The Speed of Light is NOT About Light
Why Hacker News recommends it
HN commenters send people to it whenever a thread confuses the speed of light with a light-specific limit, and several say it deepened their understanding of relativity.
What it is
PBS Space Time argues that the speed of light is better understood as the speed of causality, the universal limit on how fast cause and effect propagate. Light travels at that speed because it is massless, but the limit itself is a property of spacetime.
Recommended by 8 HN commenters across 8 different months, 2017 to 2023.
What Hacker News said
Strong rec willis936 · 2020-10 · on “NIST Pair of Atomic Clocks Reveal Einstein's Relativity at a Personal Scale”
PBS SpaceTime has a treatise on relativity. There are a dozen videos worth watching on this topic alone. The video about “the speed of causality” is the one that caused me to level up: [this video] Here is a 12 video playlist on relativity: [LINK] Here is a six video series on measuring space and time: [LINK]
Strong rec tzs · 2020-11 · on “Warp Drive News”
There's an episode of PBS Space Time about this, "The Speed of Light is NOT About Light" [1], which comes pretty close to making the same points you are making. It might be useful to watch this earlier episode, "Are Space and Time an Illusion?" [2], first. There is a later episode (or maybe a couple of them) that go into how interactions with the Higgs field make it so things with mass travel slowed than the speed of causality. To tie back to the warp drive news, they have an episode that would be a good place to start on warp drives, "Is The Alcubierre Warp Drive Possible?" [3]. There's also "Superluminal Time Travel + Time Warp Challenge Answer" [4], and "Will Wormholes Allow Fast Interste
Recommends neom · 2017-08 · on “Rumours swell over new kind of gravitational-wave sighting”
These PBS Spacetime episodes should help: The Speed of Light is NOT About Light - [this video] Is Quantum Tunneling Faster than Light? - [LINK] The Quantum Experiment that Broke Reality - [LINK] Pilot Wave Theory and Quantum Realism - [LINK] The Future of Gravitational Waves - [LINK]
Recommends stcredzero · 2018-02 · on “Speed of light drops to zero at 'exceptional points'”
Something to head off likely confusion: The Speed of Light is not about the Speed of Light. [this video] Don't get these two things mixed up: - The speed of electromagnetic waves in the local medium - The maximum speed our reality allows for causal phenomena
Recommends rhinokungfu · 2019-08 · on “Milky Way’s Black Hole Just Flared, Growing 75 Times as Bright for a Few Hours”
Speed of light is not really just speed of light, but universal speed limit of causality. Light (electromagnetic waves just happens to be one of the few things capable of hitting that limit. Even the effect of gravity is limited to speed of light. PBS Space time has a good video on this - [this video] . So to answer your question, no it is not possible for anything to affect us any faster than the universal speed limit of causality (that light happens to be able to hit).
Recommends dkersten · 2019-09 · on “Water found on a potentially life-friendly alien planet”
@mesid asked in a now dead comment: > What does speed of causality mean? And how is light so close to that? Take a look at this video by PBS Space Time on the topic: [this video] You may need to go down the rabbit hole and watch the earlier videos on relativity and related topics.
Recommends rhinokungfu · 2019-12 · on “If the universe is 13.8B years old, how can we see 46B light years away? (2018)”
Some of the confusion is, I think from referring to speed of light as "speed of light". When it really is speed limit of causality between 2 points in space. And light (em waves) just happen to be able to hit that limit. Now since expansion of space is itself not going to allow one point in space to cause any effect on another, it (the expansion) can be faster than speed of causality. PBS space time has a good video on this - [this video]
Recommends rhinokungfu · 2019-12 · on “If the universe is 13.8B years old, how can we see 46B light years away? (2018)”
Posted this to a point above, but probably more pertinent here, so reposting - Some of the confusion is, I think from referring to speed of light as "speed of light". When it really is speed limit of causality between 2 points in space. And light (em waves) just happen to be able to hit that limit. Now since expansion of space is itself not going to allow one point in space to cause any effect on another, it (the expansion) can be faster than speed of causality. PBS space time has a good video on this - [this video]