What was the Philadelphia Experiment?

Philadelphia Experiment not a hoax?

• My grandfather claimed he was aboard the Eldridge, his wife showed me before and after photos revolving around his time on the ship. From her account, many of his crew died, vanished, suffered mental illness or somehow became embedded with the ship. Does anyone else HONESTLY know survivors of the experiment? His left arm was amputated and he suffered dementia until his death in 1994. I've researched it online and am stunned by the results and his wife has had cataracts and has trouble reading so I'm sure she didn't fathom the story when it came to light. And aside from that he kept a journal which could hold monetary value if valid but I convinced my brother not to sell it. What's odd is that she mentioned it when I told her I wished to time travel (I believe time is the measurement of light on various accounts). And sarcasm isn't a native tongue in our family, so I'm afraid of the truth but in earnest would like to know more from factual familiars.

• Answer:

  There were lots od 'degaussing" experiments conducted on the Eldridge during WW II. No time travel, no invisibility and no casualties. It is very easy to look up.