Talk:955: Neutrinos

Explain xkcd: It's 'cause you're dumb.
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When the news about the neutrino speed thing first came out, all these people I knew were asking if everything they knew was wrong because of the new discovery, and panning me for not believing the word of god that is the scientific journal. I don't know how these people get through life blindly believing everything that they're told. Davidy²²[talk]

It actually isn't too hard to live like that. Fortunately for me, though, I didn't have all these people I know asking if everything they knew was wrong. Inversion? --Quicksilver (talk) 18:34, 17 August 2013 (UTC)

"...arguing with people and preaching caution is futile. Cueball realizes that it is more satisfying and profitable to place bets with them instead." Does anyone else notice the similarity between this sentiment and mortgage security? Instead of preaching caution in lending and trying to convince people that they shouldn't be taking on loans, hedge funds were created - much more satisfying and profitable. Sorry if this has nothing to do with the comic, it was just an observation that struck me. -naginalf108.162.216.40 19:58, 11 March 2014 (UTC) (talk) (please sign your comments with ~~~~)

The discussion on this page is incorrect. Relativity does not say that nothing can travel faster than the speed of light, it says that objects with mass cannot travel at the speed of light. Massive objects can either travel below or above the speed of light. (talk) (please sign your comments with ~~~~)

Not as I read the wiki page on this: Upper limit on speeds. Maybe if you could have negative mass could you travel faster than c. But according to the page, nothing with zero mass or any finite (positive) mass can move faster than c. And yes if it has mass, then the speed will have to be sharply smaller than c. (But can get as close to c as you like by pouring in more energy).--Kynde (talk) 14:15, 30 September 2015 (UTC)

It is actually that you can't accelerate to the speed of light if you're already going faster you won't automatically have a immeasurable speed that is almost C you will keep going at that speed theoretically. 07:38, 22 September 2016 (UTC)

Cueball mentions Galileo. Is it because he went against the then-consensus on scientific knowledge and was punished, and others are accusing Cueball (and other "thought police") of attempting to do the same thing? 11:35, 12 November 2016 (UTC)

Could someone explain to me why a GPS wouldn’t work if relativity didn’t exist? (talk) (please sign your comments with ~~~~)

This is a good read. 06:43, 13 September 2018 (UTC)
It is a good read. To summarize the main points of that article:
  • GPS satellites contain atomic clocks to keep time, and they broadcast their current time. A GPS receiver measures the amount of time it took for the signals to arrive from the satellites' known positions, using trilateration to determine the receiver's position. (This is different from triangulation, which determines position by measuring angles.)
  • GPS satellites orbit at a speed of 14,000 km/h relative to Earth's surface. One effect of this is velocity time dilation: time passes slower for GPS satellites than it does near Earth's surface, drifting 7 microseconds behind, every day.
  • GPS satellites orbit at an altitude of 20,000 km, which is far enough away from Earth's mass that spacetime curvature is different there. One effect of this is gravitational time dilation: time passes faster for GPS satellites than it does near Earth's surface, drifting 45 microseconds ahead, every day.
  • Combining those, time passes faster for GPS satellites, by a net 38 microseconds (10-6) every day, relative to near Earth's surface.
  • But GPS precision depends on nanosecond-range accuracy (10-9), so 38,000 nanoseconds drift would cause GPS precision to accumulate an additional 10 km of error every day. GPS would still function – the satellites would still transmit, and the receivers would still calculate a position – but that position could be out by miles and miles; so if the purpose of GPS is to provide a reasonably precise position, then by that standard, GPS wouldn't work.
  • Albert Einstein's theories of special relativity and general relativity enable GPS to predict velocity time dilation and gravitational time dilation (respectively), and thereby compensate for the error so that GPS can work!
Yfmcpxpj (talk) 21:58, 5 September 2020 (UTC)
I'm sorry, but to me, your summary seems to make it sound like relativity is a problem that we are correcting for, rather than enabling anything. If relativity didn't exist, we wouldn't need to correct for velocity and gravitational time dilation. Mind you, that's only what I get from your summary, haven't actually read the article.-- 22:35, 24 March 2023 (UTC)
If Einstein's theories of relativity weren't correct, then we wouldn't have been able to use them to calculate how much correction is needed for GPS satellites to account for velocity and gravitational time dilation, but we did, and GPS does work, hence those theories relativity are supported. (talk) 19:42, 25 May 2024 (please sign your comments with ~~~~)
When initially launched, GPS satellites had both General Relativity and Special Relativity as optional built-in adjustments, that could be switched off if they actually weren't a factor (i.e. if the assumed 'corrections' made them wrong). But they soon found that they didn't need to not adjust for these effects and we live happily with them. (Certainly more happy than we would without!) 21:21, 25 May 2024 (UTC)