Google Earth In 4D

Rockgod writes to tell us about Google Earth's latest expansion. From the article: "Google skipped right past the third dimension and landed directly in the fourth (time) by offering historical maps on Google Earth. Now you can travel back in time — for example, I am looking at the globe of 1790. Don't expect detailed high resolution photography from days gone by, but it's still interesting to see old maps overlaid on the satellite imagery of today." I suppose a link to Earth4 would have been good.

Comments

Pangea?

[Ingolfke]

Where's pangea? Come on Google... get with the program.

today's maps will be historical

[Speare]

I was thinking the other day about this. As new photos become available on Google Earth, the old ones will be removed... or pushed back in time, just like a CVS repository. A hundred years from now, you'd be able to walk the repository backwards and watch the suburbs shrink, the global waters recede, the forests regrow and the ice shelves stitch themselves together. (No guarantees expressed or implied.) Of course, Google would be one of those stodgy old companies that you wonder why they didn't implode in the nanostock scandals of 2065, but I digress.

A link to Google Earth would have been useful

[Anonymous Coward]

http://earth.google.com/earth4.html

4th Spacial Dimension

[onyx00]

I would have been more impressed if Google had been able to achieve the 4th spacial dimension.

Come on Google, I thought you guys were "innovators"

Re:4th Spacial Dimension

[MountainMan101]

They couldn't. The 4th spacial dimension is encumbered with patent rights. Only Microsoft and/or Novell customers can use it.

Hah!

[MyLongNickName]

I tried to go back to 7000 BC, and didn't see anything. You scientist types can try to explain this one away, but we all know what it REALLY means.

Re:Hah!

[ronanbear]

Yeah. The Flying Spaghetti Monster was obscuring the camera as a practical joke on creationists.

Re:The fourth dimension has nothing to do with tim

[Per Abrahamsen]

> The fourth dimension has nothing to do with time. It's another plane that intersects X, Y, and Z.

Usually denoted "t"... :-)

Re:If it's not spatial it's not 4D

[chrisb33]

While I agree that 4D is being used more as a buzzword than anything else, time is in fact considered as a fourth dimension in physics. You can look at special relativity if you want to understand how time and the spatial dimensions can be "interchanged":

In the geometry of special relativity, a fourth dimension, time, is added, with units of c, so that the equation for the differential of distance becomes:
ds^2 = dx_1^2 + dx_2^2 + dx_3^2 - c^2 dt^2
If we wished to make the time coordinate look like the space coordinates, we could treat time as imaginary: x4 = ict . In this case the above equation becomes symmetric:
ds^2 = dx_1^2 + dx_2^2 + dx_3^2 + dx_4^2

Special relativity goes on to say that you can exchange time and spatial coordinates using the Lorentz transform, which preserves the length of the 4D position vector.

If the special relativity example seems too bizarre, just think in terms of locating an event. If I wanted you to come to my party, I would tell you 4 pieces of info - the x,y,z, and t coordinates of the party. Each of these degrees of freedom is a dimension.


What's much more annoying to me are the "4D" shows that are 3D plus some user interaction (getting water shot at you or something like this). That is a misuse of "4D".