Quora.com has started deleting some of my answers, so I will put them here for safe keeping.
What is the difference between general and special relativity?
Imagine that you have a pulsed laser beam connecting two, distant points on the Earth with femtosecond precision and accuracy.
Running alongside this laser beam is a pulsed electron beam and you measure the arrival-time of this electron beam relative to the laser beam with femtosecond accuracy using, for example, the optical synchronization system at the European XFEL (many years ago, I wrote my thesis on this).
When the moon pulls on the Earth’s crust, the laser beam system maintains a constant length and you measure changes in the arrival time of the electron beam relative to the laser beam. This represents a change in the distance the electrons traveled through the Earth.
Now, you change the momentum of the electron beam and notice that it also changes the apparent distance traveled through the Earth, but changing the momentum of the electron beam clearly didn’t change the Earth’s radius or gravitational pull, so how should we interpret this?
When the Earth’s radius increases, the Earth gets heavier. When the electron beam energy increases, it gets heavier.
There is a gravitational attraction between the relativistic electrons and the Earth and if we equate the local changes in gravity to the changes in the relativistic mass of the electrons, then g + delta g = (M+delta m) G/r^2 .
G=(g+delta g)/(M+delta m) * r^2 might be a new way to measure the gravitational constant, a value which has significant uncertainty of 10^-3
Invited Review Article: Measurements of the Newtonian constant of gravitation, G
The method I describe is comparable to those that measure G in a direction perpendicular to the surface of the Earth rather than parallel to the surface of the Earth.
J. P. Schwarz, Science 282, 2230–2234 (1998).
The sorts of gravitometers which are used in high-precision metrology have a resolution of about 2 micro Gal, while the measurement I’ve described has a resolution which is 1000 times better than this. A single, tidal oscillation measured by the XFEL optical synchronization system is
delta g = 75 +- 0.002 micro Gal
Such an experiment exposes the unusual semantics of special and general relativity. Whenever the Earth’s mass changes locally, the relativistic mass of the electrons has to be changed in direct proportion in order to keep the arrival-time of the electrons constant relative to the optical reference. If the optical reference is tuned to compensate for the change in the local gravitation, then the energy of the electrons will not be as stable relative to a more absolute reference provided by, for example, an atom impinged upon by synchrotron light from the electrons. This is an interesting situation because you have a trade-off between energy stability and arrival-time stability constrained by the uncertainty principle within a large scale accelerator and within a tiny atom.
If the equivalence principle holds, then mg = GmM/r^2, but in the instant that the electron beam’s energy increases, this equivalence principle is violated. That is why it is important to remember that general relativity is a static approximation of a more dynamic system.
When trying to capture the dynamic aspect of such a system, you need thecorrespondence principle instead. It says v dm/dt+mg=GMm/r^2 including a relativistic correction because F=ma is only true for low energy masses. Normally, the test mass cancels out and that is why all masses fall with the same acceleration – unless they are relativistic.
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How does this experiment compare to a gravitational wave experiment like LIGO? One would think that LIGO could measure optical path lengths with greater accuracy than the point-to-point optical synchronization system in the XFEL because LIGO measures one micron optical path-length changes with a precision of one part in 10^-21, after all. But this is not the case. LIGO only measures changes of one part in 10^-21 within a bandwidth of 10 Hz- 1000 Hz because the interstellar, cosmic, gravitational waves in which they are interested have relatively short wavelengths compared to the tidal, gravitational waves produced by the moon. Below 10 Hz, their apparatus has no accuracy whatsoever, while the femtosecond optical synchronization system at the European XFEL only works below 10 Hz and above 10000 Hz.
Calibration uncertainty for Advanced LIGO’s first and second observing runs
LIGO isn’t the only game in town, of course. Other groups use multiple, continuous wave laser sources in interferometry to measure arrival-time changes over relatively short distances. They can calibrate out humidity and temperature effects, but they can’t use this continuous wave technique over kilometers because of scattering in the fibers and because of discrepancies that build up in phase and group velocity when the power is too high.
In addition to the advantage of being able to send higher power signals without distortion, pulsed arrival time or interference measurement of optical signals instantiates the Fellgett advantage over a continuous wave interference measurement because a broadband source is multiplexed by default.
After a continuous wave (CW) upgrade, a direct comparison of the XFEL gravitational sensitivity with LIGO should be possible. In the meantime, there are smaller-scale experiments with atomic trap spectroscopy which have 10^-43 sensitivity. Given the proper laser frequency and rep-rate, they could offer a cross-check for LIGO results.
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Referring back to the original question: what is the difference between general and special relativity? The Sagnac loop tells us that light travels a shorter path in a circle when the circle rotates, but the Michelson interferometer tells us that light doesn’t travel a shorter path when it travels in a straight line that is mounted on a circle that rotates – unless the gravity or area of the circle is changing. The reason for this is that two points do not define a space, but three or more points do and contraction or expansion of light must be tied to a volume. The gravitational constant is given in units of volumetric expansion after all. This is why the distance between two points on the Earth, as measured with a laser, may be held constant, while the distance, as experienced by particles under the influence of gravity, may change as the shape of the planet changes.
Subtleties are important in this business and it is important to note that volumetric expansion can also be expressed as a localized vibration as when an object sinks within vibrating sand. This heuristic is not described by special or general relativity, but it is inherent in quantum mechanics. Joining the two formalisms requires an understanding of this.
How do I get more followers on Instagram?
We all know about how Amazon is filled with fake reviews, but how easy is it to become a fake “influencer”? From this video, I learned that after paying a service 200 Euro, a guy’s Instagram account went from 600 followers to 24000 followers within a few weeks and he was offered 2900 Euro by several companies that wanted him to help market their products. He could’ve been sued for fraud if he took the money, but it showed how easy the system is to scam.
The 200 Euro service did three things:
- 11,500 fake followers
- a ton of click farm likes
- 12,500 followers from a bot that went around following others and asking them to follow him (who knows how many of those followers were bots as well?)
An expert in online marketing was asked how many influencer accounts were affected by fake followers, he said, “All of them. Especially the big ones.” In a recent purge of fake, inactive accounts, celebrities like Kim Kardashian lost millions of followers in one day.
I’ve never used Instagram, but I do use Quora and wonder how many fake followers and bots are wandering around. I know I have some regular readers, but I have no way of knowing how genuine the view stats really are. It is possible to give a writer the illusion of distribution when there is none!
On Instagram, there are no drawbacks to having lots of followers because engagement is hard to quantify. But on a site like Quora, if a follower doesn’t interact with your content, scrolling through all of the text and liking, that counts against you and prevents your content from being distributed more widely.
My takeaway is that if you don’t like what someone writes, you could spend 20 bucks and get their account spammed with fake followers who produce downvotes or click patterns indicative of lack of interest. This could effectively prevent their words from spreading.
The war of ideas has been automated!
This is sad because we are all the victims. Readers are vulnerable to fake news and writers are vulnerable to marketing services which use questionable methods and metrics for success. I recently got an email from a well-known freelancing site. The headline was, “We will make you a rockstar!” and they were selling online marketing tools. As the sales rep for the tools, they may not know or need to know the dirty work behind the scenes, but this leads to the question: is a middleman for fraudulent or illegal activity liable in any way?
It used to be that such a narcissism enabling role was filled by a Rasputin or a Svengali, but today the character is AI and corporate.
This is my recipe for an internet rockstar:
- steal some work by a genius (maybe from Quora, Amazon, an old book in the library, or your mother’s romance novels from the 1970s)
- modify it just enough that stupid people or algorithms won’t see the similarity
- get editors, ghostwriters, and artists from a freelancing site to repackage it
- buy followers and likes and bots to promote your product
But how real is your success? I predict a backlash against this trend in which people start going out to see real people doing real things.
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This is getting long, so here is a link to two other answers that keep getting deleted:
https://kirstenhacker.wordpress.com/2019/08/05/the-fake-economies-of-the-internet/
https://kirstenhacker.wordpress.com/2019/08/27/neutron-nonsense/
https://kirstenhacker.wordpress.com/2019/08/11/monsters-in-our-midst/
Given that my private profile shows that I’ve written over 900 answers, when I view the profile from another account, I only have 800 answers. This means that around a hundred of my answers have been hidden from view — and I don’t know which ones they are!
That’s just how Quora works. I’m sure they have their reasons.
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I had a lengthy respite from deletions until two sprung up in October 2020
https://www.quora.com/Who-is-Naomi-Wolf/answer/Kirsten-Hacker
https://www.quora.com/What-is-Anderson-localization/answer/Kirsten-Hacker
I was accused of plagiarism and when quora investigated, they restored the answers.
Kirsten Hacker 
Hello, I like your thoughts on the matter, they are clear, refreshing and well developed, at the beginning. But at the end, I don’t understand your feelings or intentions, what’s your conclusion, or even opinion ? It seems you just feel bad about how media markets function, I don’t see what’s new with it, except the tools are evolving with IA.
Any inspiration had origins, so at which point do you qualify using ideas a steal ?
“- steal some work by a genius (maybe from Quora, Amazon, an old book in the library, or your mother’s romance novels from the 1970s)”
Aren’t breakthroughs made of an “endless” string of slight modifications ?
(“modify it just enough that stupid people or algorithms won’t see the similarity”)
And I mean, as you wrote, these egocentrics physicists succeeded and mastered their “art” (pickup artists and such). Let’s be clear, I don’t like or follow ego bound people at all. But if opinions are a matter of perspective, these people are geniuses in their respective businesses. Which makes me wonder about the intent of your recipe for an internet rockstar:
“get editors, ghostwriters, and artists from a freelancing site to repackage it”
-> yes it seems to be a bit easy put in this way, but it makes me think of audio mastering, you know, there are lot of people working from the first ideas to the finished production (playing, mixing, mastering, packaging, advertising…)
“buy followers and likes and bots to promote your product”
-> Alright, how is that different than buying advertising space ? The mean is different, but in the outcome is similar.
Please tell me you’re not just disappointed because you came to realize how difficult it is that you have to work not only as a writer, but also as your own publisher ? Because I really like your otherwise phylosophies 🙂
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Thank you for the comment! I’m disappointed by how the internet has warped people’s sense of ethics.
Buying bots and likes is dishonest advertising (fraud), getting a ghostwriter to repackage someone else’s novel is dishonest (racketeering, plagiarism, and fraud), claiming someone else’s work as your own after making slight modifications is dishonest (plagiarism), using a romance novel from the 1970s as a verbatim template for an updated version set in the present is dishonest (plagiarism). It is disappointing to me that people have forgotten these basic principles.
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And thank you for answering back. There will always be plagiarism and bad ethics in the mind of uneducated and misguided people, and if your purpose is to bring awareness out of it then I 100% agree, but the tone of your writing here is so frustrated to me that it becomes frustrating.
As far as I see, if you want a breakthrough of your work, and have your name recognized for it, in any case you have to fight for it. Patents and copyrights laws have long existed, it’s nothing new. I may sound naive, I don’t know you and all, but how can you find the power (and especially the health) to pursue a career in this business if you stay shaken by those realities ? I mean you can fight for your rights to recover the recognition of your name people stole from you, I hope you will, that is most legitimate, but what is important is that you are learning from these failures and so you will gain the potential strength needed for your current or future work to bloom.
Please when you write “I’m disappointed by how the internet has warped people’s sense of ethics.” it seems you get overwhelmed by a big assumptions. Signs and isolated impressions are no proof for weighting “people” sense of ethics. A balance has to be found, like it has always been.
It is not easy by any mean, but unless you want to be driven by disappointment, won’t you be more powerfully in flow with your creativity and purpose if you let go of the F**(%!n$ disappointment ? If you manage first to remain healthy, happy and optimistic in the LONG run, what matters ? it’s just my impressions. take care !
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I’m a retard at science. But why banjax any of this? What does it hurt? We live in odd times.
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There are people who think that their responsibility is to bear witness to invisible problems and quietly record them without fighting about them. I think Jehovah’s Witnesses are sort of like that and they recently got massacred in Hamburg. People who turn a blind eye cause everything to fall apart.
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Yes. Fair. I’m only used to seeing a different set of vairiables and algorithms in the press dance, is all.
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