Engineering

New 3D-printing method builds structures with two metals

Taking a cue from the structural complexity of trees and bones, Washington State University engineers have created a way to 3D-print two types of steel in the same circular layer using two welding machines. The resulting ...

Robotics

Mori3: A polygon shape-shifting robot for space travel

By combining inspiration from the digital world of polygon meshing and the biological world of swarm behavior, the Mori3 robot can morph from 2D triangles into almost any 3D object. The EPFL research, which has been published ...

Electronics & Semiconductors

Passive radiative cooling can now be controlled electrically

Energy-efficient ways of cooling buildings and vehicles will be required in a changing climate. Researchers at Linköping University have now shown that electrical tuning of passive radiative cooling can be used to control ...

Electronics & Semiconductors

Miniature and durable spectrometer for wearable applications

Researchers have developed a wafer-thin chip-scale spectrometer that is suitable for wearable applications. The robust gallium nitride lab-on-a-chip device can also withstand harsh environments with severe radiation, such ...

Hardware

Ultrathin solar cells promise improved satellite performance

Most space satellites are powered by photovoltaic cells that convert sunlight to electricity. Exposure to certain types of radiation present in orbit can damage the devices, degrading their performance and limiting their ...

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Space

Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of the boundless four-dimensional continuum known as spacetime. In mathematics spaces with different numbers of dimensions and with different underlying structures can be examined. The concept of space is considered to be of fundamental importance to an understanding of the universe although disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.

Many of the philosophical questions arose in the 17th century, during the early development of classical mechanics. In Isaac Newton's view, space was absolute - in the sense that it existed permanently and independently of whether there were any matter in the space. Other natural philosophers, notably Gottfried Leibniz, thought instead that space was a collection of relations between objects, given by their distance and direction from one another. In the 18th century, Immanuel Kant described space and time as elements of a systematic framework which humans use to structure their experience.

In the 19th and 20th centuries mathematicians began to examine non-Euclidean geometries, in which space can be said to be curved, rather than flat. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space. Experimental tests of general relativity have confirmed that non-Euclidean space provides a better model for explaining the existing laws of mechanics and optics.

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