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This is an accepted version of this page This is the latest accepted revision, reviewed on 18 September 2024. Portable Document Format, a digital file format For other uses, see PDF (disambiguation). Portable Document Format Adobe PDF icon Filename extension.pdf Internet media type application/pdf, application/x-pdf application/x-bzpdf application/x-gzpdf Type code PDF (including a single ...
There have been three human eras so far, based on foraging, farming, and industry. The next era is likely to arise from artificial intelligence in the form of brain emulations, sometime in the next century or so. This book paints a detailed picture of this new era. — The Age of Em. The book's main scenario proposes that in about a hundred ...
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, [1] that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin -based chlorophyll, making the surface biosphere appear purplish ...
World map. A world map is a map of most or all of the surface of Earth. World maps, because of their scale, must deal with the problem of projection. Maps rendered in two dimensions by necessity distort the display of the three-dimensional surface of the Earth. While this is true of any map, these distortions reach extremes in a world map.
Stereoscopy creates the illusion of three-dimensional depth from a pair of two-dimensional images. [5] Human vision, including the perception of depth, is a complex process, which only begins with the acquisition of visual information taken in through the eyes; much processing ensues within the brain, as it strives to make sense of the raw information.
The earliest known life forms on Earth may be as old as 4.1 billion years (or Ga) according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. [2] The earliest evidence of life found in a stratigraphic unit, not just a single mineral grain, is the 3.7 Ga metasedimentary rocks containing ...
An aerial view of the city of Pori, Finland. Air photo of a military target used to evaluate the effect of bombing. Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. [1] When taking motion pictures, it is also known as aerial videography.