Nikola Tesla is credited with far out, “can you do this, can you do that” type of thinking. He enjoyed the mental challenge. So, for example, Tesla’s preliminary thinking would be, (a) Can you make an object invisible?, then (b) Can you get free power from nowhere? Tesla was quite successful at “b”, to the chagrin of some people who later buried this aspect of his work. Tesla’s insatiable curiosity led him to the invisibility question. FDR saw how this could have a military use and used his navy connections to obtain backing for an actual invisibility project. (Background: Our Friend, The Ether (Part 26), Ersjdamoo’s Blog entry of November 27, 2013.)
By the start of World War II and the German U-boat blockade of Britain, there was a strong pressure to find a better way to get supply ships past the blockade. An invisible fleet of supply ships might confound the German blockade. Therefore there began to be an increasing impetus to make the invisibility project successful.
A successful test on a small navy ship, a tender, occurred in September 1940. In the Brooklyn Navy Yard this ship became totally invisible. There was a big push as well for radar invisibility. The project at this point was given a name, “Project Rainbow.” This topmost priority project next sought to produce invisibility on a much larger ship than a tender. By late 1940, President Franklin D. Roosevelt (FDR) had given the project the needed large ship which was sent to the Philadelphia Navy Yard.
The first ship which they had made invisible was a small ship of about 350 tons, the aforementioned tender. No one had been onboard this small ship at the time of the test. The worry was, if we make this ship invisible, will it ever come back? The power supplied was external, with cables going out to the tender. The later destroyer escort class of ships used in the ongoing experiments typically ran around 1600 tons. An even larger ship, a battleship of about 30,000 tons, was tried but there were too many problems.
No one had been onboard the small navy tender at the time of the September 1940 test. But personnel would have to be onboard for some of the later tests. What use would an invisible ship be without sailors?
Nikola Tesla left RCA and after 1939 was free to spend a lot of time working on Project Rainbow. Al Bielek had joined the Navy in 1939, after his work on a Ph.D. in physics. In 1940, Al’s brother Duncan Bielek also joined the “invisibilty project” team. In January 1941 the Navy moved Al Bielek and his brother out to sea on the USS Pennsylvania. In October 1941, Bielek and his brother took leave to San Francisco. On December 5th they received orders to return to Pearl Harbor. But their orders to return to the USS Pennsylvania at Pearl Harbor were suddenly cancelled just as they were boarding an airplane for the return trip. Bielek says he was told by a top-level officer from the Office of Naval Engineering, “We don’t want you to go back to Pearl Harbor. We have reason to believe the Japanese are going to attack Pearl Harbor within 48 to 72 hours. You’re too valuable to us. We don’t want you there. Stay here in San Francisco and in January you’ll be returned to the project at the Institute of Advanced Study.”
(On December 7, 1941, when the Japanese raiders arrived over Pearl Harbor, the battleship Pennsylvania was in the Pearl Harbor Navy Yard’s large drydock and therefore was beyond the reach of the torpedoes that inflicted such devastation on four of the fleet’s other heavy ships. Though bombers of the second wave attacked her, the USS Pennsylvania was directly hit only once, by a bomb that struck amidships, putting some of her five-inch guns out of action but generally causing only minor damage to the heavily-constructed ship. )
So Al Bielek and his brother Duncan returned to Project Rainbow in January 1942.
In the beginning of 1940 through the summer, Al Beliek went through orientation under John von Neumann. There he was introduced to theories not taught in the textbooks. This physics was far ahead of what was in the books and of what was considered “normal physics theory.” In this “secret physics” they were dealing with things like multiple realities, time fields, and all of the related math including that of quantum physics. Besides this, Albert Einstein had already completed his unified field theory, unbeknownst to those of the “normal physics.” The completed unified field theory was highly classified but was available to those working on Project Rainbow. Also available to the team were Dr. Levinson’s (MIT) time equations dealing with the “time matrix”. Through this orientation, Bielek was soon brought up to speed but it took longer for him to truly comprehend what he was involved in. Bielek and his brother Duncan were being groomed for something in the future which they did not yet know about. Eventually, someone onboard a ship was going to have to run further experiments. The Project Rainbow team did not want just any sailor to be running onboard tests. Even an officer who did not understand the theory would not do. Al Bielek and his brother Duncan were being trained to handle the task. Someone not knowing what they were doing might cause the ship to drop out of time altogether. An “artificial time zone” in a sense was being created. A “phase shift” where the ship would rotate partially out of the normal time field until all the electro-magnetic energy from outside (light and radar) would wrap itself around the ship was desired. But you had to know what you were doing, so knowledgeable persons were needed onboard to run the experiment. 
——- Sources ——-
 “Pearl Harbor Raid, 7 December 1941: USS Pennsylvania, Cassin and Downes during the Pearl Harbor Attack”. http://www.history.navy.mil/photos/events/wwii-pac/pearlhbr/ph-pcd.htm
 For info on my source for Al Bielek’s information, see “Our Friend, The Ether (Part 26)”, Ersjdamoo’s Blog entry of November 27, 2013. https://ersjdamoo.wordpress.com/2013/11/27/our-friend-the-ether-part-26/