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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: sci.physics.relativity Subject: Re: Approximately 300,000 km/s With Respect To What? Date: Wed, 17 Jul 2024 13:27:52 +0300 Organization: - Lines: 64 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 17 Jul 2024 12:27:52 +0200 (CEST) Injection-Info: dont-email.me; posting-host="d92d20f87707bf0424e9a8a28e9f3d9b"; logging-data="1897034"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+WY9pQ3zrr0+WBEJHGk163" User-Agent: Unison/2.2 Cancel-Lock: sha1:evsvCBILX+NhcqK65+c3PMPzfec= Bytes: 3671 On 2024-07-16 07:26:07 +0000, Thomas Heger said: > Am Montag000015, 15.07.2024 um 11:05 schrieb Mikko: >> On 2024-07-15 06:26:42 +0000, Thomas Heger said: >> >>> Am Sonntag000014, 14.07.2024 um 12:19 schrieb Mikko: >>>> On 2024-07-13 08:08:44 +0000, Thomas Heger said: >>>> >>>>> Am Freitag000012, 12.07.2024 um 11:26 schrieb Mikko: >>>>>> On 2024-07-11 19:58:02 +0000, amirjf nin said: >>>>>> >>>>>>> Approximately 300,000 km/s with respect to what? >>>>>> >>>>>> Whenever the speec of something is measured it is measured with respect >>>>>> to someting else. The report should make clear what is the reference that >>>>>> is considered stationary. Usually it is the instruments used in the >>>>>> measurement, and usually but not always they are at rest with restpect to >>>>>> Earth surface at the place of the measurement. >>>>>> >>>>> >>>>> 'Stationary' can be understood as 'not moving' and that as 'having >>>>>  velocity zero'. >>>> >>>> Yes, that is what the word means. >>>> >>>>> But velocity would require a reference point, in respect to which the >>>>> object does not move. >>>> >>>> That gives you a revefernce point: the object does not move in respect to >>>> itself. >>>> >>> >>> Actually I have used this setting in my 'book' and declared, that all >>> observers regard themselves as non-moving. >> >> That is possible but not always the best idea. In the real world an observer >> often considers oneself as moving and someting else as stationary. Often >> it is better to choose samething inertial for "statinary" when the observer >> is not inertial. >> > Sure, but 'non-inertial observers' where not included in SRT. Not intentionally but SRT can be used for calculations of what a non-inertial observer would see. > IOW: there is no acceleration in SRT, but only streigth steady movement > in a force free space. There is. Acclerated motions can be described and analyzed with SRT. Electric and magnetic fields discussed in "On the Electrodynamics of Moving Bodies" are meaningful only by their affect on the acceleration of charged bodies. > The very word 'acceleration' was used by Einstein in 'On the > electrodynamics of moving bodies' only in connection with the electron > and not in any other relation. Because what at the time were called "electrons" were only bodies to which electrodynamics is obviously relevant. It was even speculated that all matter migh be only electrons (both positively and negatively charged so they would stick together). -- Mikko