We have two distinct problems being discussed in this thread. One is whether a 15@ time machine will work in the word of the cave man, and the other is whether a cave man can learn to operate a 15@ time machine.
It is certainly possible to use a skill to travel from point A to point B that won't work to travel from point B to point A. The classic example is that it is really rather simple to open a gate from the border supernatural to any natural universe, but it might not be possible to open a gate from the universe to the border supernatural. It is interesting in this regard that the original Alexander Hartdeggen, time traveler in the H. G. Wells book, never attempted to travel to the past. In Wells' mind, the interesting thing to do with a time machine was always to go to the future. You might build a time machine that can take you to a point in the past in which the time machine would not work--or rather, in which you could not work it.
That is a key point. Many of our more sophisticated machines are built with @0 operation skills. The aircraft designer does not expect the pilot to understand how the airplane works, only how to work it. "Button pushing" skills which make it possible to operate a machine of which the user has little or no comprehension are @0 skills, and are never curved out. Thus assuming that our designer has created a machine that can be operated by a trained button-pusher, the machine will still work in any non-negative biased universe. You maybe can't build one, design one, fix one, sabotage one, or modify one, but you can make it work if it's designed that way.
Still, as John observes, it would require a 15@0 skill ability level to operate such a machine--maybe.
First, it is interesting to me that Bubba solves his problem by drawing a picture and showing it to the machine. This suggests to me the machine is not operated by use of a 15@0 operate time machine skill, but rather the machine is operated by an A.I. which is built into the control system, and the operator interacts with the A.I.--an artificial intelligence. The use of a user-friendly A.I. is only a 13@0 skill, so we've just saved ourselves 20 points.
Second, I don't know where you get the idea that Bubba the Cave Duck would have a 1@2 Intuition. Does he not live or die by his awareness of his surroundings, his ability to recognize danger and to spot advantage? I would be very surprised if he had less than a 1@10 intuition, particularly given that you've listed him as so unintelligent that he couldn't possibly think his way to anything. Bubba is a hunter. He needs the ability to avoid surprise. He could even be one of the outstanding cavemen, with a mid to high 2@ intuition. Let's suppose that he has a 2@5 intuition, +25 on his chance to learn.
We also have Launchpad. I don't know what it is about Launchpad, but he seems to have a 3@10 SAL at operating any transportation device. He probably has a 3@10 SAL at operating the A.I. that is the interface for operating this time machine. That's important, because Bubba learned how to do this by watching Launchpad--+40 on his chance to learn.
As mentioned, Bubba's bias is probably 3@. We know he can make and use clubs and spears--levers and wedges, all simple. That's 3@1, and it adds +31.
There is an uncertainty in all this which we actually can resolve. We have made the assumption that the bias reached 15@7 when someone invented this time traveling machine, the first device to be able to travel through time. Thus when we travel back to a point when the best humans could do was make clubs and spear points, we took the bias of the world back to 3@. But did we? People often ask me what the bias of our world is, and I always tell them that I can't answer that, because I don't have sufficient information. For example, I don't know for certain that there are not, right now, intelligent beings on another planet involved in time travel experiments. Indeed, there might be Galifreyans who have been jaunting about in their TARDISes since Earth was a cooling blob of magma. I don't have any evidence that such beings do exist, but I cannot rule them out. Thus it is possible that the ducks have moved to a point in the past where Earth's most advanced technologies are third level wedges and levers, but on planet Wolverine the evil wolves have been working with time travel for generations already.
Even without the supposition that there are technologically advanced intelligent aliens elsewhere in the universe, we do not need to assume that the area bias level of the universe is lower simply because no one has the skills within it. Remember, although bias reflects the skills of the indigs of a universe, it also reflects the intentions of the ruling deities. If when the Great Disney was creating the Duckverse, He determined that the tech bias in the Duckverse should be 15@10 so that Duckind would be drawn toward great achievement in all things technological, then that was the bias, even though no one knew it. The bias can't be lower than the highest skill in that universe, but it can always be higher. Yes, it often seems and often is so that what indigs learn raises the bias--it may also be that time travel skills will never be within the bias in any universe in which the bias must be raised to achieve them, or that however time travel is achieved it will not allow travel to a point in the past earlier than that achievement. (That is not so far fetched. The currently popular Wormhole Theory of time travel maintains that time travel is possible between the two ends of the wormhole, and thus between a time later than the creation of the wormhole and a time further in the future, but never earlier than the creation of the time machine itself.)
If the world area bias is 15@, that's +15 more.
Where are we now? We have 2@5 BRA+3@10 example+3@1 bias+15@world bias=111 against a 13@0 skill, putting us 19% shy of 0. So it would appear at first blush that Bubba cannot learn to operate the AI that operates the time machine.
On the other hand, we have another possibility.
If you look at the T1@2 Light Fire from Spark, it says that this skill:
includes (as separate skills under the same heading) the operation of a standard spark and fuel (butane,propane, et cetera) lighter, and a spark igniter for gas fires such as Bunsen burners and blowtorches (all positively sit-modded).
In other words, a cigarette lighter is the same concept as flint and steel, but has a +20 sit-mod because someone went out of his way to make the machine easy to use. In much the same way, you might have encountered touch screen computer interfaces at various commercial enterprises. The one that comes to my mind is that Sears catalog department once had such screens so that you could walk into that area of the store and instead of using their sales help get the information you needed by touching images on the monitor, which registered as information in the computer. You thus were learning a T11@0 Use Computer skill, and pretty certain to learn it, because the incredibly user-friendly user interface created a strong positive sit-mod. A.I. systems have a tendency to do that--they are made specifically to be user-friendly, in most cases. It may be that the A.I. on this machine was so intuitively simple to use that there was as much as a +40 sit-mod on it.
And that would make Bubba's chance of successfully learning to operate the A.I. that operates the time machine 20%, one chance in 5. That he got it on the fourth roll is not really that surprising.
--M. J. Young
