'What is the practical demarcation line of the prohibition against practicing magic (kishuf)?
There are two laws making use of the root kashaf that forbid sorcery: Shemoth 22:17 ('You shall not allow a sorceress to live') & Devarim 18:10-11 (' . . . not . . . among you . . . a sorcerer , . . .').
Bavli Sanhedrin 67a states very simply:
A SORCERER, IF HE ACTUALLY PERFORMS MAGIC, IS LIABLE [TO DEATH]. BUT NOT IF HE MERELY CREATES ILLUSIONS. R. AKIBA SAID IN R. JOSHUA'S NAME: OF TWO WHO GATHER CUCUMBERS [BY MAGIC] ONE MAY BE PUNISHED AND THE OTHER EXEMPT: HE WHO REALLY GATHERS THEM IS PUNISHED: WHILST HE WHO PRODUCES AN ILLUSION IS EXEMPT.
Sanhedrin 67b further clarifies:
Abaye said: The laws of sorcerers are like those of the Sabbath: certain actions are punished by stoning, some are exempt from punishment, yet forbidden, whilst others are entirely permitted. Thus: if one actually performs magic, he is stoned; if he merely creates an illusion, he is exempt, yet it is forbidden; whilst what is entirely permitted? — Such as was performed by R. Hanina and R. Oshaia, who spent every Sabbath eve in studying the Laws of Creation, by means of which they created a third-grown calf and ate it.
Footnote: It thus all depends as to whose help is invoked in performing the miraculous.
'Throughout the Talmud it is implied that impermissible 'real' magic is magic that employs demons (shedim) to create real effects' (Philip S. Alexander).
Technology, which produces actual magic-like results but whose wonders are not the magic of sorcery (kishuf), would obviously not be considered capitally punishable by Talmudic law.
For Further Study: Simcha Fishbane, 'Most Women Engage in Sorcery': An Analysis of Sorceresses in the Babylonian Talmud,' Jewish History, Vol. 7, Num. 1 (Spring, 1993): [email protected]; see also in Related on this page, 'Did the prophets practice magic?'