Overview of Shimano brands 2018: www.evanscycles.com/coffeestop/advice/the-complete-guide-to-shimanos-mountain-bike-groupsets-and-their-hierarchy
- Shimano Altus RD-M310: almost cheapest MTB
- Shimano Acera RD-M360: second cheapest MTB
- Shimano Alivio RD-M410: third cheapest MTB
- Shimano Claris: entry 8-speed road bike www.youtube.com/watch?v=6dFQDDg6Wt0
- Shimano Sora: 9-speed road bike bike.shimano.com/en-EU/product/component/sora-r3000.html
- Shimano Tiagra: 10-speed road bike bike.shimano.com/en-EU/product/component/tiagra-4700.html
- Shimano Deore: non-shitty MTB, in increasing performance: M610, M6000, M7000, ...)
- Shimano Tourney; commuter, likely the shittiest of all lines: bike.shimano.com/en-EU/product/component/tourney.html
Explains how it is possible that everyone observes the same speed of light, even if they are moving towards or opposite to the light!!!
This was first best observed by the Michelson-Morley experiment, which uses the movement of the Earth at different times of the year to try and detect differences in the speed of light.
This leads leads to the following conclusions:
- to length contraction and time dilation
- the speed of light is the maximum speed anything can reach
All of this goes of course completely against our daily Physics intuition.
The "special" in the name refers to the fact that it is a superset of general relativity, which also explains gravity in a single framework.
Since time and space get all messed up together, you have to be very careful to understand what it means to say "I observed this to happen over there at that time", otherwise you will go crazy. A good way to think about is this:
- use Einstein synchronization to setup a bunch of clocks for every position in your frame of reference
- on every point of space, you put a little detector which records events and the time of the event
- each detector can only detect events locally, i.e. events that happen very close to the detector
- then, after the event, the detectors can send a signal to you, who is sitting at the origin, telling you what they detected
Basically the opposite of reductionism.
Quotient of a subgroup H of G by a normal subgroup of the subgroup H.
That normal subgroup does not have have to be a normal subgroup of G.
As an overkill example, the happy family are subquotients of the monster group, but the monster group is simple.
The first really good quantum mechanics theory made compatible with special relativity was the Dirac equation.
And then came quantum electrodynamics to improve it: Dirac equation vs quantum electrodynamics.
TODO: does it use full blown QED, or just something intermediate?
www.youtube.com/watch?v=NtnsHtYYKf0 "Mercury and Relativity - Periodic Table of Videos" by Periodic Videos (2013). Doesn't give the key juicy details/intuition. Also mentioned on Wikipedia: en.wikipedia.org/wiki/Relativistic_quantum_chemistry#Mercury
Man-in-the-middle attack
quantumcomputing.stackexchange.com/questions/142/advantage-of-quantum-key-distribution-over-post-quantum-cryptography/25727#25727 Advantage of quantum key distribution over post-quantum cryptography has Ciro Santilli's comparison to classical encryption.
BB84 is a good first algorithm to look into.
Long story short:
- QKD allows you to generate shared keys without public-key cryptography. You can then use thses shared keys
- QKD requires authentication on a classical channel, exactly like a classical public-key cryptography forward secrecy would. The simplest way to do this is a with a pre-shared key, just like in classical public key cryptography. If that key is compromised at any point, your future messages can get man-in-the-middle'd, exactly like in classical cryptography.
QKD uses quantum mechanics stuff to allow sharing unsnoopable keys: you can detect any snooping and abort communication. Unsnoopability is guaranteed by the known laws of physics, up only to engineering imperfections.
Furthermore, it allows this key distribution without having to physically take a box by car somewhere: once the channel is established, e.g. optical fiber, you can just keep generating perfect keys from it. Otherwise it would be pointless, as you could just drive your one-time pad key every time.
However, the keys likely have a limited rate of generation, so you can't just one-time pad the entire message, except for small text messages. What you would then do is to use the shared key with symmetric encryption.
Therefore, this setup usually ultimately relies on the idea that we believe that symmetric encryption is safer than , even though there aren't mathematical safety proofs of either as of 2020.
Best ones:
- Change in your couch
- Put ketchup on fries
Political parties in the United States by 
Ciro Santilli 35 Updated 2025-01-06 +Created 1970-01-01
Ciro Santilli 35 Updated 2025-01-06 +Created 1970-01-01 There are unlisted articles, also show them or only show them.