Maybe some examples? I’ve read a lot of his stuff, and can’t place this.
re “intercept,” one other possibility (I don’t remember the scene in the book) is that they want to get close to the same place as the other ship, so they can shoot the dickens out of it…even if they have to do that in a fraction of a second as the two pass by each other at very high speed.
This book quietly condenses conversations, eliminating, for dramatic sake, the very long pauses that would exist between sending a message and receiving a response. The sequel is worse, and the authorized second sequel, “Outies,” by Jennifer Pournelle, is even worse, as it portrays faster-than-light communication between different star systems, which absolutely violates the sf premise.
He completely misses the notion that if photons are entering your eye, then there must be something along that line of sight emitting the photons. Plenty of his works feature free-floating holograms which don’t have to be in line with their “projector”, and his Known Space books have the “blind spot” effect of hyperspace, which would actually just look black.
It’s not just his space faring universe. I’ve never heard deceleration being used anywhere in our universe outside of cars. Curious - Did your education at any point touch upon acceleration being a vector? I’m thinking in my school system it was covered at a point when everyone would have learnt it, but I may be wrong.
Regarding the not-in-line holograms; couldn’t they work by stimulating air to emit the right photons? That wouldn’t work in a vacuum I guess.
The blind spot would have to be a psionic effect, instead of a strictly optical one. I don’t have a problem with that, since he establishes that the mass detector is psionic, acting on the living mind directly.
Yeah, I think the blind spot is meant to be a bit spooky and unexplainable - you’re not seeing blackness or nothing, you’re seeing something that is even less than nothing. Sure, it doesn’t make sense, but neither does FTL.
On the subject of Niven’s grasp of optics, though, I think in one of the Ringworld books, a transparent GP hull becomes opaque in just one spot to protect the eyes of the crew from a distant bright source - except one spot would only protect the line of sight of one person.
Not really; it would be a simple (albeit somewhat expensive) matter of stationing ships at the Alderson points and having them pick up signals, carry them to the next system, and retransmit them.
Hmm… if GP hull can selectively polarize against a light source in a particular direction, would the crew perceive that as exactly the right spot becoming opaque to protect their eyes and the rest of the hull remaining transparent?
(Yes, I guess today is my day to fanwank Niven’s optics.)
Yes, absolutely. I know that magnitute and vector are part of the equation. But since I am not a physicist (or scientist at all) my only conversations since high school that relate to acceleration are about vehicles on earth. So, I naturally think of acceleration having a vector facing forward and deceleration as having a vector facing backward, even though “forward” and “backward” are totally relative terms and don’t describe what’s really going on at all in a scientific sense. In space, there is no forward or backward except into relation of other objects, and then it depends on whether you’re making that relation to the ship, the people inside, where it’s going, the nearest star, etc. I had forgotten to take that into account.
Mostly though it was just how deceleration was mentioned in the book once, but not mentioned again in other situations which I would have described deceleration to have taken place. Basically, the people in the book are talking correctly for the time period and lifestyle they’re in, but since I have never lived in space my brain took a bit to catch up.
Here’s what I understood from the explanation in the book. The alien ship was coming from interstellar space going straight towards the sun. So to match velocities, they had to first move the ship into the right vector, then accelerate to match speed. Because the alien ship is slowing down (it was using a light sail), you don’t have to be going as fast if you match velocities later as opposed to sooner. Here’s a plot of velocity vs time, with the alien in blue decelerating constantly, and two possible intercepts starting from a low relative velocity and accelerating constantly: http://i.imgur.com/qsud3sD.jpg. Where the lines meet is where they would have the same velocity vector, at which point if the human ship wants to stay with the alien they would have to turn around and start accelerating the other way. Of course orbital mechanics would also be playing a role, and I think a light say would also not produce a constant acceleration but I could be wrong, which may be why those two courses are specified.
Hell, all I need to care about from a story perspective is “they’re getting to the alien ship and they’re choosing the fast way”. They explained that well enough for me now that I’ve sorted out the whole acceleration thing so I’m not trying to pick apart every line that includes a reference to it.
It all started with the line, “Unlike merchant ships, which often coast long distances from inner planets to the Alderson Jump points, warships usually accelerate continuously.” and forgetting a bit of high school physics definitions.
The problem with your plots is that it shows where you match velocity with the other ship, but you may still be millions or billions of kilometers away from it. The tricky bit is to match both velocity and position simultaneously. That’s why Cziller said “I can use friends aboard my ship, but I’d sell them all for a competent sailing master.”
How about: the computer keeps real-time data on exactly where every crewmember is, including exactly where their eyes are, and selectively opaques the hull in spots directly between those eyes and a dangerously bright light source?
(We’re SF fans! We can fanwank anything!)
Except that (okay, I may be wrong here) signals can’t traverse Alderson points, only ships. And I don’t think the AI existed at a level necessary for drones or messenger torpedoes to pop in and out of Alderson points to send signals.
I don’t believe the books ever described an Alderson telegraph of this nature; the implication pretty much is that a ship has to go from place to place, carrying mail/signals.
in Moat and The Gripping Hand Niven and Pournelle get this right - there are lots of plot points that revolve around the impossibility of sending an interstellar message faster than a ship can travel. In fact just before the accelerate to intercept the Motie craft the MacArthur sends a message saying they’ve arrived in the New Caledonian system but Rod does not get a reply until hours later.
After the Lenin leaves the Mote the report has to travel by ship - not some sub-space radio! The navy has fast message sloops “manned by young crewman in perfect physical condition” that accelerate at 3G for long periods.
It’s Outies by Jennifer Pournelle that ignores this and makes no sense at all :smack:
Well, actually, to be fair, and leaving aside my gripe about communications, it’s actually a pretty darn good book and an honorable addition to the Motie universe. It’s easy to read, enjoyable, mostly makes sense. To be honest, I liked it better than “The Gripping Hand.”
So you send a message via laser in-system to the relay ship, the relay ship pops through the Alderson point to the next system, and then the relay ship sends a message via laser to your destination (or to another relay ship at another Alderson point in that system, etc.). There you go; FTL comms between systems, and you don’t need high accelerations at any point to do it.
You do waste time at each relay for the crew and the computers to recover from the Alderson jump, but yeah, it’ll be faster than having one ship take the message the whole way. The Pony Express of Pournelle’s empire.
True enough - it would cut down the time to get a message through from weeks to a day or so. I can’t think of any explanation of being given of why it wouldn’t work. In fact something like this is used in the Gripping Hand. The downside would be the need to station two ship permanently at each jump point. A big drain on resources but worth doing for key routes like Sparta to New Caledonia.
