There isn't a definitive answer to this question since there are many things that could be considered the slowest thing in the universe. However, some of the contenders for this title include light, electrons, and even time itself.
Light is often said to be the fastest thing in the universe, but it also has a very slow side. In fact, when it comes to speed, light is actually quite bipolar. It can travel at an incredibly fast pace â€“ so fast that it's hard for us to even wrap our minds around it â€“ but it can also move incredibly slowly.
For example, when light is traveling through a medium like water or glass, its speed slows down significantly. In fact, depending on the density of the medium through which light is traveling, its speed can decrease by up to 90%. This means that if you were somehow able to observe light moving through a dense medium like lead glass (which has a refractive index of 2.4), it would appear to be moving at just one-quarter of its normal speed!
So while light typically moves incredibly fast â€“ so fast that we usually don't even notice â€“ there are certain circumstances where it can appear quite sluggish indeed.
Electrons are another contender for slowest thing in the universe title. These subatomic particles are responsible for electrical conductivity and they typically move pretty quickly â€“ but again, there's a catch. When electrons are confined to a material like metal wire or semiconductor crystal lattice their movement can be severely restricted.
As electrons tryto move through these materials they bump into atoms and get scattered off course again and again until eventually they find an open space where they can continue on their way unimpeded once more . This process repeats over and over , making electron flow through these types of materials extremely sluggish . So while free - flowing electrons can zip along at high speeds , those that are confined within materials tend to crawl along much more slowly .
And finally , we come to time itself . Now , technically speaking , time isn't really a thing ; rather ,it's justa way of measuring change . Butfor all intentsand purposes , wecan consider time as being something akinto an invisible substancethat permeates everything in existence . And if that'sthe case then perhapsits movements couldbe consideredthe slowestof all .
After all , no matter howfast something maybe travellingâ€“ whetherit 'slightor anelectronor anything elseâ€“ eventuallyit will succumbto entropyand come grindingtoahalt as everythingin existenceeventually decaysinto nothingness