Be Excellent To Each Other

Nicely written btw.

Bob is a Research and Development scientist at Ampex working on the development of Quadruplex video technology. His older self sends himself a quadtape.

The loop becomes stable when PastBob encounters a FutureBob that's healthy enough for them to collaborate and figure out a rule for what happens when an older PastBob is sent back to do the role of FutureBob. This is assuming that every loop expedites the development of the machine due to the increased availability of the information.

Until then there are variations. After then, old PastBob will follow the rules agreed by himself and his own FutureBob and ensure that the same rules are put in place on that next loop.

Bob is a Research and Development scientist at Ampex working on the development of Quadruplex video technology. His older self sends himself a quadtape.

How long before this loop becomes stable?

You see the VHS was the sticking point. If BobOne had survived the trip he could have explained in person. As it is, BobTwo can't watch the tape and has only the fevered notes of BobOne to go on.

Using the notes, BobTwo is able to speed up his development, but the scientific community still reject him. Come the mid 70s, BobTwo can watch the badly degraded tape

Nah, Bob is a scientist. He's got an artifact from the future!

Nah, Bob is a scientist. He's got an artifact from the future! The tape would surely contain proof, so he'd work on that first, which would at least convince a few of his colleagues. The cat is out of the bag then, and it's time-line disrupting stuff.

Turn it off and on again

Ian Smith was 22 years, 6 months and 1 second old. And he was pretty
dull. But he had decided to change that by inventing a time
machine (admittedly though it was one that could only head backwards through time,
but it's still better than anything you've managed). He realised he
had achieved this aim when he was sitting at his call centre desk
advising idiots to 'turn it off and on again' when the next
caller turned out to be himself. 'Hello Ian' Ian Smith, 23,
said. 'Er, Hi' Ian 22 1/2 replied, he was confused. The voice sounded
similar - but wrong - and out of breath. The other Ian was
also thinking this as well. For the second time today. He decided that the familiar
vibrations of his skull really added a husky deep quality to
his voice, and it upset him that the rest of the world didn't
get to hear it. He tried to explain this to the younger Ian
who response was to remain silent for so long that it caused
the line to switch off sending the hiss of white noise in
order to direct the bandwith towards the other billions
chattering on the network. This caused the older Ian to ask the
younger Ian if he was still there. To which he replied he
was.

It was a bad start, but at least broke the ice. Ian 23 went over the chinese whispers that explained what had happened. He had
got the 'explanation' off the Ian that told him about the
situation they had found themselves in. He himself had got it
off an older Ian and so on. This went back to the oldest Ian,
53, who discovered the time travel method after thirty years
hard work on his death bed. By which I mean he was in perfect
health until he jumped backed 10 years and embedded himself in
a swimming pool. Not the walls of the swimming pool, you
understand, the water. The molecules of water and his body
were intermixed quite thoroughly, and within minutes the water
had burst his cells, and thinned his blood. Ian, 43, who was
watching this was terrified. But watching the event, and
listening to the desperate hurried conversation of the dying
future him gave Ian the final break through on his time
machine he himself was currently working on. Ian, 43, after
wasting a week working out how to get rid of a future carcass
of himself (Solution: forget about it for now and send it back
a hundred thousand years with the time machine), finished
*his* time machine within the month and a decade ahead of the
last Ian. He went on to perfect the density detection circuits
to make sure he wouldn't end up in the middle of something and
jumped backed another ten years. Ian 33 watched Ian 43 spasm
and die on the floor as the air that was in the volume of
space his head now occupied fought to escape the nerve cells
and sinue that appeared there in a delicate poof. Ian 43
cursed himself for not realising this would happen but managed
to impart the lessons he had learned to the younger Ian before
he passed on. Ian 33's work on the time machine leaped ahead
with this knowledge and within the year he finished the
machine. Faced with the issue of time travel bends he was
afraid to use the machine - until he realised that
tele-porting a human sized vacuum the split second before he
transported himself would solve this problem by causing an
implosion/explosion that for a window of time a fraction of a
second wide should allow his safe passage. And so he went to
see Ian 23. (THIS DOESN'T WORK - they shouldn't have position
control - think of a different reason) Ian 23 however still
lived in London, where Ian 33 lived 5,000 ft higher up a
mountain in The USA. Of course the pressure difference had the
same bends effect and Ian 33 joined his dead future selves
within a few days. However he had long enough to tell Ian 23
exactly how to build the machine and what lottery numbers
would finance it's construction. Ian 23 , despite being
young, was still smart, and realised that he would need to
develop a suit to protect him from any pressure changes that
happened during a jump. This was a major breakthrough - as all
the later versions of the time machine couldn't transport
anything other than organic matter (or nothing itself of
course). Ian 23 had spent all his winnings in the production
of his machine and desiring more money filled his Personal A.I.
with lottery numbers, and stock details and decided to go back
and make some more money to finally have some fun with. Ian
realised, that maybe he had overlooked something, and had to
accept he might make a mistake. To avoid this he put a
detailed guide on the construction of the time machine on his
P.A.I. - but even this wasn't enough. He was quickly running out
of life to play with. His stupid future selves had wasted a
decade with each jump. Why?! Just to be consistent? Out of a
love of intergers?! The fools! Ian, 23, in a spiteful mood
towards his own idiocy set the machine to push him back 5
months 29 days, 23 hours and 59 seconds. As Ian, 23, slipped
into existence he realised his mistake in an instance. Of
course 5 months, 29 days, 23 hours and 59 seconds earlier the
Earth was 180 degrees behind in it's endless circling of the
Sun. He was 2 A.U. away from Ian 22 1/2. As his suit slowly
ran out out of it's supply of future air, Ian's PAI managed to
patch a call through to the electronics call centre he knew he
should be working in. (Hmmm how to end it? Turns him off the
idea, or he hangs up beliving it to be a crank call, but
inspires him to build a machine) Ian 23 had a few seconds left
till his air ran out. Finishing his story he prepared to
download the construction details (and lottery numbers) to his
younger self, but the download widget had crashed. 'Have you
tried turning it off and on again' Ian 22 1/2 helpfully
suggested.

If I were BobFive, I'd be wondering whether it's necessary for me to return to the past personally. I could just tie the notes to a brick and chuck it through. At the very least, I'd chuck through something unimportant to see if it made it, and then personally deliver the notes and the letter, which would include my hypothesis and expected results regarding the chucking.

"If you can see 80's TV guide I chucked through, then it won't be necessary for you to return personally. Just chuck the notes. Our invention kills you when you use it, and it really didn't look pleasant. I mean, when it happened to me I'd been woken up from a nightmare about a vortex, when I suddenly appear through a vortex gasping for breath and shouting about a vortex. Leave the vortex alone."

You'd have to be careful not to include anything from the package you received in the package you send. For example, Bob Senior's engraved pocketwatch to prove that it's really him.

Anything you both send and receive will age the intervening time with each loop.

Lave's is good, also. I love a good time travel story.

I wrote a crappy short story ages ago that was like this idea....

Why the hell not, here it is....

EDIT: Just had a quick glance at this again, I didn't even spell check it. It's very rough... I just wrote it when I couldn't sleep.

(damn Lave, stealing my damn thread)

Well, yeah. Assuming that the time travel widget locks you to one point in space, the only 'safe' place to make a trip would be in interstellar (or even intergalactic) space.