Weighing the Earth

Plate tectonics on early Earth? Weighing the paleomagnetic evidence

Paleomagnetism is the only quantitative method available to test for lateral motions by tectonic plates across the surface of ancient Earth. Here, we present several analyses of such motions using strict quality criteria from the global paleomagnetic database of pre–800 Ma rocks. Extensive surface motion of cratons can be documented confi dently to older than ca. 2775 Ma, but considering only t...

Weighing the Universe.

Weighing the Scales:

Political science provides two very different takes on how the information revolution affects the relationship between governments and global civil society. The more popular and prominent argument is that the Internet dramatically lowers the costs of networked communication; therefore, civil society groups are better able to mobilize action to influence governments. Countless numbers of article...

Weighing the deep continental biosphere.

There is abundant evidence for widespread microbial activity in deep continental fractures and aquifers, with important implications for biogeochemical cycling on Earth and the habitability of other planetary bodies. Whitman et al. (P Natl Acad Sci USA, 95, 1998, 6578) estimated a continental subsurface biomass on the order of 10(16) -10(17) g C. We reassess this value in the light of more rece...

Dynamic Weighing

In fabricating flowmeters, the meter's calibration is its final and accuracy determining step that comprises a great time consumption relative to its completion from its single component parts. Thus calibration (unless the respective time of calibration for a flow meter is not minimized) may represent a relevant contribution to fabrication costs. High-accuracy liquid flow calibration facilities...