Then the speed of light was measured based on that length, which turned out to be 299792458 lengths of the bar per second. This was then used to redefine the meter to the distance light in vacuum travels in 1/299792458 seconds, so that the …

Why is the speed of light 299,792,458 m/s, and not (for instance) 3,1 or 4,3 x 10^44 m/s? The answer is that all those numbers are consequences of arbitrary choices of the units of measure. In fact there is nothing special about the number 299,792,458, so much so that one can correctly write that the speed of light is: 1079252848.8 [km/h] 0.3 ...

Why is the speed of light $299,792,458$ metres per second, and not faster or slower. Why not $500$ trillion kilometers per second or $120$ miles per hour? This has been 'bothering' me for a while.

2019年9月29日 · The speed of light is the speed at which lightwaves propagate through different materials. In particular, the value for the speed of light in a vacuum is now defined as exactly 299,792,458 metres per second. The meter is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second.

2014年1月10日 · The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time.

2015年8月11日 · This sounds very fast, and it is on a global scale. But if you look at the Universe on a larger scale than it sounds quite slow, For instance it takes light from one and of the Milky way 100,000 years to get to the other end. So something is causing the light to travel at a speed of no more than this 299,792,458 m/s.

2016年11月23日 · The number was chosen such that the speed of light (which was previously known to be approximately 299,792,458 m/s) will henceforth be exactly that number. Much detail on this can be found in this question and the associated answers. Note that that question asks the converse of this one - namely, "why does the speed of light have no uncertainty ...

2021年6月20日 · With the SI value of 299,792,458−m/s, the tolleranced value shown above corresponds closely as ...

2014年7月22日 · Q&A for active researchers, academics and students of physics. Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

2019年8月16日 · $\begingroup$ One might be more pedantic, and say that light travels at 299,792,458 m/s in any arbitrary EM radiation environment, but because light exhibits superposition, it's much easier to just say that it travels that fast in a perfect vacuum, and the superposition laws of light show that it will travel exactly the same speed in any EM environment.