Nowadays that there is no Techeiless: Incidentally, when asked about wearing Techelet made from the Murex trunculus, the Rebbe, responded in Igros Kodesh 17/232 [printed in Shulchan Menachem 1/45] that he had nothing to add to the response of the Rebbe Rashab, on the question. The Rebbe Rashab was asked (circa 1907) specifically about the Radziner Techeiles discovered by the Radziner Rebbe Gershon Henoch Leiner in Poland which was from the cuttlefish. And in the year 1889, wrote a Halachic responsa [Eiyn Hatecheiles] acclaiming to have found the identity of the Techeiles carrying fish. The Rashab said that as much as he wanted to be able to say the Radziner Techeiles was legitimate, he could not after reading everything the Radziner Rebbe had provided him about it. Especially as the Ari z"l says that the the 'shefa' that is drawn into the world through the mitzvah of Techeiles would not be possible until the coming of Moshiach. [Sefer Divrei Shalom - Minhagei Rashash]. Chazal say that whoever wears "imitation" Techeiles, in other words not the real thing, is actually sinning (Bava Metzia 61b). Chazal also state that the early Chazal, hid, the Chilazon, implying until Moshiach.
[As the Rebbe Rashab has clarified in a famous letter: The fact that there is no Techeiles today is explained in the writings of the Arizal according to Kabbalah]. In which case ultimately even Korach would agree that today it is not possible to have a four cornered garment without Tzitzis.
