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Why are length contraction and time dilation not noticeable in everyday life?

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Brian Greene sits in a living room, holding a pen, with handwritten equations m = E/c^2 and E = mc^2 on a whiteboard beside him, highlighting c^2 as the speed of light. — relativity Brian Greene kicking off his *Your Daily Equation* video series with Albert Einstein's famous equation E = mc².

In the theory of special relativity, phenomena such as length contraction and time dilation are not noticeable in everyday life because they only become significant at speeds approaching the speed of light ( $c$ ).12

These effects are governed by the factor $\frac{v^{2}}{c^{2}}$ , where $v$ is the relative velocity of the observer and the object. In our daily experiences, the speeds we encounter are extremely small compared to the speed of light (approximately 300,000 kilometers per second). Consequently, the value of $\frac{v^{2}}{c^{2}}$ is minute, making Einstein’s relativistic equations virtually identical to the classical equations used in everyday life.2

While these effects are imperceptible in common activities, they are measurable through highly sensitive instrumentation or by observing elementary particles moving at high velocities. For instance, scientists have confirmed time dilation by comparing atomic clocks on Earth with those flown on high-speed aircraft, as well as through the behavior of muons in the atmosphere.31