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Path: ...!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: hitlong@yahoo.com (gharnagel) Newsgroups: sci.physics.relativity Subject: A discussion of 'Tachyons, the 4-momentum ...' Date: Thu, 3 Oct 2024 10:10:06 +0000 Organization: novaBBS Message-ID: <7b7801803ba85c52030404bcf149487d@www.novabbs.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Info: i2pn2.org; logging-data="372690"; mail-complaints-to="usenet@i2pn2.org"; posting-account="TRF929uvrTGZYJLF+N3tVBXNVfr/PeoSjsJ9hd5hWzo"; User-Agent: Rocksolid Light X-Rslight-Site: $2y$10$09BWz7q3mn.6koZvnJUu0.3GYcojnUPCRFxtM6wdNYmLc5OskLMPy X-Rslight-Posting-User: cefb4c33981645a229d345bae7bb8942e6b32c35 X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 2174 Lines: 30 In DOI: 10.13189/ujpa.2023.170101, Figure 4 depicts a thought experiment involving FTL communication. This figure is attached to this post. We, the viewers, are at rest with observers A and B. At event E1, observer A, at x = 0, t = vL/c^2, sends an infinitely-fast tachyon signal to observer B, who receives it at x = L, t = vL/c^2. B immediately passes it to D, who is moving at velocity v. D's clock reads t' = 0. D is now going to send it to C. The question is, where is C? Is C at x = 0 or is C at x = Lv^2/c^2? According to us (the viewers), C is at x = Lv^2/c^2, but if we (the viewers) switched frames so we're at rest with C and D, (see Figure 5 in DOI: 10.13189/ujpa.2023.170101). Now, it appears that D can send a signal to c at t' = t = 0 (infinitely-fast). But according to our (the viewers) present position in Figure 5, A (at t = 0) could only send the original signal to B, who would receive it at t = vL/c^2, or the loop would not be completed (because of the relativity of simultaneity). Let's move back to Figure 4. So in order to complete the loop, D must send the signal to where C is not (at t = 0, x = 0), which flouts RoS. But at t = vL/c^2, C is not adjacent to A, so no closed loop can be completed in this scenario. Comments, Prok?