The difficulty with Hard Sci-fi

Don't these two quotes combine to make the whole thing impossible? Unless you decelerate to impulse speed every time you reach a lens, manoeuvre around, and then accelerate away again. Sort of slowing for a red light?

 

Back when I went to school, 12 months at 1014 antiprotons per month would have produced 12,168.

 

I think in the original text it was 10^14 and the "^" was lost in translation

The ship does not need to slow down to maneuver as it only needs to drift sideways a bit and than back. Whatever speed it is moving as seen by others, in it's own reference frame it's just a small movement there and back. The only problem is that when it moves out of the laser beam (and then in) for a moment it is only partially in it, and that causes a rotation that needs to be stopped.

 

1/ Going back to Chinspinner's original quote, it can't manoeuvre whilst in the beam, which is why my query about slowing down at the light.

2/ "it only needs to drift sideways..." it won't "drift" sideways, it will only travel sideways if a force is applied to it to make it do so.

3/ As a canoeist, I'm well aware of the sort of rotation that occurs when part of the vessel is in a moving current (the beam) and part in the eddy. Knowing the effect of the sort of shear forces that are applied when water is moving at maybe 25 mph, I can only imagine the problem when the current is flowing at light speed!

However, combining 2/ & 3/...as a canoeist, to travel across a fast-flowing body of water, I'd employ a "Ferry Glide"...turn the boat at a slight angle to the flow of water and paddle backwards. The slight angle acts like a rudder, and I balance my rearward paddling to the water's forward motion and the boat is squeezed like an orange pip towards one side or the other.

 

You would not need to slow down. If you wanted you could have the lenses move in and out of alignment to allow the ship to pass.

And yes the whole thing is impossible which is why no-one is doing it. It is minimal suspension of disbelief I am after, something that appears feasible.

 

The ship -in it's own reference frame- can do all kind of maneuver. I do not see anything that would prohibit this. The fact that it is accelerated by the beam means that this force should be taken into consideration but still it is not a prohibiting factor.

Eeeehhhhh... my bad, sorry. I wanted to express the kind of motion when the ship does not turn, just moves to the side. This can be done with normal rocket engines available and used today, so it's not rocket science.
Ooooops, it IS rocket science

The mentioned rotation is caused by two things : a) the thrust that is applied by the beam and accelerates the ship with 1 g when entirely in the beam and b) the friction caused by small particles that are most probably cleared from the ship's way by the beam but are there outside of the beam. My understanding is that the forces causing this rotation aren't small but they can be handled with maneuvering rockets.

 

To add to all the information in the original post, cost is the most important factor of all. Even if something like this were possible, there's a good chance it would never see the light of day because no one would pay for it. There's no profit to be made. Cost and funding are something most science fiction writers tend to ignore. Ironically, it's one of the easier things to explain.

 

Yeah, the costs would be astronomical and the benefits minimal.

 

I see what you did there.

 

Clearly to solve the fuel problem you just need an advanced yet adorable alien creature to poop dark matter into a litterbox. This provides two functions: readily available fuel and a precious traveling companion.

 

Its quite tempting. I could just solve mountains of tedious exposition with; "how does this thing work?"; "Rover here, he shits out dark matter."

 

As an aside, I just saw a scientific report that the speed of light in a vacuum isn't constant after all. Just something to keep in mind when it comes to the assurances we feel that what we think we know now is all accurate

http://www.newscientist.com/article/dn26837-shapely-photons-break-rules-to-fly-slower-than-light.html

 

Interesting. I used to subscribe to this as well, but can't find it anywhere in NZ.

 

Yeah, I thought it was cool. The differences are small, but one thing I try to keep in mind with respect to science fiction is that our understanding of the universe could change just as fundamentally in the next 100-200 years (or less) than it did over the time period from about the 1870s to the 1930s.

 

Yeah, I always wonder about this. Because I look back at the progress we made (and obviously my view is somewhat sharpened by hindsight), and none of it seems particularly outlandish to me. Phones, planes, computers... they were quite easily surmountable technological problems once we finally got pushed in the right direction (by the Industrial Revolution and subsequent wars).

But harnessing zero-point energy or anti-matter (dammit even nuclear fusion seems a century away), or manipulating space time whether through electro-magnetism or negative energy which might not even exist... they do seem insurmountable, at least within any reasonable time frame. Half of these technologies may not even be theoretically possible, let alone practically possible.

 

I was hoping people had seen Futurama and wouldn't be like, this girl is a moron

 

@Chinspinner

I do have those same views a lot of the time, but then I start thinking about how much of what we know now wouldn't have been considered theoretically possible in the 1800s, until new theories came along and turned everything on its head. Wasn't it in the 1800s that physicists were saying that all of the fundamental laws were discovered, and it was pretty much over except for the math?

What I wonder about in the future is whether there will be another theoretical upheaval of the kind we saw in the 1900s, and if there ever is how we can possible predict what it might be.

 

Whilst we stagnate with endless theoretical mathematics rather than practical experimentation I honestly doubt it. I suppose the theory of everything will be the next leap and perhaps it will tear apart either our understanding of classical physics or of quantum mechanics, or both. But after that I doubt I can even imagine it.

 

To actually contribute.

According to my husband, there is no way you would be able to slowly decelerate. The acceleration and deceleration would take a considerable amount of time so you would need a conventional thruster and fuel to achieve this.

Of course, he is also refusing to say anything more (even though he has a degree in aeronautical and astronautical engineering) and is wondering why you are spending so much time worrying about this instead of just giving a vague hand/\-waving and just telling the story, so take that with a grain of salt.

 

It is a beam craft. Effectively you have a space ship with a huge sail on it. A laser in orbit around our sun is fired at the sail and accelerates the craft (over about a year or so) via radiation pressure. There is a similar set up at the target star which fires a laser at the sail to decelerate the craft. That is the very short explanation.

A conventional thruster is impossible due to the fuel/mass escalation.

 

He said you're missing the point. If it's built in space, yes you are correct. But if you're taking off of Earth and landing on another planet that would be impossible. It's fine for long-distance traveling but when you get down to maneuver into orbits or other small-scale functions the laser wouldn't work for landings.

He said your answer is also your problem. If it takes a year to adjust to change course or slow down than it is also your problem. How are you going to do precise movements to the planet you are going to enter or leave without conventional thrusters. Are you going to wait a year to leave the planet again with lasers?

Edit: I told him it was a turn-on to listen to him talk all sciencey and he told me to stop.

 

“There will never be a bigger plane built.” - This was said by a boeing engineer about a plane that could hold ten people.

Got huge respect for the amount of research you've put into this, It already goes beyond what my thick skull can comprehend - just be careful when you start talking about what is and what isn't impossible; humans never fail to surprise and amaze.



Happy writing.

 

Your not is the simple answer. You are literally taking a straight line between two solar systems. You can get transported to and from the vehicle at either end (that would be the easy part).

 

He said that's fine then.

He hates forums so he won't say anymore. That ends my contribution because this stuff goes over my head.

 

I get his point though. Imagine there was a rogue planet about to hit you in the face at 5 light years from earth. You would have to send back a request for the laser to be adjusted to allow you to manoeuvre around it, which would take five years, then the laser would have to be altered which would take five years to take effect on the ship, meanwhile everyone is dead.

Of course this academic because the laser would probably no longer impart any thrust at five light years distant.