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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Tachyonic antitelephone ： ウィキペディア英語版 Tachyonic antitelephone A tachyonic antitelephone is a hypothetical device in theoretical physics that could be used to send signals into one's own past. Albert Einstein in 1907 presented a thought experiment of how faster-than-light signals can lead to a paradox of causality, which was described by Einstein and Arnold Sommerfeld in 1910 as a means "to telegraph into the past". The same thought experiment was described by Richard Chace Tolman in 1917;〔 〕 thus, it is also known as Tolman's paradox. A device capable of "telegraphing into the past" was later also called a "tachyonic antitelephone" by Gregory Benford et al. According to the current understanding of physics, no such faster-than-light transfer of information is actually possible. For instance, the hypothetical tachyon particles which give the device its name do not exist even theoretically in the standard model of particle physics, due to tachyon condensation, and there is no experimental evidence that suggests that they might exist. The problem of detecting tachyons via causal contradictions was treated scientifically.〔 〕 ==One-way example== Tolman used the following variation of Einstein's thought experiment:〔〔 Imagine a distance with endpoints $A$ and $B$. Let a signal be sent from A propagating with velocity ''a'' towards B. All of this is measured in an inertial frame where the endpoints are at rest. The arrival at B is given by: :$\backslash Delta\; t=t\_-t\_=\backslash frac.$ Here, the event at A is the cause of the event at B. However, in the inertial frame moving with relative velocity ''v'', the time of arrival at B is given according to the Lorentz transformation: :$\backslash begin$ \Delta t' & =t'_-t'_=\frac}}}-\frac}}}\\ & =\frac/c^}}\Delta t. \end It can be easily shown that if ''a > c'', then certain values of ''v'' can make ''Δt' '' negative. In other words, the effect arises before the cause in this frame. Einstein (and similarly Tolman) concluded that this result contains in their view no logical contradiction; he said, however, it contradicts the totality of our experience so that the impossibility of ''a > c'' seems to be sufficiently proven.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tachyonic antitelephone」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.