What is Planck length?
The '''Planck length''' (<math>l_P</math>) is the smallest unit of length. It is calculated from three [[physical constant]]s: the [[speed of light]], the [[Planck constant]], and the [[gravitational constant]]. The length was established as a way to simplify many of the more fundamental equations — if equations are written in [[Planck units]], you can do away with many physical constants and not have to worry about dimensions. The Planck length does not have any precise physical significance, and it is a common misconception that it is the inherent “pixel size” or smallest possible length of the universe.<ref>{{Cite web|url=https://www.physicsforums.com/insights/hand-wavy-discussion-planck-length/|title=What Planck Length Is and It's Common Misconceptions|first=Alex|last=Klotz|date=9 September 2015|website=|publisher=|accessdate=}}</ref> If a length smaller than this is used in any measurement, then it has a chance of being wrong due to quantum uncertainty.<ref>{{Cite web|url=https://www.physicsforums.com/threads/is-it-possible-for-something-to-be-smaller-than-a-planck-length.970002/|title= Is it possible for something to be smaller than a Planck length?|first=|last=|date=11 April 2019|website=|publisher=Physics Forums: Science Discussion, Homework Help, Articles|accessdate=30 November 2023}}</ref> It is about {{val|1.616255|e=−35|u=m}} or about 10<sup>−20</sup> times the size of a [[proton]]. It is one of the [[Planck units]], defined by [[Max Planck]]. It is an important length for [[quantum gravity]] because it may be approximately the size of the smallest [[Black hole|black holes]].<ref>{{Cite web|url=http://math.ucr.edu/home/baez/planck/node2.html|title=The Planck Length|first=John|last=Baez|website=|publisher=|accessdate=}}</ref> The speed of light is also one Planck length per [[Planck time]]. If the universe were scaled down such that a quarter (the coin) was the size of a Planck length, then the entire observable universe would be about one-hundredth the width of a human hair. ==Related pages== * [[