Dementors are among the foulest creatures that walk this earth. They infest the darkest, filthiest places, they glory in decay and despair, they drain peace, hope, and happiness out of the air around them. Even Muggles feel their presence, though they can't see them. Get too near a Dementor and every good feeling, every happy memory will be sucked out of you. If it can, the Dementor will feed on you long enough to reduce you to something like itself "" soul-less and evil. You'll be left with nothing but the worst experiences of your life.
J. K. Rowling
Most Muggles lived in a world defined by the limits of what you could do with cars and telephones. Even though Muggle physics explicitly permitted possibilities like molecular nanotechnology or the Penrose process for extracting energy from black holes, most people filed that away in the same section of their brain that stored fairy tales and history books, well away from their personal realities: Long ago and far away, ever so long ago.
He did not know or care whether they were wizards or Muggles, friends or foes; all he cared about was that a dark stain was spreading across Dobby's front, and that he had stretched out his thin arms to Harry with a look of supplication. Harry caught him and laid him sideways on the cool grass. "Dobby, no, don't die, don't die -" The elf's eyes found him, and his lips trembled with the effort to form words. "Harry... Potter... " And then with a little shudder the elf became quite still, and his eyes were nothing more than great glassy orbs, sprinkled with light from the stars they could not see.
He did not know or care whether they were wizards or Muggles, friends or foes; all he cared about was that a dark stain was spreading across Dobby's front, and that he had stretched out his thin arms to Harry with a look of supplication. Harry caught him and laid him sideways on the cool grass. "Dobby, no, don't die, don't die -" The elf's eyes found him, and his lips trembled with the effort to form words. "Harry...Potter..." And then with a little shudder the elf became quite still, and his eyes were nothing more than great glassy orbs, sprinkled with light from the stars they could not see.
J. K. Rowling