For Book: How to Tell What Eon You're In

[Winemaker]

Regardless, he should take lots of temp, CO2 readings and pictures. Cuz if and when he gets back to normal time, he should have some proof of global cooling/warming.

Then your next book can be about his adventures while trying to avoid assassination by the dreamer/alarmists or the deniers.

[TromboneAl]

I've figured out a way he can get a clue: Erosion.

If he traveled back 65 million years, the rivers and hills near his location would be totally different. Yes, they'll be different, but not 65 million years different.

Maybe.

[jjquantz]

The stars actually do move fast enough to make the constellations noticeably different, take a look at the following:

And yes, I do know that the Big Dipper is an asterism, not a constellation. Image is from Big and Little Dippers: Everything you need to know | Favorite Star Patterns | EarthSky

For five more examples, see: http://news.discovery.com/space/hist...0000-years.htm

[TromboneAl]

Quote:

Originally Posted by jjquantz The stars actually do move fast enough to make the constellations noticeably different, take a look at the following: And yes, I do know that the Big Dipper is an asterism, not a constellation. Image is from Big and Little Dippers: Everything you need to know | Favorite Star Patterns | EarthSky For five more examples, see: What Will the Constellations Look Like in 50,000 Years? : Discovery News

That will work. He can notice that the big dipper looks about the same. Thanks.

[Winemaker]

I'm not so sure on your erosion theory. Here in winemaker country, the surface that we presently walk on is 65 million years old. Everything that was above us was eroded away into the Ohio/ Mississippi River valley over the ages to become the south.

[TromboneAl]

Well, the bluff near our house erodes back, on average, a foot per year:



So, in 65 million years, that's ... carry the one ... a lot!

[M Paquette]

Time traveling over millions of years? Don't forget to allow for the rise and subsidence of land, continental drift (*SPLASH*) and such.

Oh, and if your time travel machine doesn't have some means of adjusting it's position in space, a good spacesuit and supplies might be handy, just in case you come out where the Earth isn't. (Orbital motion of the Earth, movement of the Solar System through the galaxy, motion of the entire galaxy, cosmological inflation, etc)

[braumeister]

Quote:

Originally Posted by M Paquette if your time travel machine doesn't have some means of adjusting its position in space, a good spacesuit and supplies might be handy, just in case you come out where the Earth isn't.

One of the principal reasons I refuse to read anything involving time travel.

Almost exactly 100 years ago, Einstein knocked over that particular applecart by explaining that time only exists as part of the composite entity "spacetime" but that insight is still disregarded by most. Understandably, since the math is so fiendishly hard, but still ...