Mendelive supported the presence of a lost element in the periodic table, with mass even less than hydrogen called the aether. Any theories supporting this or in favour of this ? And what are the theories against ? Do you think it can be real ? Also Nikola Tesla supported the presence of the aether, though he considered it more of a force.
Don't post the same stuff twice over in different threads. As far as chemistry goes, it is plain that "aether" could not be an element. Given that hydrogen has an atomic number of 1 and everything else is heavier than hydrogen, what would its atomic number be? Mendeleev died in 1907, before the modern conception of propagation of light and relativity were fully established. So what he may have thought about aether is irrelevant today, except as a historical curiosity, like phlogiston.