Episode #125 of the Stack Overflow podcast is here. We talk Tilde Club and mechanical keyboards. Listen now

 2 added 255 characters in body edited Jul 25 '14 at 7:32 Constandinos Damalas 5,03022 gold badges1111 silver badges3131 bronze badges I can always choose units where $$c = 1$$. This is almost always done in context of General Relativity, Special Relativity and Quantum Field Theory. As ACuriousMind said in the comments above, how we measure quantities tells us nothing useful about the physics of it, since units can be rescaled. In a way, every constant can be constructed from the 3 fundamental constants of nature which are: The speed of light $$c$$, The gravitational constant $$G$$, Planck's constant $$\hbar$$. As of why the speed of light is in the order of $$10^8$$? In my eyes, it is simply because compared to ordinary speeds where humans are used to, the speed of light is simply almost $$10^8$$ greater! Edit: You have asked in the comments why human speeds are so small compared to $$c$$. Well recall that the speed of light is the speed a massless particle travels through the universe. For massive particles you need energy to accelerate them close to c. Humans are a collection of massive particles and hence you require a lot of energy to accelerate them at those high speeds. That energy is way too high than what we extract out of food/fuel etc. I can always choose units where $$c = 1$$. This is almost always done in context of General Relativity, Special Relativity and Quantum Field Theory. As ACuriousMind said in the comments above, how we measure quantities tells us nothing useful about the physics of it, since units can be rescaled. In a way, every constant can be constructed from the 3 fundamental constants of nature which are: The speed of light $$c$$, The gravitational constant $$G$$, Planck's constant $$\hbar$$. As of why the speed of light is in the order of $$10^8$$? In my eyes, it is simply because compared to ordinary speeds where humans are used to, the speed of light is simply almost $$10^8$$ greater! I can always choose units where $$c = 1$$. This is almost always done in context of General Relativity, Special Relativity and Quantum Field Theory. As ACuriousMind said in the comments above, how we measure quantities tells us nothing useful about the physics of it, since units can be rescaled. As of why the speed of light is in the order of $$10^8$$? In my eyes, it is simply because compared to ordinary speeds where humans are used to, the speed of light is simply almost $$10^8$$ greater! Edit: You have asked in the comments why human speeds are so small compared to $$c$$. Well recall that the speed of light is the speed a massless particle travels through the universe. For massive particles you need energy to accelerate them close to c. Humans are a collection of massive particles and hence you require a lot of energy to accelerate them at those high speeds. That energy is way too high than what we extract out of food/fuel etc. 1 answered Jul 22 '14 at 10:21 Constandinos Damalas 5,03022 gold badges1111 silver badges3131 bronze badges I can always choose units where $$c = 1$$. This is almost always done in context of General Relativity, Special Relativity and Quantum Field Theory. As ACuriousMind said in the comments above, how we measure quantities tells us nothing useful about the physics of it, since units can be rescaled. In a way, every constant can be constructed from the 3 fundamental constants of nature which are: The speed of light $$c$$, The gravitational constant $$G$$, Planck's constant $$\hbar$$. As of why the speed of light is in the order of $$10^8$$? In my eyes, it is simply because compared to ordinary speeds where humans are used to, the speed of light is simply almost $$10^8$$ greater!