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-   -   Why don't they crash? (http://www.trekbbs.com/showthread.php?t=238474)

QuarkforNagus February 20 2014 09:56 PM

Why don't they crash?
 
If these spaceships are going faster than the speed of light, then presumably they're moving faster than it would take them to see upcoming stars.

So how come they never run into one?

Warp speed is supposed to be like ftl right?

Lindley February 20 2014 10:05 PM

Re: Why don't they crash?
 
Technobabble explanation: Subspace sensors.
Real world aside: Paradoxes like this are basically the reason FTL is believed to be impossible.

Robert Maxwell February 20 2014 10:07 PM

Re: Why don't they crash?
 
Magic!

RoJoHen February 20 2014 10:39 PM

Re: Why don't they crash?
 
Why do the fictional ships never crash into the fictional stars?

Hmm...that's a tough one.

Metryq February 20 2014 10:40 PM

Re: Why don't they crash?
 
This reminds me of a story a police diver told the group one night. The police diver was the one who had arranged these "Tuesday night dives." The more people in the group, the less each had to pay the captain to take us out.

So on the way out of the harbor, the police diver told us about a recent incident where an intoxicated party-goer stepped off the fantail of the booze cruise ship and drowned. The police divers had to go down and look for the body before it bloated from decay and unceremoniously floated to the surface.

The water in the harbor is cloudy for various reasons. One could barely see the other divers just an arm length to the left and right. So the divers would swim along holding a knot in a rope, cutting wide swaths like a lawnmower. One of the group asked the police diver, "If the water was that cloudy, how did you find the body?"

The police diver smacked his forehead with a palm, "You run into it."

YellowSubmarine February 20 2014 11:20 PM

Re: Why don't they crash?
 
Why would they crash in stars? There are virtually no stars out there – space is void of stars, and the chance of ever encountering one is about zero. For example, our sun is huge and is moving unsteered. It's not that it can't see the coming stars, it can't ever change course to avoid them. Yet I don't fear it ever hitting one. Even when we go through Andromeda, we're safe from collisions. Not as safe from being ejected into intergalactic space – that's a cold ultimate demise, and might cost a fortune in delta-V budget to avoid.

Furthermore, star movement is fairly predictable. You know where a star will be, even if you can't see it. Q doesn't happen to move them at random. Remember that question someone asked in here – does gravity work at the speed of light, or instantaneously? Well, you can't ever directly measure the answer unless the sun disappeared by magic. However, it turns out its motion is so predictable that the planets that orbit it see it coming minutes or hours before the light comes to them (otherwise the orbits wouldn't be stable), regardless of the fact that evidence would suggest the effect is mediated at the speed of light. If there can be stable orbits, I'm willing to bet safe superluminal trajectories are also available. Just project the star position based on its known earlier position and velocity.




Now, to the really important question: Why don't they crash in lone hydrogen atoms that would possess like infinite kinetic energy or something?

Silvercrest February 20 2014 11:43 PM

Re: Why don't they crash?
 
Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star or ... oh, wait.

PhoenixClass February 21 2014 04:32 AM

Re: Why don't they crash?
 
Quote:

QuarkforNagus wrote: (Post 9271483)
If these spaceships are going faster than the speed of light, then presumably they're moving faster than it would take them to see upcoming stars.

So how come they never run into one?

Warp speed is supposed to be like ftl right?

They steer around them?

Quote:

YellowSubmarine wrote: (Post 9271918)
Now, to the really important question: Why don't they crash in lone hydrogen atoms that would possess like infinite kinetic energy or something?

That's what the deflector dish is for.

Mr. Laser Beam February 21 2014 05:42 AM

Re: Why don't they crash?
 
And besides, when a ship is at warp, it's not really "in" normal space, as such. It's in warp space, which is technically a different 'location'.

It's not until a ship drops OUT of warp that it becomes part of normal space again.

gturner February 21 2014 05:52 AM

Re: Why don't they crash?
 
Take the sun as an average star, with a diameter of 1.4e6 km. Assume the average star is the only significant object in a radius of 3 light years, then as you pass through them the cross sectional area (perpendicular to the ship's travel) has the empty circle being larger than the star in area by a factor of about 4.0e14. Given that ratio of empty area to stars (if plotted on a sheet), you'd have to travel across the entire diameter of the Milky Way about 250 million times to have a 1 percent chance of randomly hitting a star.

CorporalCaptain February 21 2014 07:34 AM

Re: Why don't they crash?
 
Quote:

Silvercrest wrote: (Post 9272008)
Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star or

This is one of the reasons why Star Wars is more realistic than Star Trek. :shifty:

Maurice February 21 2014 10:04 AM

Re: Why don't they crash?
 
Place a basketball in L.A. Place another basketball in NYC, then one in Berlin, Shanghai, and Capetown. Now, yank the Earth away and you have a nice scale model of a local cluster of stars (where the LA to NYC one is Earth to Alpha Centauri). Now, take a microscopic sand grain and shoot it in some random trajectory through that. The chances of it hitting one of the basketballs is about the same as the odds of ship hitting a star: effectively zero.

Metryq February 21 2014 11:52 AM

Re: Why don't they crash?
 
Quote:

YellowSubmarine wrote: (Post 9271918)
Remember that question someone asked in here – does gravity work at the speed of light, or instantaneously? Well, you can't ever directly measure the answer unless the sun disappeared by magic.

Actually, it has been measured. Astronomer Tom Van Flandern measured the "aberration" (angle) between the Sun's light and its gravity. I made a few animations for him to explain astronomical concepts, and one of the animations was aberration. Another was an animated version of "what if the Sun magically disappeared?"

I'll be dumped on by all the Professional Physicists™ for saying this (they can't abide dissent), but we don't know what gravity is. In fact, we're no further ahead than Newton who did not explain gravity, he merely quantified it. And that's all we can do today. (Yeah, yeah, I know. Einstein and warped space, but all that does is shift the question of gravity, it does not explain it.) The answer is that gravity—whatever it is—is faster than light.

Quote:

Maurice wrote: (Post 9274144)
The chances of it hitting one of the basketballs is about the same as the odds of ship hitting a star: effectively zero.

And if we look at the flip-side of that analogy, how do the starships so unerringly find the destination stars over such vast distances?

YellowSubmarine February 21 2014 12:59 PM

Re: Why don't they crash?
 
Quote:

Metryq wrote: (Post 9274306)
Actually, it has been measured. Astronomer Tom Van Flandern measured the "aberration" (angle) between the Sun's light and its gravity.

I wasn't talking about measuring the aberration, but the delay. The lack of aberration for gravity does not imply there wouldn't be a propagation delay if the sun vanished. If there was aberration, planets would not form stable orbits. On the other hand, if there was no propagation delay, that would allow for violations of causality, hence it's thought (but not directly measured) that there is a delay.

I was referring to a piece by Flandern (I think someone linked it here during the previous discussion?) where he explained how gravity is propagating at the speed of light while still being equivalent to Newton's view of infinite speed propagation, which is required to keep the orbits intact.

Hence my point: Stellar objects are moving without much acceleration, and pretty much predictably. Even if there's a humongous delay in the propagation of their image to you, the information reaching you is right about enough to plot your courses without aberration from their original position. Unless somebody pulls out a Picard Maneuver on you, you won't bump into anything.

Levi February 21 2014 05:30 PM

Re: Why don't they crash?
 
Is this question posed to the real world or the Trek world?


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