Many experiments intended to measure the one-way speed of light, or its variation with direction, have been (and occasionally still are) performed in which light follows a unidirectional path. Claims have been made that those experiments have measured the one-way speed of light independently of any clock synchronisation convention, but they have all been shown to actually measure the two-way speed, because they are consistent with generalized Lorentz transformations including synchronizations with different one-way speeds on the basis of isotropic two-way speed of light (see sections the one-way speed and generalized Lorentz transformations).These experiments also confirm agreement between clock synchronization by slow transport and Einstein synchronization. Even though some authors argued that this is sufficient to demonstrate the isotropy of the one-way speed of light, it has been shown that such experiments cannot, in any meaningful way, measure the (an)isotropy of the one way speed of light unless inertial frames and coordinates are defined from the outset so that space and time coordinates as well as slow clock-transport are described isotropically (see sections inertial frames and dynamics and the one-way speed). Regardless of those different interpretations, the observed agreement between those synchronization schemes is an important prediction of special relativity, because this requires that transported clocks undergo time dilation (which itself is synchronization dependent) when viewed from another frame (see sections Slow clock-transport and Non-standard synchronizations).
In the October 2009 issue of the American Journal of Physics Greaves, Rodriguez and Ruiz-Camacho reported a new method of measurement of the one-way speed of light. In the June 2013 issue of the American Journal of Physics Hankins, Rackson and Kim repeated the Greaves et al. experiment obtaining with greater accuracy the one way speed of light. This experiment proves with greater accuracy that the signal return path to the measuring device has a constant delay, independent of the end point of the light flight path, allowing measurement of the time of flight in a single direction.J. Finkelstein claimed that the Greaves et al. experiment actually measures the round trip (two-way) speed of light.In the November issue of the Indian Journal of Physics, Ahmed et al. published a comprehensive review of One-Way and Two-Way Experiments to test the isotropy of the speed of light.
It was argued against the conventionality of the one-way speed of light that this concept is closely related to dynamics, the laws of motion and inertial reference frames. Salmon described some variations of this argument using momentum conservation, from which it follows that two equal bodies at the same place which are equally accelerated in opposite directions, should move with the same one-way velocity. Similarly, Ohanian argued that inertial reference frames are defined so that Newton's laws of motion hold in first approximation. Therefore, since the laws of motion predict isotropic one-way speeds of moving bodies with equal acceleration, and because of the experiments demonstrating the equivalence between Einstein synchronization and slow clock-transport synchronization, it appears to be required and directly measured that the one-way speed of light is isotropic in inertial frames. Otherwise, both the concept of inertial reference frames and the laws of motion must be replaced by much more complicated ones involving anisotropic coordinates.However, it was shown by others that this is principally not in contradiction with the conventionality of the one-way speed of light. Salmon argued that momentum conservation in its standard form assumes isotropic one-way speed of moving bodies from the outset. So it involves practically the same convention as in the case of isotropic one-way speed of light, thus using this as an argument against light speed conventionality would be circular. And in response to Ohanian, both Macdonald and Martinez argued that even though the laws of physics become more complicated with non-standard synchrony, they still are a consistent way to describe the phenomena. They also argued that it's not necessary to define inertial frames in terms of Newton's laws of motion, because other methods are possible as well. In addition, Iyer and Prabhu distinguished between "isotropic inertial frames" with standard synchrony and "anisotropic inertial frames" with non-standard synchrony.
2014年、MLBドラフト1巡目（全体7位）でフィラデルフィア・フィリーズから指名され、6月12日に契約。契約後、傘下のA+級クリアウォーター・スレッシャーズでプロデビュー。AA級レディング・ファイティン・フィルズでもプレーし、この年は2球団合計で12試合に登板して4勝3敗・防御率2.93の成績を残した。2015年は開幕をAA級レディングで迎えた後、6月14日にはAAA級リーハイバレー・アイアンピッグスへ昇格。マイナー2球団合計では18試合に登板して10勝4敗、防御率2.39の成績を残し、同年のオールスター・フューチャーズゲームにも選出された。そして7月21日にメジャー初昇格を果たし、同日のタンパベイ・レイズ戦で先発してメジャー初登板。6回を1失点に抑えるも、打線の援護が無く敗戦投手となった（最終スコアは0 - 1）。次の登板の7月26日のシカゴ・カブス戦でメジャー初勝利を挙げた。この年メジャーでは13試合に登板し、6勝2敗、防御率3.59の成績を残した。2016年は一定のレベルで先発ローテーションに入り、20試合に先発登板した。6勝9敗、防御率4.78、WHIP1.31という成績に終わったが、FIPは4.04から3.08に改善し、投球内容が良くなったとも言える。また、高い三振奪取能力を発揮し、111.0イニングで121奪三振を記録・奪三振率9.8という好数値をマークした。2017年は序盤こそ良くなかったものの、その後は復調し、6月22日から8月12日の間は毎回6投球回以上、2失点以下の好投ぶりを見せた。最終成績は12勝11敗、防御率3.54で、奪三振率9.857、3.755奪三振/四球など指標面でも優秀な数字を残した。また、守備面では守備率1.000を記録。2018年は飛躍の年となった。前半戦を12勝3敗、防御率2.30の好成績で折り返し、初めてオールスターに選出された。後半戦も勢いは衰えず、最終的に33先発で212.1回（リーグ3位）を投げ、17勝6敗、防御率2.37（同2位）、WHIP0.97（同3位）、224奪三振を記録。ゴロ率（50.6%）と対左打者被打率（.187）はリーグ2位だった。サイ・ヤング賞投票で3位に入った。2019年2月13日に球団と4年4500万ドルの契約延長で合意した。5年目はクラブ側が選択権を持っている。シーズンでは開幕投手を務め、勝利した。