Please let me know why the gold and silk are haram for men in Islam. (please help me with all the scientific and logical facts as I need to answer this to a non Muslim)

We in Islamic sciences don't go after scientific reasoning as science is in its initial stage. In my special words science is a baby of 200 to 300 years only and has to go much ahead to reach a position where they may not retract what they have proved before as many scientifically proved things were later retracted in medical field. I can quote ten things. So we need to wait for our 12th Imam (as) to come and guide us