Gravitational field - gravitational field

The space in which gravity acts. A quantity called potential was introduced as a function to describe the action of gravity, which acts beyond the vacuum of space, and this was later developed into the concept of the gravitational field. Gravitational potential is a quantity that specifies the force that an object, which is the source of gravity, exerts on an object at another position as a function of position. For example, the potential of a sphere of mass M is inversely proportional to the distance from the center, and proportional to M and Newton's gravitational constant. Thus, the gravitational field in Newton's theory of gravity is merely an auxiliary means of describing forces, but the gravitational field in the theory of general relativity is a physical entity that contains energy, just like electric and magnetic fields. The propagation of energy in the gravitational field is gravitational waves. The gravitational field is also related to the metric of time and space, and creates a space-time structure with curvature. From the perspective of the unified theory of forces (unified field theory), the gravitational field can be considered as a gauge field that originates from the symmetry of space-time.

[Fumitake Sato]

"Theory of Relativistic Gravitational Fields," edited by Uchiyama Tatsuo (1975, Physical Society of Japan)" ▽ "Classical and Quantum Gravity Theory," written by Kimura Toshie and Ota Tadayuki (1989, McGraw-Hill Publishing)" ▽ "Fields and Space-Time," written by Nakanishi Masashi (1992, Nippon Hyoronsha)" ▽ "Introduction to Gauge Quantum Gravitational Field Theory," written by Suzuki Motoji (1993, Current Affairs Analysis Workshop)" ▽ "Theory of Relativity," written by Kubota Takahiro and Sasaki Takashi (2001, Shokabo Publishing)" ▽ "The Frontiers of Modern Physics 5," edited by Otsuki Yoshihiko, written by Bando Masako, Nakano Hiroaki, Furusawa Akira, Amaya Kiichi, and Onodera Akifumi (2001, Kyoritsu Shuppan Publishing)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

重力が作用する空間。真空の空間を飛び越えて重力が働くという引力の作用を記述するための関数として、ポテンシャルという量が導入され、のちにこれが重力場の概念に発展した。重力ポテンシャルとは、重力の源である物体が他の位置にある物体に及ぼす力を、あらかじめ位置の関数として指定しておく量である。たとえば質量Mの球体のポテンシャルは、その中心からの距離に反比例し、Mとニュートン重力定数に比例する。このようにニュートン重力理論における重力場は、力を記述する補助手段にすぎないが、一般相対性理論における重力場は、電場、磁場と同じくエネルギーを伴った物理実体である。そして重力場のエネルギーの伝播(でんぱ)が重力波である。また重力場は時間・空間の計量と関係し、曲率をもった時空構造をつくりだす。力の統一理論（統一場理論）の観点からみると、重力場は時空の対称性に由来するゲージ場であるとみなすことができる。

［佐藤文隆］

『内山龍雄編『相対論的重力場の理論』（1975・日本物理学会）』▽『木村利栄・太田忠之著『古典および量子重力理論』（1989・マグロウヒル出版）』▽『中西襄著『場と時空』（1992・日本評論社）』▽『鈴木基司著『ゲージ量子重力場理論入門』（1993・時事問題解析工房）』▽『窪田高弘・佐々木隆著『相対性理論』（2001・裳華房）』▽『大槻義彦編、坂東昌子・中野博章・古沢明・天谷喜一・小野寺昭史著『現代物理最前線5』（2001・共立出版）』

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