The Speed of Light Has Been Accurately Measured...Many, Many Times.

Brian’s Logic claims “The Speed of Light was Never Measured”.

Well, I guess laser measurement devices know something the rest of us don’t. The reality is that everyday real-world devices like laser measurement devices.

Oh, and Brian, Veritasium never said we don’t actually know the speed of light so stop misrepresenting his video as something debunking Einstein.

Veritasium: Why No One Has Measured The Speed Of Light

United States Patent No.: US 7,304,727 B2
Laser Distance-Measuring Device

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Baumer Performance laser distance sensors

[WalterBislin]

We can only measure the 2-way speed of light directly (as far as I know). But we can be certain, that the speed of light in vacuum does not depend on the direction, so the 1-way speed of light is the same as the 2-way speed of light. How can we be certain about this?

According to Maxwells equations the speed of light is the invariant c = 1 / √(ε₀ μ₀) where ε₀ = vacuum permittivity and μ₀ = vacuum permeability, which both are scalars and constants.

A scalar can not depend on direction, it’s not a vector. So if Maxwells equations are correct, then the speed of light in vacuum can not depend on the direction, so the 1-way speed of light must be the same as the 2-way speed of light.

This only assumes that Maxwells equations are right, which they are. Because if they were not right, we would not exists, because atoms are held together by forces that obey Maxwells equations.

And how would we calculate the energy output of a nuclear power plant, which is based on E = m c^2, and therefore correctly design all the systems involved, if we don’t know c for certain? 🤦🏻‍♂️

[superhornet]

I'm a telecommunications technician and even in the case of running cat5e/6/6a etc.. data cables, my $60 test device can tell me to the 1/10th of a metre how long the cable is by it having been programmed to know at what fraction of the speed of light the data transmission propagates through the cable ie for each cable it varies slightly such as 65%/69% etc.. of the speed of light.

[adventureswithdogs]

As someone born well before these measuring devices were first created, and even a bit before even the first lasers, I find these devices fascinating; even a bit incomprehensible. However, with just a little bit of research, it's easy to understand how they work.
And therein lies Brian's problem. He doesn't take that little bit of time to try to learn about these subjects. He, like most deniers, just picks a subject and runs with it.

[chrisdurhammusicchannel]

That seems a bit more edited!!! Great video!!!
Now we just need to measure the speed of Brian's Derp!!!

[oldtvnut]

The fact that we cannot by any method measure the difference in outgoing speed and return speed means that the difference is totally irrelevant in all physical situations/reality. We cannot and will not be able to find a situation in which inequality makes/would make a difference, and therefore we may assume equality as well as any degree of hypothetical inequality. The statement that we cannot measure the one way speed is exactly equivalent to saying that only the two way speed is relevant. That speed is always measured as C.

[farmersboy]

I know you have to lie to flerf, but denying we can use lasers to measure things when you can buy a laser measure (I have one) is just dumb. Really, really dumb.

[StringerNews]

Odd, when it comes to cars, the only way to win a speed record is to go that fast both ways. So why the arbitrary rule, Brian?

[eileendover]

My new kitchen was measured up using a laser. So cool.

[mymumbakescakes]

Brian's Logic proving yet again that he has no logic at all.

[scott_meyer]

If speed of light/EM, weren't the same in all directions, GPS would fail miserably.

[harryworp]

I've got a Bosch GLM30 laser measure. I just checked the accuracy — it's ±2 mm… which is probably better than I can do with a tape measure. 🤣

[scott_meyer]

The one way speed if light can be measured. However Relativity throws in a small error.

[flatearthphysics]

You cannot measure the speed of light anymore. It's exactly 299 792 458 m/s, or in other words, it takes exactly 127 / 1498962290000 seconds to travel one inch.

[nineoclockhero]

Oh Jezzz! Now I'm wondering what colour light travels fastest?, Why does yellow light turn orange when it hits a red object?, Does its speed change too?, Is it faster in a Hoover Or a Dyson? Turns off shower grabs

Oh No! I've been Brianated. 😄😄