A question for all you time travelers

[pelligrini]

I thought Mikey hated everything?
Except for that cereal in that commercial....

[woodturner]

Show me any case where Carbon dating has been used on a specimen that was not "once-living".

Here is a link that does a decent job of explaining the basics
http://www.thetartan.org/2009/2/23/s.../howthingswork

Carbon 14 dating can be used to "date" any material containing carbon-14. While living or once-living organisms are one significant class containing carbon-14, inanimate objects such as stone often do contain sufficient carbon-14 to allow "dating". In addition, non-living but organic substances (e.g. substances containing carbon) will usually produce some quantity of carbon-14 and thus can be "dated".

As a practical matter, carbon-14 dating is somewhat controversial in the field, due to the assumptions required to derive a date. As a result, a combination of methods is typically used in an effort to gain some confidence that the estimated age may be accurate. Or at least that's what we do in our lab and publications.

[woodturner]

Only as long as the carbon that was incorporated into the material came from an atmospheric source.

I disagree - we often "date" material containing Carbon-14 that did not come from atmospheric sources. For that matter, other isotopes can be used as well, it's just that carbon-14 is particularly convenient.

[tfischer]

Assuming the object was manufactured - i.e. did not exist in present form at some prior date - and you travelled back in time to before that prior date, the object would not exist. In other words, you could not transport it back to an earlier time.

That's not the way it works in most Sci-Fi. Look at "Back to the Future". He had a very real DeLorean Time Machine, plus all the clothes he was wearing (remember the "life preserver" comments, and the fact he was called "Calvin Klein"?) At the end of the first movie, they bring the "Mr. Fusion" back from the future, and the plot of the 2nd movie was based on the fact that Biff brought the sports score anthology back and won many bets off of it.

Granted BTTF isn't exactly the be-all-end-all of Time Travel, but I'm just sayin'...

[woodturner]

That's not the way it works in most Sci-Fi.


Granted BTTF isn't exactly the be-all-end-all of Time Travel, but I'm just sayin'...

That's why they call it science fiction ;-)

[tfischer]

That's why they call it science fiction ;-)

As noted above,it's all fiction until we figure it out for real

[woodturner]

As noted above,it's all fiction until we figure it out for real

True, true.

Of course, we are all time travellers - it's just that we only go forward, not backward.

It has been years since I was active in the high energy physics field, but at that time, we knew of only one type of particle that travelled backward in time - and it was annihilated at the speed of light. That seems to be the fundamental obstacle in current science to time travel and to travelling faster - an object with mass must be infinitely massive to travel at the speed of light.

[Wood_workur]

Assuming it is a once living object, I'd think that it'd be the age before you sent it back in time + the time back in time.

[docrowan]

I disagree - we often "date" material containing Carbon-14 that did not come from atmospheric sources. For that matter, other isotopes can be used as well, it's just that carbon-14 is particularly convenient.

How is Carbon 14 generated except by cosmic rays in the upper atmosphere, which is then mixed through the rest of the atmosphere through natural wind currents? With a half life of roughly 6,000 years and a detectable limit of approximately 60,000 years it has to be a constantly generated source to be of value in dating materials. And by other isotopes, do you mean other isotopes of carbon or are you referring to other elements?

[Mr__Bill]

You don't really have to travel the speed of light to time travel. You just side step into the time stream of a parallel universe where the time stream is traveling in the opposite direction of your time stream. Then step back when you reach your destination in time. The trick is to pick a universe where time is moving significantly faster than in your original universe. After all you don't want to spend 10,000 years to travel 10,000 back in time.

I was going to do that and post this at the start of the message thread but I expect that it would have just confused some.


Bill, who, when he figures out which day is summer on the Oregon Coast will just keep returning to that day.

[woodturner]

How is Carbon 14 generated except by cosmic rays in the upper atmosphere, which is then mixed through the rest of the atmosphere through natural wind currents?...And by other isotopes, do you mean other isotopes of carbon or are you referring to other elements?

While that is the source of the most prolific production of carbon 14, it is also a byproduct of other processes.

Other isotopes of carbon or any other material, really.

BTW, the wiki article contains a reasonable explanation of how "non-living" substances such as coal and rock are carbon dated.

[woodturner]

You don't really have to travel the speed of light to time travel. You just side step into the time stream of a parallel universe where the time stream is traveling in the opposite direction of your time stream. Then step back when you reach your destination in time.

Only two problems with that idea:
1. It requires the existence of parallel universies (which are a theory, but not a verified or accepted one)
2. It assumes the rate and direction of the passage of time is not related to speed (which conflicts with our current understanding of time)

;-)