We all move at the Speed of Light

ScienceClic English2 HN recommenders · 2020–2024
1.4M views · explainer · evergreen · Uploaded 2018-11-09

ScienceClic explains why nothing can go faster than light by treating motion through space and time together, so everything moves at the speed of light through spacetime. It uses animated visuals to cover relativity basics in 12 minutes.

HN commenters recommend it as a helpful way to conceptualize why light speed is a limit.

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4 comments from Hacker News

@karmakaze2020 · in “A Spacetime Surprise: Time Isn’t Just Another Dimension”

An interesting journey describing spacetime. > you can’t put space (which is a measurement of distance) and time (which is a measurement of, well, time) on the same footing without some way to convert one to the other. This idea about 'equal footing' is really a hazy way of asking if these dimensions can be considered 'independent', which the article then describes as being interdependent. > The key idea is that we’re all moving through the Universe, through both space and time, simultaneously. If we’re simply sitting here, stationary, and not moving through space at all, then we move through time at a very specific rate at which we’re all familiar: one second per second. This second/second rate is 'c' the speed of light, but through the 'time' dimension of spacetime. > However — and this is the key point — the faster you move through space, the slower you move through time. The other dimensions are not like this at all: your motion through the x dimension in space, for example, is completely independent of your motion through the y and z dimensions. This point is misleading. These dimensions are like time in that if I was traveling at the speed 'c' in only the x direction, then to move in y or z directions, movement in the x direction would need to be reduced. The main difference is that we're observing these x, y, z motions in non-relativistic scales but since 1 sec/sec is already 'c', any observation of change in motion through time is relativistic. > But your total motion

@danparsonson2021 · in “Positive Energy Warp Drive from Hidden Geometric Structures”

Try this: [VIDEO] c isn't defined as the speed of light - light travels at c, but so does everything else, when you factor in movement through time.

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@keithnz2021 · in “Very fast rocket”

you can't go faster. I know a lot of people find this video helpful in conceptualizing things. [VIDEO]

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@itishappy2024 · in “Time is a dimension, but not like space”

I've heard this described as "we all move at the speed of light." Also, since another way to describe alignment of two vectors is an angle, motion can be characterized by the angle it makes with the time axis. [VIDEO]