Let's say someone attaches a timer to a fuse / lighter that sends a spark to light the candles. Can lighting be done automatically, or must each candle be lit by human physical action, only?
As @Yehuda asked an interesting question if the person must be present, there is an opinion that one may say the bracha upon seeing the candles lit, even if hwe has not lit it himself (See Talmud Shabbat 23a). So, assume that the timer caused the candles to be lit, and while they were still lit, the home owner came into the room and saw the candles. Can he make the bracha and fulfill his obligation?