How do you define speed in space?

Palmpilot said:
In the aftermath of the experimental confirmations of the theory of relativity, I don't think anyone has come up with a definition of absolute speed that would make it observable or measurable.
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I supposed it would be akin to wondering if it was lunch or dinner that is blowing out your rectum.
 
Salty said:
I call bs.
Calculate 0x24 / 0x0C without a calculator and without converting to decimal first. I can easily do it in decimal.
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Sure but that's only because 0x0C (10) is a round decimal number. My point was that 10 itself is not otherwise a very naturally occurring number. We don't often buy or use 5 or 10 of anything, unless it's something artificially constrained to fit in with decimal or metric. Our world is full of rectangles, not pentagons.

Coming to math, calculating something like 0xFF00 / 0x10 or 0xFF00 / 0x100 is as trivial in hex as 9900 /10 or 9900 /100 is in decimal. However, that's where simplicity ends with decimal, but not with hex:

Observe these:
0xFF00 / 0x2 = 0x7F80
0xFF00 / 0x4 = 0x3FC0
0xFF00 / 0x8 = 0x1FE0

Now you may be confused - how is that easier that saying in decimal:
9900/2 = 4950
9900/4 = 2475
9900/8 = 1237

The reason is direct base conversion:

0xFF00 can also be expressed as: 0b1111 1111 0000 0000
/2 removes one digit at the end: 0b0111 1111 1000 0000
/4 removes two digits at the end: 0b0011 1111 1100 0000
/8 removes three digits at the end: 0b0001 1111 1110 0000

When you do this everyday, the conversion back and forth between 4-digit binary and 1-digit hex happen instinctive in your head - you can see the one number as the other. (I can anyway, but it took me a decade. A child can learn this in a month). So taking 0b1111 1111 0000 0000 and shifting it by 1, 2 or 3 digits become:
0b0111 1111 1000 0000 = 7 F 8 0
0b0011 1111 1100 0000 = 3 F C 0
0b0001 1111 1110 0000 = 1 F E 0

So now, not only can you trivially divide by 0x10, you can ALSO trivially divide and multiply by 2, 4, 8, 16, 32, 64, 128 (and 256 of course but that's just 16^2 (0x100) so equivalent to decimal 10^2 (100)).

Decimal has a similar trivial divide by 10 but doesn't have this easy back-and-forth base conversion. Well, it can of course convert to base 5 and get the same properties, but base 5 is not interesting enough in nature to make it worth our while. Rectangles, not pentagons.

Of course with hex you lose your ability to trivially divide by 10, but we only like dividing by 10 because we chose 10 as our base. If it wasn't chosen as the base, it would be about as common to divide by 10 as it would be to divide by 14.
 
Use binary, then you only ever need seven birthday candles.
 
There are 10 types of people in the world. Those that understand binary and those that do not.

The metric system was created for those who cannot count higher than 10(base10) without taking off their shoes.
 
Salty said:
I call bs.
Calculate 0x24 / 0x0C without a calculator and without converting to decimal first. I can easily do it in decimal. Even simple multiplication in hex is hard, only because we didn’t grow up memorizing the tables. 0x0A * 0x0C = ?, Childs play in decimal.

Ask someone to divide a pizza into 0x0A pieces and it’s the exact same difficulty as your example.
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DaleB said:
But that is my point. You can calculate 30/10 in your head instantly, simply because of the decimal notation. You can do the same thing in hex... 0x30/0x10 yields the same result and is just as easy to do. 12/5 in decimal is no easier than, say, 0x0c/0x05. Just as dividing a pizza into 10 slices requires the exact same amount of work whether you call it decimal 10 or hex 0x0A.
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deonb said:
Sure but that's only because 0x0C (10) is a round decimal number. My point was that 10 itself is not otherwise a very naturally occurring number.
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0x24 = 36 decimal
0x0C = 12 decimal
0x0A = 10 decimal
 
When writing your story you must remember there’s a much wider audience that does not understand or care about the mechanics of space travel. They’re only concerned about what happens when something goes wrong in space. The most popular series Startrek shows that you can accelerate from static to warp speed in about 1 second if you just “brace yourself” inside the ship, yet billions of dollars have been made showing incorrect theories that people (not nerds) CAN understand in their limited understanding of reality.
The creativity in writing space is more profitable (if that’s your goal) than being correct as 98% of your audience just wants to enjoy the read.
 
The one lady who knew just died a few days ago.
 
cowman said:
What would you make it relative to?
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In the Amazon show Expanse (cool show by the way) they often refer to speed not in the terms of an absolute figure like "55,000 kmh" but instead in rate of acceleration, IE, "accelerating at a 1G burn, we should arrive at X in Y days" .. half way through their trip the ships flip around and do another 1 G burn to decelerate by the time they arrive at their destination. Final velocity is the distance VS time covered

Honestly speed is kind of a made of thing, in its purely theoretical point it's just how much time it takes to get from two points

You could also make speed, if you're dying to have an actual "XX kmh" figure, you could make speed relative to the ship itself
 
Brad Smith said:
When writing your story you must remember there’s a much wider audience that does not understand or care about the mechanics of space travel. They’re only concerned about what happens when something goes wrong in space. The most popular series Startrek shows that you can accelerate from static to warp speed in about 1 second if you just “brace yourself” inside the ship, yet billions of dollars have been made showing incorrect theories that people (not nerds) CAN understand in their limited understanding of reality.
The creativity in writing space is more profitable (if that’s your goal) than being correct as 98% of your audience just wants to enjoy the read.
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True, but people who read scifi stuff also tend to be a little on the geekier side, so it's important that certain things are grounded in some "theoretically possible" reality. In Star Trek the reason you can jump to warp speed is because theoretically, when you create a warp field, the stuff inside the warp field doesn't actually accelerate, everything else accelerates around it.. there's some cool YouTubes out there around it, it's technically possible, just requires absurd amounts of energy. In Star Wars cannon (at least before Disney destroyed it) the ships gravity generators would be used to counteract the effects of acceleration, by basically pulling the occupants "forward" as the ship accelerated, so you wouldn't turn into meat pulp on the rear bulk head.. at least according to the old visual dictionaries. Star War's explanation now is probably going to be included in some dumb tweet and say it's because of "The Force" or some sh#t
 
Tantalum said:
In the Amazon show Expanse (cool show by the way)
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Would have been a lot better without the "proto molecule" stuff...

Brad Smith said:
When writing your story you must remember there’s a much wider audience that does not understand or care about the mechanics of space travel. They’re only concerned about what happens when something goes wrong in space. The most popular series Startrek shows that you can accelerate from static to warp speed in about 1 second if you just “brace yourself” inside the ship, yet billions of dollars have been made showing incorrect theories that people (not nerds) CAN understand in their limited understanding of reality.
The creativity in writing space is more profitable (if that’s your goal) than being correct as 98% of your audience just wants to enjoy the read.
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Just assume you are writing about aerodynamics for the FAA...
 
Capt. Geoffrey Thorpe said:
Would have been a lot better without the "proto molecule" stuff...
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Agree. Season 1 and 2 were a little hard to get through.. the latter two seasons though were better. I did appreciate the ship logic though.. none of what the ships did seemed that unplausible.. they couldn't jump to hyperspace or do anything of that sort. Jamie, the dude from Mythbusters, did some cool stuff with the Expanse guys

I also didn't really care for the lead guy, James Holder. I watched the show mainly for Amos, Naomi, and Cas Anvar, and the Martian girl (Draper?)
 
PS - why Space Odyssey was cool too.. non sounds in outer space.
 
Tantalum said:
You could also make speed, if you're dying to have an actual "XX kmh" figure, you could make speed relative to the ship itself
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The speed of the ship relative to itself is always zero.
 
Palmpilot said:
The speed of the ship relative to itself is always zero.
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Edit: I was thinking along the lines of how the INS works. The ship's starting point creates a static plane, the ship then, once moving, moves within that plane, where the plane is the reference point
 
Tantalum said:
True, but people who read scifi stuff also tend to be a little on the geekier side, so it's important that certain things are grounded in some "theoretically possible" reality. /
Right. That’s why I separated “nerds” from “normal” humans. It would be truer for a screen writer than a novelist to appeal to a wider audience that doesn’t have a clue about science. “Geeks” have a basic understanding of math and physics, something that most folks have no clue but are still able to enjoy sci-fi movies while remaining blissfully ignorant. The book market is indeed a different audience.
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Tantalum said:
Star War's explanation now is probably going to be included in some dumb tweet and say it's because of "The Force" or some sh#t
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Miticlorians. LOL.

They’ll zoom in on them happily pedaling on little hamster wheels, and have a plush toy from China available immediately. :)
 
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