Changes

Some fields of [[science]] see nature as matter in motion, obeying certain laws of nature which science seeks to understand. For this reason the most fundamental science is generally understood to be "[[physics]]"—the name for which is still recognizable as meaning that it is the study of nature.  

Some fields of [[science]] see nature as matter in motion, obeying certain laws of nature which science seeks to understand. For this reason the most fundamental science is generally understood to be "[[physics]]"—the name for which is still recognizable as meaning that it is the study of nature.  

Matter is commonly defined as the substance of which physical objects are composed. It constitutes the [[observable universe]]. According to the theory of [[special relativity]], there is no unchangeable distinction between matter and [[energy]], because matter can be converted to energy (see [[annihilation]]), and vice versa (see [[matter creation]]).  The visible components of the universe are now believed to compose only 4 percent of the total mass. The remainder is believed to consist of 23 percent cold [[dark matter]] and 73 percent [[dark energy]].<ref>{{cite web |url=http://map.gsfc.nasa.gov/m_mm/mr_limits.html |title=Some Theories Win, Some Lose |work=[[WMAP]] Mission: First Year Results |publisher=[[NASA]] |accessmonthday=29|accessyear=2006 }}</ref> The exact nature of these components is still unknown and is currently under intensive investigation by physicists.

Matter is commonly defined as the substance of which physical objects are composed. It constitutes the [[observable universe]]. According to the theory of [[special relativity]], there is no unchangeable distinction between matter and [[energy]], because matter can be converted to energy (see [[annihilation]]), and vice versa (see [[matter creation]]).  The visible components of the universe are now believed to compose only 4 percent of the total mass. The remainder is believed to consist of 23 percent cold [[dark matter]] and 73 percent [[dark energy]].[http://map.gsfc.nasa.gov/m_mm/mr_limits.html] The exact nature of these components is still unknown and is currently under intensive investigation by physicists.

The behavior of matter and energy throughout the [[observable universe]] appears to follow well-defined [[physical law]]s. These laws have been employed to produce [[Physical cosmology|cosmological]] models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty [[physical constant]]s<ref>{{cite web | last = Taylor | first = Barry N. | year = 1971 | url = http://www.physics.nist.gov/cuu/Constants/introduction.html | title = Introduction to the constants for nonexperts | publisher = National Institute of Standards and Technology | accessdate = 2007-01-07

The behavior of matter and energy throughout the [[observable universe]] appears to follow well-defined [[physical law]]s. These laws have been employed to produce [[Physical cosmology|cosmological]] models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty [[physical constant]]s [http://www.physics.nist.gov/cuu/Constants/introduction.html] that appear to be static across the observable universe.[http://arxiv.org/abs/physics/0004062] The values of these constants have been carefully measured, but the reason for their specific values remains a mystery.

}}</ref> that appear to be static across the observable universe.<ref>{{cite journal | author=D. A. Varshalovich, A. Y. Potekhin, A. V. Ivanchik | title=Testing cosmological variability of fundamental constants | journal=AIP Conference Proceedings | year=2000 | volume=506 | pages=503 | url=http://arxiv.org/abs/physics/0004062 }}</ref> The values of these constants have been carefully measured, but the reason for their specific values remains a mystery.  

==Nature beyond Earth==

==Nature beyond Earth==