Ray Kurzweil predictions of a human level general AI by 2029 and the singularity by 2045 (https://en.wikipedia.org/wiki/Ray_Kurzweil#Future_predictions) might be wrong, because he bases his predictions on the enduring validity of Moore's Law.

Moore's Law (which says that components on a integrated circuit double every two years and, hence, also its speed) is facing challenges.

Currently, the rate of speed increase is more 2.5 or 3 years than 2 and it's not clear if even this is sustainable.

As the nods on chips keep shrinking, quantum mechanics steps in and electrons start becoming hard to control (https://en.wikipedia.org/wiki/Moore's_law).