Does a Galactic Barrier Exist? Ask Here

[McHeathen]

Off course we should not take too seriously what we read in Sci Fi books. I've just been to lazy to do any research into the concept of a galactic barrier which was introduced to me in a trilogy of books called the 'Q Continium' by Greg Cox. So if anyone knows if such a barrier does exist then please let me know.

 

[Kt_Atis]

Probably not

 

[Parlyne]

As a rule, assume that Star Trek gets anything related to science wrong.

 

[DaveC426913]

They tried this in one of the movies and in the TV show. It was nonsense there too.

 

[yenchin]

Care to explain what this galactic barrier supposed to mean in science fiction?

 

[Kurdt]

Its a barrier of energy at the edge of the galaxy. There is also one around the centre of the galaxy. Its a fictional creation of Star Trek.

 

[B.E.M]

Yeah.. but if you are just looking for a wacky energy barrier justified by physics, you could google the "Domain wall"

http://en.wikipedia.org/wiki/Domain_wall"

http://www.damtp.cam.ac.uk/user/gr/public/cs_top.html#walls"

I think roughly it is when you have a phase transition such as water turning to ice, crystals that form adjacent to each other lock into a particular ordered structure, but crystals that form far apart cannot do this, so when the crystals grow to the point that they meet there is going to be a flaw in the crystal.

Apparently there is an analogy with the fundamental forces that separated out when the universe had cooled enough.. stuff nearby snapped into one configuration but stuff to far away to communicate might have snapped into another.

I don't really know what I am talking about but the upshot is there might be walls in space (but we haven't seen them) that separate one patch of physics from another with a huge gravitational force

 

[DaveC426913]

Care to explain what this galactic barrier supposed to mean in science fiction?

Well... in science fiction what it's supposed to mean is a plot vehicle to provide tension. In the real world, it is nonsense.

 

[DaveC426913]

I think roughly it is when you have a phase transition such as water turning to ice, crystals that form adjacent to each other lock into a particular ordered structure, but crystals that form far apart cannot do this, so when the crystals grow to the point that they meet there is going to be a flaw in the crystal.

Apparently there is an analogy with the fundamental forces that separated out when the universe had cooled enough.. stuff nearby snapped into one configuration but stuff to far away to communicate might have snapped into another.

Sounds a lot like a black hole to me.

I think if there were a barrier between parts of space that were fundamentally different, it wouldn't be a "wall" with a length and width (because that means the space on the other side has the same lengths and widths), I think the barrier would be much more elusive, for example it might be a barrier in apparent size. We might have to shrink ourselves down to smaller than the Planck length to gain access.

 

[Newbie says Hi]

Sounds a lot like a black hole to me.

Or even cosmological "domain walls" as postulated in some exotic theories. Well, anything that splits up the universe into cells would do I'd think. M-theory's "Horava-Witten domain walls" might fit the description too but I don't know ANYTHING about it :) But none of what I'm saying has been verified, and certainly none discovered that "surrounds" our galaxy... so it's pure fiction as far as we can tell so far.

 

[hellfire]

For a pedagogical introduction to topological defects (domain walls, cosmic strings, etc.) try this:

http://www.damtp.cam.ac.uk/user/gr/public/cs_top.html

 

[Newbie says Hi]

For a pedagogical introduction to topological defects (domain walls, cosmic strings, etc.) try this:

http://www.damtp.cam.ac.uk/user/gr/public/cs_top.html

Now if only there was a pedagogical introduction to "Horava-Witten domain walls" for non-string theorists :) They sound impressive enough. It would be really cool if we could get Witten himself to show up and explain it to us/me. Hmm, I wonder, does he know about the existence of PF?

 

[Kt_Atis]

If there were a galactic barriercould someone travel beyound this? What would one find and experience at the end of the galaxy IYO.

 

[Newbie says Hi]

If there were a galactic barriercould someone travel beyound this?

Ummm, I don't think anyone can really answer that.

What would one find and experience at the end of the galaxy IYO

The start of the rest of the universe, I'd presume.

 

[DaveC426913]

If there were a galactic barriercould someone travel beyound this?

Ghosts, faeries, Santa Claus.

When you apply 'what if's to what is a wild speculation in the first place, you fling the door wide to whatever fantasy you ... fancy.

 

[McHeathen]

Consider a hypothetical spaceship capable of warp drive going on an inter-galatic mission. Would this hypothetical spaceship have a problem with the graviational force of the entire Milky Way when leaving our galaxy?

 

[yenchin]

What do you mean by "warp drive", hypothetically?

 

[B.E.M]

Hey, don't tease, Yenchin!
McHeathen, that really is too hypothetical to answer. Speculations on warp drives usually already contain a series of practical impossibilities.

certainly the gravitational force of the galaxy is not that extreme from our point of view. The force of Earth is greater when standing on Earth (obviously) and normal matter certainly passes through galaxies without any problems, for example when galaxies collide.

here is an interesting link:
http://en.wikipedia.org/wiki/Alcubierre_drive"

 

[DaveC426913]

It's not hypothetical - the spacecraft 's motor is irrelevant. All that matters is the gravity well and the craft's velocity/acceleration.

Consider a hypothetical spaceship capable of warp drive going on an inter-galatic mission. Would this hypothetical spaceship have a problem with the graviational force of the entire Milky Way when leaving our galaxy?

It simply comes down to: what is the escape velocity of the galaxy? Apparently, according to Wiki, it is http://en.wikipedia.org/wiki/Escape_velocity" . So, if a craft wanted to coast out of the galaxy, it would need to gather an additional 780km/s before shutting off its engines.


Note: I talk about coasting because escape velocities are only meaningful if we have to worry about running out of fuel. If a spacecraft is able to run its engines continuously, then escape velocity is moot. (this is true whether escaping the galaxy - or Earth). Under constant thrust, a spacecraft will get away from a gravity well simply with persistence.

 

[B.E.M]

We are talking about a drive that circumvents one of the most fundamental laws of physics. You can probably fly out of a black hole or backwards in time with this thing. Who is to say the concept of escape velocity or even conservation of energy or momentum is still relevant?

 

[McHeathen]

It's not hypothetical - the spacecraft 's motor is irrelevant. All that matters is the gravity well and the craft's velocity/acceleration.



It simply comes down to: what is the escape velocity of the galaxy? Apparently, according to Wiki, it is http://en.wikipedia.org/wiki/Escape_velocity" . So, if a craft wanted to coast out of the galaxy, it would need to gather an additional 780km/s before shutting off its engines.


Note: I talk about coasting because escape velocities are only meaningful if we have to worry about running out of fuel. If a spacecraft is able to run its engines continuously, then escape velocity is moot. (this is true whether escaping the galaxy - or Earth). Under constant thrust, a spacecraft will get away from a gravity well simply with persistence.

Thanks Dave you have answered my question. As I suspected it is much larger than Earth's 11.186 km/s. BTW use of warp drive was only necessary to get to the edge of our galaxy.

So if it requires 220km/s to leave the solar system, then space probes sent to the outer planets, such as Voyager must remain in the (or maybe orbiting around it) solar system. Unless of course they have powerful thrusters.

 

[DaveC426913]

Thanks Dave you have answered my question. As I suspected it is much larger than Earth's 11.186 km/s. BTW use of warp drive was only necessary to get to the edge of our galaxy.

So if it requires 220km/s to leave the solar system, then space probes sent to the outer planets, such as Voyager must remain in the (or maybe orbiting around it) solar system. Unless of course they have powerful thrusters.

Whoa whoa. The escape v. of the SS is NOT 220km/s - that is NOT what I said.

What I said was the SS is orbiting the galaxy at 220km/s.

The spacecraft will escape the SS but will remain in orbit about the galaxy (or near the galaxy, perhaps on a long comet-like orbit) unless they can achieve 1000km/s. Only then could they coast to OTHER galaxies.

(BTW, again note that escape v. ONLY applies to coasting craft. You can escape a planet or a galaxy at 1km/h if you don't turn off your engines.)

 

[Astronuc]

Closer to home - in our solar system

Nearly eight billion miles away, the Voyager 2 spacecraft has passed through a sonic boom of solar wind particles in the outer part of the solar system, NASA scientists said. On Aug. 30, the craft detected the speed of charged particles from the Sun passing it abruptly slowing from 700,000 miles per hour to 350,000 miles per hour. Over the next two days, the spacecraft passed through the boundary four more times as the solar system’s “termination shock” bubble expanded and contracted. Voyager 2’s twin, Voyager 1, passed through the boundary three years ago, in the opposite hemisphere and about a billion miles farther from the Sun. The new data confirm a squashed shape for the magnetic bubble enveloping the solar system, which has been pushed inward in the southern hemisphere. Both spacecraft will eventually exit the solar system, perhaps as soon as 7 to 10 years from now.

http://voyager.jpl.nasa.gov/mission/interstellar.html

Also, NASA is planning to lauch the Interstellar Boundary Explorer (IBEX).
http://www.ibex.swri.edu/mission/index.shtml

The Voyager 1 (V1) satellite crossed the Termination Shock (TS) on December 16th, 2004 at a distance of 94 AU. . . .

However, Voyager 2 took a different path, entering this region, called the heliosheath, on August 30, 2007. Because Voyager 2 crossed the heliosheath boundary, called the solar wind termination shock, about 10 billion miles away from Voyager 1 and almost a billion miles closer to the sun, it confirmed that our solar system is “squashed” or “dented”– that the bubble carved into interstellar space by the solar wind is not perfectly round. Where Voyager 2 made its crossing, the bubble is pushed in closer to the sun by the local interstellar magnetic field.

http://www.sciencedaily.com/releases/2007/12/071210111958.htm

What is the implication for a 'galactic boundary' with respect to DM/DE? Is the boundary abrupt or a gradual transition - over what distance?