there are plenty of people
who would.

Voyagers 1&2 are still sending data, well over 40 years from their launches,
which I remember.

Pt
Joe Bernstein
2020-02-01 01:31:16 UTC
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Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're
150,000 and 200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years. If we can reach the other edge of our galaxy, we can possibly
reach another galaxy.
Though the journey will be very boring, traversing sparse space. If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
What's "we" in this scenario? You do realise that even at the speed
of light, distances like that essentially take long enough for
speciation to happen, right? I mean, 150,000 years is an
inconceivably long span for a generation ship. This isn't just a
"journey" for "travellers", this is the entire lives of many, many,
many generations of people.

Separate issue: how far is either Magellanic Cloud from *us* ? We
are, after all, not the same thing as "the Milky Way". English
Wikipedia sv "Magellanic Clouds" currently says they're 160,000 and
200,000 light-years away from *us*, but notes a study that "suggests
that the leading arm of the Magellanic Clouds is 90,000 away from the
Milky Way, closer than previously thought".

(And killer issue: When will we know enough about the relative
motions of the Clouds to us and to the Milky Way in general to be
able to *aim* this generation ship reliably? English Wikipedia very
strongly suggests one correct answer to that question is "Not yet".)

In a recent thread the question of the earliest generation ship story
came up, and I reported on reading a really weird story, mentioned as
a sort of precursor in the <Encyclopedia>, in which generation
*planets* were used to prosecute a war on a billion-year time scale.
There are reasons that's an idea weird beyond belief.

Joe Bernstein
--
Joe Bernstein <***@gmail.com
a***@gmail.com
2020-02-01 02:43:53 UTC
Reply
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Post by Joe Bernstein
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're
150,000 and 200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years. If we can reach the other edge of our galaxy, we can possibly
reach another galaxy.
Though the journey will be very boring, traversing sparse space. If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
What's "we" in this scenario? You do realise that even at the speed
of light, distances like that essentially take long enough for
speciation to happen, right?
IIRC, time slows down as you approach the speed light. Even though time outside will pass quickly. It has been over 25 years since I studied special relativity. Can anyone confirm this? What about the effects on mass?

If this is possible, then traveling to another galaxy can be done as quick as you want, if you can get arbitrarily close to the speed of light, in the travellers time.

Abhinav Lal

"What are the constraints?"

I mean, 150,000 years is an
Post by Joe Bernstein
inconceivably long span for a generation ship. This isn't just a
"journey" for "travellers", this is the entire lives of many, many,
many generations of people.
Separate issue: how far is either Magellanic Cloud from *us* ? We
are, after all, not the same thing as "the Milky Way". English
Wikipedia sv "Magellanic Clouds" currently says they're 160,000 and
200,000 light-years away from *us*, but notes a study that "suggests
that the leading arm of the Magellanic Clouds is 90,000 away from the
Milky Way, closer than previously thought".
(And killer issue: When will we know enough about the relative
motions of the Clouds to us and to the Milky Way in general to be
able to *aim* this generation ship reliably? English Wikipedia very
strongly suggests one correct answer to that question is "Not yet".)
In a recent thread the question of the earliest generation ship story
came up, and I reported on reading a really weird story, mentioned as
a sort of precursor in the <Encyclopedia>, in which generation
*planets* were used to prosecute a war on a billion-year time scale.
There are reasons that's an idea weird beyond belief.
Joe Bernstein
--
J. Clarke
2020-02-01 02:49:15 UTC
Reply
Permalink
On Sat, 1 Feb 2020 01:31:16 -0000 (UTC), Joe Bernstein
Post by Joe Bernstein
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're
150,000 and 200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years. If we can reach the other edge of our galaxy, we can possibly
reach another galaxy.
Though the journey will be very boring, traversing sparse space. If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
What's "we" in this scenario? You do realise that even at the speed
of light, distances like that essentially take long enough for
speciation to happen, right? I mean, 150,000 years is an
inconceivably long span for a generation ship. This isn't just a
"journey" for "travellers", this is the entire lives of many, many,
many generations of people.
If it's traveling close enough to the speed of light it's a few hours
for the crew. Google "time dilation". Read "Tau Zero" by Poul
Anderson. The big earth-shattering discovery in Relativity is that
time is not constant--motion messes with it.
Post by Joe Bernstein
Separate issue: how far is either Magellanic Cloud from *us* ? We
are, after all, not the same thing as "the Milky Way". English
Wikipedia sv "Magellanic Clouds" currently says they're 160,000 and
200,000 light-years away from *us*, but notes a study that "suggests
that the leading arm of the Magellanic Clouds is 90,000 away from the
Milky Way, closer than previously thought".
(And killer issue: When will we know enough about the relative
motions of the Clouds to us and to the Milky Way in general to be
able to *aim* this generation ship reliably? English Wikipedia very
strongly suggests one correct answer to that question is "Not yet".)
Their movement is of the order of 200 meters/sec. Over 150,000 years
that works out to about about 4E13 meters. A light year is about
9.5E15 meters, so Magellanic Clouds are going to move about .004 light
year in that time. The large one is about 14,000 light years in
extent and the small one about 7000. So their motion is going to be
pretty much a non-issue for a spacecraft moving at a large fraction of
the speed of light.
Post by Joe Bernstein
In a recent thread the question of the earliest generation ship story
came up, and I reported on reading a really weird story, mentioned as
a sort of precursor in the <Encyclopedia>, in which generation
*planets* were used to prosecute a war on a billion-year time scale.
There are reasons that's an idea weird beyond belief.
Joe Bernstein
Mike Dworetsky
2020-02-01 10:09:09 UTC
Reply
Permalink
Post by J. Clarke
On Sat, 1 Feb 2020 01:31:16 -0000 (UTC), Joe Bernstein
Post by Joe Bernstein
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're
150,000 and 200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years. If we can reach the other edge of our galaxy, we can
possibly reach another galaxy.
Though the journey will be very boring, traversing sparse space. If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
What's "we" in this scenario? You do realise that even at the speed
of light, distances like that essentially take long enough for
speciation to happen, right? I mean, 150,000 years is an
inconceivably long span for a generation ship. This isn't just a
"journey" for "travellers", this is the entire lives of many, many,
many generations of people.
If it's traveling close enough to the speed of light it's a few hours
for the crew. Google "time dilation". Read "Tau Zero" by Poul
Anderson. The big earth-shattering discovery in Relativity is that
time is not constant--motion messes with it.
Post by Joe Bernstein
Separate issue: how far is either Magellanic Cloud from *us* ? We
are, after all, not the same thing as "the Milky Way". English
Wikipedia sv "Magellanic Clouds" currently says they're 160,000 and
200,000 light-years away from *us*, but notes a study that "suggests
that the leading arm of the Magellanic Clouds is 90,000 away from the
Milky Way, closer than previously thought".
(And killer issue: When will we know enough about the relative
motions of the Clouds to us and to the Milky Way in general to be
able to *aim* this generation ship reliably? English Wikipedia very
strongly suggests one correct answer to that question is "Not yet".)
Their movement is of the order of 200 meters/sec. Over 150,000 years
that works out to about about 4E13 meters. A light year is about
I would want to double-check these figures, but I think that it's 200 km/s.
Post by J. Clarke
9.5E15 meters, so Magellanic Clouds are going to move about .004 light
year in that time. The large one is about 14,000 light years in
extent and the small one about 7000. So their motion is going to be
pretty much a non-issue for a spacecraft moving at a large fraction of
the speed of light.
Post by Joe Bernstein
In a recent thread the question of the earliest generation ship story
came up, and I reported on reading a really weird story, mentioned as
a sort of precursor in the <Encyclopedia>, in which generation
*planets* were used to prosecute a war on a billion-year time scale.
There are reasons that's an idea weird beyond belief.
Joe Bernstein
--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)
p***@hotmail.com
2020-02-01 03:55:48 UTC
Reply
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Post by Joe Bernstein
Post by a***@gmail.com
Post by -dsr-
Post by a***@gmail.com
How far away is the nearest galaxy? Can we reach another galaxy
using present technology?
If you count the Magellanic Clouds as different galaxies, they're
150,000 and 200,000 light years away from the Milky Way.
IIRC, the diameter of the milky way is a few hundred thousand light
years. If we can reach the other edge of our galaxy, we can possibly
reach another galaxy.
Though the journey will be very boring, traversing sparse space. If
we find a way to accelerate close to the speed of light, less time
will pass for the travellers, making the journey more manageable.
What's "we" in this scenario? You do realise that even at the speed
of light, distances like that essentially take long enough for
speciation to happen, right? I mean, 150,000 years is an
inconceivably long span for a generation ship. This isn't just a
"journey" for "travellers", this is the entire lives of many, many,
many generations of people.
Separate issue: how far is either Magellanic Cloud from *us* ? We
are, after all, not the same thing as "the Milky Way". English
Wikipedia sv "Magellanic Clouds" currently says they're 160,000 and
200,000 light-years away from *us*, but notes a study that "suggests
that the leading arm of the Magellanic Clouds is 90,000 away from the
Milky Way, closer than previously thought".
(And killer issue: When will we know enough about the relative
motions of the Clouds to us and to the Milky Way in general to be
able to *aim* this generation ship reliably? English Wikipedia very
strongly suggests one correct answer to that question is "Not yet".)
In a recent thread the question of the earliest generation ship story
came up, and I reported on reading a really weird story, mentioned as
a sort of precursor in the <Encyclopedia>, in which generation
*planets* were used to prosecute a war on a billion-year time scale.
There are reasons that's an idea weird beyond belief.
... Thus ended the second phase of the battle, the engagement of the two
Grand Fleets, with the few remaining thousands of Boskone's battleships taking
refuge upon or near the phalanx of planets which had made up their center.

Planets. Seven of them. Armed and powered as only a planet can be armed and
powered; with fixed-mount weapons impossible of mounting upon a lesser mobile
base, with fixed-mount intakes and generators which only planetary resources
could excite or feed.

Peter Wezeman
anti-social Darwinist
Dorothy J Heydt
2020-01-31 19:32:16 UTC
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How far away is the nearest galaxy? Can we reach another galaxy using
present technology?
If you count the Magellanic Clouds as different galaxies, they're 150,000 and
200,000 light years away from the Milky Way.
We can't presently send anything to our next closest neighbor star, which
is just 4 light years away. Except EM signals; we can do that.
....
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Has this been portrayed in recent SF?
Yes. The counter examples are basically "SF without a significant interstellar
component".
Recommended: James E. Gunn's _The Listeners._
--
Dorothy J. Heydt
Vallejo, California
djheydt at gmail dot com
www.kithrup.com/~djheydt/
Mike Dworetsky
2020-02-01 10:51:27 UTC
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How far away is the nearest galaxy? Can we reach another galaxy using present technology?
The two galaxies closest to our own are the Large Magellanic Cloud (163000
LY) and the Small Magellanic Cloud (200000 LY). They are dwarf galaxies
that are companions to the Milky Way Galaxy. Beyond that, the M31 galaxy
(Andromeda Galaxy) is about 2.5 million LY from ours.

Even with speculation about interstellar journeys involving known physics,
say at 20% of c, the journey times would be of order a million years or
more. So the only way a ship could get there would have to involve "warp
drive" or some such.
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Isolated star systems will possibly diverge in culture, technology,
and biological evolution.
Has this been portrayed in recent SF?
There are fictional portrayals of journeys or visits to one or the other of
these Clouds, ISTR. These all involve FTL travel. Even in the StarTrek
series, this is a big ask. For example, Voyager is trying to get home to
the Alpha Quadrant from the Delta Quadrant, both of which are in our galaxy
but on opposite sides, a journey of around 60 years or so, ship's time.

Can't cite any examples but ISTR such a trip to the vicinity of S Doradus
(LMC) in a Van Vogt(?) story, and a visit to some planet in one of Iain M
Bank's novels, possibly The Player of Games(?). Undoubtedly there are
others.
--
Mike Dworetsky

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