# Time Travelling



## Dave (Jan 30, 2010)

We have many threads here at Chronicles about whether Time Travel is possible; what to take, who to see, where to go; or paradoxes that might occur. There is very little about the practicalities involved.

Obviously, you need some cash for spending money. No point in taking a circa 2010 £20 note back to 1950. Old coins are worth more than their face value. Gold and Silver are probably good, but where do you get hold of that?

You probably should take all your inoculations. If your ancestors survived the plague though, you probably share their immunity to it.

Then you need to look the part. You are going to stand out a little in trainers and a hoodie if you go back to 1840. So, you will need to have someone run up some costumes, or raid your local theatre wardrobe.

But I've just been watching the TV programme "QI" and I have discovered an even bigger problem I hadn't though about. The average height has been steadily increasing with time, so that oft quoted fact that Napoleon was short is not actually true. At 5ft 7 he was average height for that time period. As you go back further, the heights grow shorter. If you look at old armour or coffins they always look like they were made for children, and door frames in old houses are always very low so I have to stoop down. So, any Time Traveller back in Time is going to stand out like Goliath to David, and anyone going into the future will be a dwarf. Not much one can do about that problem.


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## drush9999 (Jan 30, 2010)

Other problems are language, the way Latin was spoken when Julius Caesar was around, or Old English a 1000 years ago.
You'd more likely stand out because you didn't bow to a passing nobleman, or simply walked in a different way.
Let alone bringing back diseases that hadn't evolved yet...

For some reason I think about this all the time, would love to check out famous events and people before photos and film/video were available.


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## Pyan (Jan 30, 2010)

Dave said:
			
		

> The average height has been steadily increasing with time



Surely the key word there is "average",Dave - there will always have been people that were taller or shorter than the average height for the era. How far would a persop have to go back before a height of, say, 5' 11" really stand out enough to arouse suspicion that he might not be "normal"?



			
				drush said:
			
		

> Let alone bringing back diseases that hadn't evolved yet...



Or indeed, be immune to ones that everyone caught as a matter of course? A vaccination mark in itself would be difficult to explain - remember Brad Pitt as Achilles in _Troy_...


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## The Judge (Jan 30, 2010)

Well, Charles II was 6ft tall ('two yards high' I think the description was), which was unusual in the 1650s, but no one appears to have demonised him on that account.

As for costumes, I don't think the local am-dram wardrobe will cut it, somehow.  But I don't recommend hoping to find some spare clothes lying about either - that's when the average height issue (and bust and waist size for ladies) will create problems.


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## Ursa major (Jan 30, 2010)

The Judge said:


> Well, Charles II was 6ft tall ('two yards high' I think the description was), which was unusual in the 1650s, but no one appears to have demonised him on that account.


To be fair, it was thought bad manners to even broach the subject of reducing his height after the less-than-successful operation on his father. 



The Judge said:


> As for costumes, I don't think the local am-dram wardrobe will cut it, somehow. But I don't recommend hoping to find some spare clothes lying about either - that's when the average height issue (and bust and waist size for ladies) will create problems.


True. Decades ago, I read a novel about the "witches" of Pendle. As part of the info-dumping there was a description of the inordinantly complicated dress of that time. (The POV character, a (gentle?)woman, had all sorts of under-petticoats to deal with. One could travel as a destitute peasant, I suppose, but I doubt it would give one much freedom of travel in some societies.


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## The Judge (Jan 31, 2010)

Ursa major said:


> To be fair, it was thought bad manners to even broach the subject of reducing his height after the less-than-successful operation on his father.


Since the description was part of a Wanted poster issued by the Roundheads, I don't think bad manners would have deterred them - and I imagine they thought the operation a complete success in making Charles I 'shorter by the head'! (The quote is from Elizabeth I, who also had such body- and life-shortening operations carried out).


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## TheEndIsNigh (Jan 31, 2010)

The Judge said:


> Well, Charles II was 6ft tall ('two yards high' I think the description was), which was unusual in the 1650s, but no one appears to have demonised him on that account.
> 
> As for costumes, I don't think the local am-dram wardrobe will cut it, somehow. But I don't recommend hoping to find some spare clothes lying about either - that's when the average height issue (and bust and waist size for ladies) will create problems.


 
Well I'm not so sure J. 

It might have been the real reason no one liked his dad and look what happened there.

EDIT:

Look we're going to have some kind of posting syncronisation system. Ursa beat me to it. 

Even worse you replied before I could get in. 

Rats


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## mosaix (Jan 31, 2010)

TheEndIsNigh said:


> Look we're going to have some kind of posting syncronisation system. Ursa beat me to it.
> 
> Even worse you replied before I could get in.
> 
> Rats



You need a time machine.


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## Montero (Jan 31, 2010)

In terms of costumes am-dram wouldn't cut it - re-enactors would though.   You'd need to be super-careful and use hand loom woollen cloth not machine woven - some weave patterns today were unknown then and any weaver or clothier you passed in the street would be caught by it.

Check out Kentwell Hall for example of re-enactors.

Here Award Winning Re-Creations at Kentwell | Kentwell, Suffolk, UK
and
Here The Tudor Costume Page

Height is not necessarily a problem - there were some tall people - Henry 8th, Rupert of the Rhine as well as Charles II.  The Scots were generally taller than the English apparently, due to a more nutritious diet based on porridge and fish.  Good skin and good teeth would make you a bit special in some circles. 
Language would be a problem as would suspicion of strangers.  Being a rich foreign merchant and hiring local servants would be a good start.
Bear in mind that even today we can't always understand local accents from the other end of the country, but we are at least open to the idea that they exist.  There were certainly occasions when an Englishman travelling well away from home inside England came under suspicion of being a foreign spy as he spoke foreign.
Need to perhaps be careful of when you chose to travel - there was a lot of fear of Spanish spies in the Elizabethan period and of the wild Irish during the civil war.  The English Civil war followed a period of English colonisation of Ireland, uprisings, and refugees.  There were many stories of atrocities, most not true.  One of the scare stories of the English Civil War was that Charles I was going to bring in Irish troops to fight in England.  After the Battle of Marston Moor, the Welsh women in the Royalist bagage trayne were taken to be Irish - they didn't cover their hair, had long knives and spoke a wild foreign language - and they were mutilated and slaughtered.


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## Montero (Jan 31, 2010)

TheEndIsNigh said:


> Well I'm not so sure J.
> 
> It might have been the real reason no one liked his dad and look what happened there.



Charles I was short as was his Queen - even for the period.  Charles was very dignified and elegant, his Queen tended to patter around excitably from what little I've heard.


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## Montero (Feb 2, 2010)

Body language is probably another give-away - not necessarily consciously, but in a way that would make people uneasy. 

Mind you, wearing clothes to exact period specification does alter the way you move.  The only way to walk in bucket top boots is to swagger.

Nothing to do with time travel, but Janet Kagan deals with body language rather interestingly in Hellspark.


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## Dave (Feb 11, 2010)

Don't you hate it when you think you have an original idea, only to find someone else has already had it before? 

The many authors here must frequently find that someone has already also published the book too. 

That's what I found today. I have just bought a book called *The Time Traveller's Guide to Medieval England* by Ian Mortimer ISBN 9781845950996.



> Imagine you could travel back to the fourteenth century. What would you see, and hear, and smell? Where would you stay? What are you going to eat? And how are you going to test to see if you are going down with the plague?



It is a bit like _The Hitchhikers Guide..._ for Time Travellers. An essential book if you are going to travel to world in which sheep are the size of dogs, 30-year-old women are regarded as so much "winter forage", and green vegetables widely held to be poisonous.



> The past is a foreign country - they do things differently there.
> 
> L.P. Hartley, _The Go-between_



The Bookseller said he had just read it and recommended it.


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## The Judge (Feb 11, 2010)

Dave said:


> It is a bit like _The Hitchhikers Guide..._ for Time Travellers. An essential book if you are going to travel to world in which sheep are the size of dogs, *30-year-old women are regarded as so much "winter forage"*, and green vegetables widely held to be poisonous.


They fed the pigs with them??  One way of getting rid of the surplus population, I suppose.


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## Dave (Feb 11, 2010)

No, that is a line from Chaucer, he is inferring something else - when fresh produce is not available.


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## The Judge (Feb 11, 2010)

Oh dear.  Showing my literary ignorance here!  I would have got 'The Go-Between' quote, so I suppose one out of two isn't bad.


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## michaelhall2007 (Mar 25, 2016)

Dave said:


> We have many threads here at Chronicles about whether Time Travel is possible; what to take, who to see, where to go; or paradoxes that might occur. There is very little about the practicalities involved.
> 
> Obviously, you need some cash for spending money. No point in taking a circa 2010 £20 note back to 1950. Old coins are worth more than their face value. Gold and Silver are probably good, but where do you get hold of that?
> 
> ...


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## michaelhall2007 (Mar 25, 2016)

What do you think they'd actally do if your were dumb enough to get caught?
Lets say they figure it out in the next 10 years and you went back to 1985 to see if Michael Jackson realy was black. 
Would the scientist and government really be all white coats and guns like in ET & Flight of the navagator?
Additional: You managed to hide the Delorion.
Also this question is research for a book idea Ive started.


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## Dave (Mar 25, 2016)

Unless it was a hushed-up, government-white-coats, Roswell-style conspiracy, then for a start, it would fundamentally change our way of thinking about our world. You wouldn't be the last, but only the beginning of time tourism. You would be lauded as an international celebrity, and appear on every reality TV show. It would be impossible to prevent pollution of technology and ideas from the future to the past, or of stealling rare items of value to take to the future. This would be year zero and we would begin counting the years TT - post time travel. I don't think it would be great for our society. It would like a seven year old getting the key to the sweet shop. So, for your story you need to employ that old standard of tiime travel stories and hobble your machine in some way - it is damaged and only works one way before blowing a flux capacitor, running out of power or frying it's circuits.


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## WaylanderToo (Mar 25, 2016)

could you imagine taking an Abrahms or Leopard II tank back to WWII or WWI... or even earlier, English Civil War... Thermopolae...


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## galanx (Mar 26, 2016)

The topic is dealt with in Alfred Bester's "Hobson's Choice".


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## galanx (Mar 26, 2016)

WaylanderToo said:


> could you imagine taking an Abrahms or Leopard II tank back to WWII or WWI... or even earlier, English Civil War... Thermopolae...



Absolutely deadly- until it ran out of fuel. And ammo. and the guidance/engine /electronics broke down.


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## Dave (Mar 26, 2016)

The first Sontaran Doctor Who story _The Time Warrior _also deals with modern technology taken to the past. (Also notable for the first appearance of Sarah Jane Smith, first mention of Galifrey and a young June Brown.)

I agree with galanx, I think fuel/power and ammunition are the biggest problems a would-be time traveller would encounter in using his gadgets and weapons. You could make low voltage batteries for light and motors (a potato can power enough LED lamps to light a room for a month but other vegetables would work) but the kind of electricity required by modern machines would be nigh impossible. (_Back to the Future _had the Plutonium powered car stuck in the 1950's.) Simple wear and tear of parts would be another problem, unless he has a 3D printer from the late 21st Century.


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## michaelhall2007 (Mar 26, 2016)

Dave said:


> Unless it was a hushed-up, government-white-coats, Roswell-style conspiracy, then for a start, it would fundamentally change our way of thinking about our world. You wouldn't be the last, but only the beginning of time tourism. You would be lauded as an international celebrity, and appear on every reality TV show. It would be impossible to prevent pollution of technology and ideas from the future to the past, or of stealling rare items of value to take to the future. This would be year zero and we would begin counting the years TT - post time travel. I don't think it would be great for our society. It would like a seven year old getting the key to the sweet shop. So, for your story you need to employ that old standard of tiime travel stories and hobble your machine in some way - it is damaged and only works one way before blowing a flux capacitor, running out of power or frying it's circuits.


Thanks for your  input. I've got to start thinking outside of the box. The trick would be,  to go public before the men in white coats get you first.


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## Mirannan (Mar 26, 2016)

Going back maybe 40 years, with the gadgetry most of us carry around these days (and even supposing you happen to have the charger on you) saying anything about the stuff would get you locked up in a mental institution. Take my smartphone (low-end):

"You say that tiny thing has a gigabyte of memory and 8 gigabytes of storage? Ridiculous!" (A high-end mainframe of the late 1970s, the IBM 370/165, had 120MB of disk storage and 128K of RAM.)


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## michaelhall2007 (Mar 26, 2016)

Mirannan said:


> Going back maybe 40 years, with the gadgetry most of us carry around these days (and even supposing you happen to have the charger on you) saying anything about the stuff would get you locked up in a mental institution. Take my smartphone (low-end):
> 
> "You say that tiny thing has a gigabyte of memory and 8 gigabytes of storage? Ridiculous!" (A high-end mainframe of the late 1970s, the IBM 370/165, had 120MB of disk storage and 128K of RAM.)


You've given me a few things to think about.  Thankfully,  before I will ever put pen to paper,  I'm researching and researching, to which I have a degree in


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## michaelhall2007 (Mar 26, 2016)

I've even sent a communication to Oxford  Uni's Theoretical Physics dept asking questions because I think that's where they'd send me. Not Hawkings but some one far enough down the food chain to ask around.


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## Ray McCarthy (Mar 26, 2016)

Mirannan said:


> and even supposing you happen to have the charger on you


Oh I could have knocked up a replacement charger 40 years ago. (I think maybe at earliest 1967, I was pretty inept and clueless in 1965 when I started learning Electronics.)
Not the Phone base station. But my phone has also a built in FM Radio that would have worked in 1945 in USA or 1949 Germany or 1955 Uk (1962 in Ireland!). The USA 1930s to 1945 FM Radio used a lower VHF band, not on ordinary FM sets, though some 1960s to 1990s models with TV sound reception can do the old USA FM Radio band (Later Band I TV, 405 in UK, 525 in USA, 819 France / Belgium and 625 rest of Europe, the UK and France used AM though for TV sound)

The earliest that someone EXPERT could make a time travelling visitor a charger, would maybe 1801, Volta demonstrated batteries in late 1799. By 1801 or maybe 1803 Electropotentials of various metals known, I think, so a close enough supply to 5V could be made without test gear, just by first principles. The Maths for FM Radio in late 1920s I think. Armstrong demonstrated FM Radio in 1930s , but contrary to US patents, he never invented it. AM radio was known nearly 20 years before public broadcasts started in 1921.

Entropy suggests only forward time travel is possible. I take a jump forward once a day ...


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## michaelhall2007 (Mar 26, 2016)

Ray McCarthy said:


> Oh I could have knocked up a replacement charger 40 years ago. (I think maybe at earliest 1967, I was pretty inept and clueless in 1965 when I started learning Electronics.)
> Not the Phone base station. But my phone has also a built in FM Radio that would have worked in 1945 in USA or 1949 Germany or 1955 Uk (1962 in Ireland!). The USA 1930s to 1945 FM Radio used a lower VHF band, not on ordinary FM sets, though some 1960s to 1990s models with TV sound reception can do the old USA FM Radio band (Later Band I TV, 405 in UK, 525 in USA, 819 France / Belgium and 625 rest of Europe, the UK and France used AM though for TV sound)
> 
> The earliest that someone EXPERT could make a time travelling visitor a charger, would maybe 1801, Volta demonstrated batteries in late 1799. By 1801 or maybe 1803 Electropotentials of various metals known, I think, so a close enough supply to 5V could be made without test gear, just by first principles. The Maths for FM Radio in late 1920s I think. Armstrong demonstrated FM Radio in 1930s , but contrary to US patents, he never invented it. AM radio was known nearly 20 years before public broadcasts started in 1921.
> ...


Good to know. Thanks


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## Dave (Mar 26, 2016)

Yes, the time traveller not being believed and trying to contact scientists (_Galactica 1980_) and being locked up in the insane asylum (_Twelve Monkeys_) are other recurring themes in time travel stories.


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## michaelhall2007 (Mar 26, 2016)

Instead,  indeed. But I shouldn't really be researching my book on this forum so I've opened one in the writers discussion forum called TIME TRAVEL (THE PITFALLS)


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## Old_Man_Steve2016 (Mar 31, 2016)

One pitfall people forget about (except maybe on New Doctor Who) is _skin color_. If I'm not fulfilling some sort of temporal prophecy, then practically anywhere I go before 1492, with specific exceptions, is bound to wreck the timeline. Similarly, a white guy tooting around pre-Columbus Americas is going to raise a stir, if not a plain ole' ruckus. Something to keep in mind when deciding when to go, how to operate when there (stealth or 'go loud'), and how to expect dealings with the locals to go down.


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## Mirannan (Mar 31, 2016)

Old_Man_Steve2016 said:


> One pitfall people forget about (except maybe on New Doctor Who) is _skin color_. If I'm not fulfilling some sort of temporal prophecy, then practically anywhere I go before 1492, with specific exceptions, is bound to wreck the timeline. Similarly, a white guy tooting around pre-Columbus Americas is going to raise a stir, if not a plain ole' ruckus. Something to keep in mind when deciding when to go, how to operate when there (stealth or 'go loud'), and how to expect dealings with the locals to go down.



Wrong on both counts, I think. (From the way you put this, I assume you're black; it doesn't matter to me one way or the other.)

Although fairly rare, people with very dark skin (from present day Somalia and Ethiopia, at the very least, and southern India) were known even in Roman times or before. And white Caucasians - in fact Nordic people - visited at least some parts of North America hundreds of years before Columbus.


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## Ray McCarthy (Mar 31, 2016)

Mirannan said:


> were known even in Roman times or before


In Old Testament, really old Welsh Legend and really old Irish Legend. Queen Of Sheba from Somalia/Ethiopia region on coast and Kingdom of Kush may have partly encompassed Yemen.

I think actually darker skinned people were well known in Roman times, in Rome anyway. Cleopatra was really more Greek than Egyptian, but for political reasons "at home" played up the African stuff. Alexander the Great conquered North Africa, on his death one of the four Generals ruled it. Cleopatra was a descendant.

Vikings in Greenland 100% visited Canada. It's not so sure if Welsh and Irish really did, but certainly some stories suggest it.* Note that Donegal or Scottish Western Isles are closer to Canada than Greece.* The Phoenicians before 300 BC (roughly present day Lebanon), Greeks and Romans all traded with Western Atlantic Bronze Age Celts (Tin from Cornwall and Copper from Cork, Ireland) to make Bronze and Brass.
Phoenician items in Bronze age graves in Ireland.
Flat maps are deceptive. Check out "great circle routes".

Going via Scotland/N.I., Iceland, Greenland and to Newfoundland is pretty easy compared to Spain to Caribbean or Egypt to Ireland.  Ancient Arabs sailed as far as India and may have visited China and even New Zealand.



Old_Man_Steve2016 said:


> Similarly, a white guy tooting around pre-Columbus Americas is going to raise a stir, if not a plain ole' ruckus.


No. It wouldn't. Also Indigenous North Americans are not hugely different to some Asians north of China. 

Outdoor "white" people can be as "dark" as many Asians and Indigenous Americans.

Even Africa historically 2000 years ago had near white blue eyed (Berbers) to what in Irish is literally "The Blue Men" (Very dark Ethiopians). Even today, there is MORE genetic variation in Indigenous Africa than rest of world, variation from short to tall, skin tone, hair types and more. Even non-genetic stuff such as languages and culture.

Africa not only had amazing Civilisations in the North (not just Egypt) but Zimbabwe and Benin


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## Dave (Apr 1, 2016)

Ray McCarthy said:


> Africa not only had amazing Civilisations in the North (not just Egypt) but Zimbabwe and Benin


Excised from "western" history books because there was no "paper" record of them existing and because it was convenient during the European struggle to colonise Africa to believe that Africa had no history until it was civilised by Europeans. There is plenty of archeological evidence available, and probably a great deal more yet to find. There is much written in modern historiography about this subject since even after African states gained independence, their own native historians tended to be Western educated men, who were taught the same views that had been propagated by the colonial powers fifty years earlier. So, it is only now that anyone is peeling that away to look further back.


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## Ray McCarthy (Apr 1, 2016)

Dave said:


> Excised from "western" history books


Can they be "excised" when no-one bothered adding them in the first place?


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## Ray McCarthy (Apr 1, 2016)

Vikings further into Canada than thought ...

New evidence of Viking life in America? - BBC News


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## J Riff (Apr 1, 2016)

I still ike the idea of time-dilating off and away at light speed, then returning. Just keep doing it and pretty soon it's the yeAR 4000 and you are still young, and can finally get an affordable flying car.


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## galanx (Apr 2, 2016)

I remember a short story set along those lines, where the spacers had become almost a separate ethnic group; because while no time had passed for them whole civilisations had risen and collapsed on Earth, so they were the only people that shared common memories and cultural habits.


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## Old_Man_Steve2016 (Apr 2, 2016)

Ray McCarthy said:


> No. It wouldn't.


Yes it would because there are times when it clearly DID (cause a stir, not wreck the timeline). 
1) The Spanish Conquest of the Aztecs. Now there is a 'caveat' with this theory in that the Aztec are said to have received 'omens' of a people, "fighting men riding "on the backs of animals resembling deer", in a mirror on the crown of a bird caught by fishermen." nine years prior to the arrival of Cortes. 
_Wait a minute...fighting men on the backs of animals....strange crowns..._





John Wayne was a time traveler????? Someone dig up his grave and make sure his body is still in it!!!
2) There were African mercenaries operating in Korea during the Imjin war. While China had trade deals with African kingdoms, there was not a lot of cross population between them (The Canton region had African slaves called kunlun but the source I read said they were not found outside of Canton). So, the presence of the African slaves and mercenaries caused a big stir in 16th century China and Korea, even enough for their presence to be noted in historical texts (and artwork). 





3) The story of Hamel the Dutch sailor marooned in Joseon-era Korea should be a cautionary tale to any time-traveler.  His (and his crew's) presence caused a big stir, and attempts to escape led to all kinds of problems between themselves, the Korean authorities, and the Manchus when they got caught up in the dispute. There would be no way a non-Asian time traveler would be able to operate in the bulk of East Asia without 'blowing their cover'. 



Ray McCarthy said:


> Vikings in Greenland 100% visited Canada. It's not so sure if Welsh and Irish really did, but certainly some stories suggest it.



That's great for a time-traveler who resembles (Or can pass for) a Viking/Irish/Welsh settler traveling to a time period when they are said to operate in that part of Canada. Any place elsewhere, any earlier (or later) time, and the time-traveler at minimum gets caught. Worst-case scenario the timeline gets wrecked when the studied group gets ahold of the (likely dead at this point) time traveler's equipment and weapons.


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## Ray McCarthy (Apr 2, 2016)

Old_Man_Steve2016 said:


> The Spanish Conquest of the Aztecs.


Completely different scenario to a lone traveller.
Also indigenous people assisted the Spanish. The Aztecs had fought a civil war, fought other wars and their Nation was under pressure.
The intention of the Spanish was to cause trouble and carry off gold. Though in the end it was silver that they seriously got. They did carry off a lot of gold.
Story of cities #6: how silver turned Potosí into 'the first city of capitalism'
from The story of cities | Cities | The Guardian

The North American Indians Indigenous peoples adopted horses from the Europeans. Trouble came later.



Old_Man_Steve2016 said:


> There would be no way a non-Asian time traveler would be able to operate in the bulk of East Asia without 'blowing their cover'.


Sure they would, they'd be prepared.

Marco Polo and many others did OK.
(It's a myth he brought back pasta from China, though he might have brought the idea of noodles, Italians already had pasta sheets.)


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## sinister42 (Apr 12, 2016)

Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.

Also, you can't kill Hitler, because you didn't.


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## BAYLOR (May 14, 2016)

I can just imagine finding myself in the court of King Henry the 8th.  I think


sinister42 said:


> Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.
> 
> Also, you can't kill Hitler, because you didn't.



You can do away with Hitler, what would likely happen is you would create an alternate timeline.


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## Dennis E. Taylor (May 15, 2016)

sinister42 said:


> Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.



Naw, it's not a problem. Observe! (waves hand)
Appearing in deep space has a couple of problems. First, it assumes an absolute reference frame, which Einstein assures us doesn't exist. Second, moving from deep in Earth's gravity well to deep space would required the same amount of energy as launching from the Earth to deep space. So it ain't gonna happen.

Instead, in the absence of an absolute frame, time travel occurs within the local frame, which is defined by constant gravitational potential. In other words, the Earth drags local time along with it, so you'll always end up on Earth. Also, angular momentum figures into it, so you'll also always end up on the same *part* of Earth.

(stops waving hand)

This example of handwavium brought to you by that Martian guy who wants to disintegrate things.


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## Charles Parkes (May 15, 2016)

sinister42 said:


> Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.
> 
> Also, you can't kill Hitler, because you didn't.



Ouch. You're really messing with my sequel storyboarding. Firstly - in fantasy, when you time-travel you don't pop out a million miles out in space where the world will be or had been because . . . magic.

Secondly, I'm pretty sure Quentin Tarantino already did go back in time and kill Hitler : ) so I think you must be some kind of time relic from the pre-inglorious basterds time-stream. You should be disappearing right about. . . . [pop]

[ - The whole WW2 historical fiction genre disappears, leaving men of my father's generation with nothing to do, and nothing to imagine that they'd would have been good at - had they been born into a different era whereupon they'd naturally been made an allied field marshal]


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## Dennis E. Taylor (May 15, 2016)

Charles Parkes said:


> [ - The whole WW2 historical fiction genre disappears, leaving men of my father's generation with nothing to do, and nothing to imagine that they'd would have been good at - had they been born into a different era whereupon they'd naturally been made an allied field marshal]



... in a fit of boredom, they form their own political party, which, strangely, uses the swastika as a symbol. They take over Canada, Mexico, and begin spreading across Central and South America, while eyeing Europe. Churchill makes a speech...


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## BAYLOR (May 15, 2016)

Charles Parkes said:


> Ouch. You're really messing with my sequel storyboarding. Firstly - in fantasy, when you time-travel you don't pop out a million miles out in space where the world will be or had been because . . . magic.
> 
> Secondly, I'm pretty sure Quentin Tarantino already did go back in time and kill Hitler : ) so I think you must be some kind of time relic from the pre-inglorious basterds time-stream. You should be disappearing right about. . . . [pop]
> 
> [ - The whole WW2 historical fiction genre disappears, leaving men of my father's generation with nothing to do, and nothing to imagine that they'd would have been good at - had they been born into a different era whereupon they'd naturally been made an allied field marshal]



In L Sprague de Camp novel * Lest Darkness Falls* . The main character  Martin Padway a  20th century man is whisked back to 6th century Rome via a lighting bolt.


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## sinister42 (May 15, 2016)

Bizmuth said:


> Naw, it's not a problem. Observe! (waves hand)
> Appearing in deep space has a couple of problems. First, it assumes an absolute reference frame, which Einstein assures us doesn't exist. Second, moving from deep in Earth's gravity well to deep space would required the same amount of energy as launching from the Earth to deep space. So it ain't gonna happen.
> 
> Instead, in the absence of an absolute frame, time travel occurs within the local frame, which is defined by constant gravitational potential. In other words, the Earth drags local time along with it, so you'll always end up on Earth. Also, angular momentum figures into it, so you'll also always end up on the same *part* of Earth.
> ...



Keanu Reeves saying "Whoa."


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## Vladd67 (May 16, 2016)

sinister42 said:


> Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.
> 
> Also, you can't kill Hitler, because you didn't.


Reminds me of this
Strontium Dog - Wikipedia, the free encyclopedia


> Like all Search/Destroy agents, Alpha is armed with highly advanced technology including a variable-cartridge blaster, electrified brass knuckles, a short-range teleporter, a "time drogue" that can briefly "rewind" the last few minutes of time, and "time bombs" which can transport somebody minutes or hours forwards or backwards in time (by which time the planet has moved along in its orbit, so that the victim reappears in empty space).


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## Kieran Song (May 28, 2016)

I can't live without my phone lol. I guess that'd completely compromise me.


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## Dave (May 28, 2016)

Kieran Song said:


> I can't live without my phone lol. I guess that'd completely compromise me.


We discussed smartphones earlier in this thread - obviously, you'd have no cell reception, GPS or internet to connect to - but as a calculator, stopwatch, clock, calendar, notebook and camera it would still be a fantastic tool. Games and songs could still be played. It should be possible to easily create some kind of battery to charge it as the materials and knowledge required are fairly low tech. I see all time travelling wizards consulting on their smart phones behind their curtains.

I do have a problem with the trope in time travel stories of putting an advertisement in the newspaper to send a message to the future to retrieve the time traveller. This might work for a Newspaper like _The Times_ of London (which has a great age and also copies have been kept and conserved.) It would not work for most Newspapers that lasted a few years or were very local. In recent years newspaper circulations have all but died. While many are available now digitally archived, a much larger number are not. Also, putting a advertisement in _The Times_ would be incredibly expensive, and alert all of the bad guys you were hiding from. Additionally, I have searched the online digital Times archive and cannot find any messages for time travellers to be brought back home.


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## Lew Rockwell Fan (May 28, 2016)

Dave said:


> Additionally, I have searched the online digital Times archive and cannot find any messages for time travellers to be brought back home.


That's because I used code.


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## galanx (May 28, 2016)

sinister42 said:


> Here's a real problem with time travel.  Unless your time machine can also calculate the orbit of the earth and its position in space at a given point in time, you're going to pop out of your time machine into the hard vacuum of space - cause the Earth moves, you know.
> .



Gregory Benford dealt with that in "Timescape"


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## Vertigo (May 28, 2016)

I don't see the big deal about charging any electronic devices you might take. There are plenty of very good solar chargers around now...


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## sinister42 (May 28, 2016)

Another theory of time travel I've been thinking about: What if you _just_ travel through time - i.e. you rewind your own life, and when you arrive 10 years ago, you're just...you 10 years ago?  Are you "you 10 years ago" with today's memories and experiences, or do you rewind those as well and just end up reliving the last 10 years exactly as they were?  If you change something, is there still a paradox?


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## Dave (May 28, 2016)

Kurt Vonnegut in _TimeQuake_ has exactly that; people reliving 10 years again. They can't change anything though, it happens just as before. So, they go into a kind of automatic pilot mode. This is a disaster when the 10 years is up and they have to begin to make choices again. Aircraft fall out of the sky because they no longer fly by themselves, cars crash because they no longer drive themselves.


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