Current physics theory postulates four possible forms of alternate universes. This is my interpretation of the theories:
An infinite number of sub-universes exist inside one giant multiverse (multiple universe). The only reason we have not seen the others is because they are so far away that the light has not had time to reach us, yet. All of the universes duplicate each other, and what happens in one universe happens in all of the universes of the multiverse.
An infinite number of sub-universes exist within a giant multiverse, called the block, and these sub-universes are like soap bubbles floating at random through the air. There is no similarity among the sub-universes. All possible combinations of things exist in one sub-universe or another. Humans exist in one of the sub-universes, but might not exist in any of the others, or some sub-universes might contain humans and others might not. A new universe is created every time two of the sub-universe "soap bubbles" touch each other, but the old sub-universes are not destroyed in the process. Thus, the number of sub-universes continues to grow, but the block holding the sub-universes is infinite in size, so it will never be filled.
An infinite number of sub-universes exist within a giant multiverse, called the block, and these sub-universes are like parallel planes. They never interact in the physical sense. A new universe is created every time there is a choice offered. The old sub-universe continues to exist with one phase of the choice and a new sub-universe is created to accommodate the other possibility. As an example, suppose someone drops a coin onto a flat surface from a sufficient distance so that the coin lands on edge. In one sub-universe, the coin comes to rest on edge and never falls over. Two other sub-universes are created, one in which the coin falls heads up, and another in which the coin falls tails up. This is going on all of the time, so every time you decide whether or not to eat that next cookie, a new sub-universe is created. The possibilities here are mind boggling.
The type 4 universe is harder to describe. There is an infinite number of sub-universes in the block, all existing at the same time and occupying almost the same space. They are separated by one or more of the seven dimensions that we cannot detect. The Type 4 multiverse has 11 dimensions: the X, Y, and Z, plus time directions that we perceive, and seven more which describe the way the sub-universes can exist all at the same time. There is a series of experiments going on trying to detect one of these other dimensions, concentrating on a particle called the graviton, the smallest unit of gravity.
The above is not fiction! It is the simplest explanation for the mathematical equations which describe space and time. One day, humans may know which of the four is the correct form of the solution. Of course, there may be a fifth form which nobody has thought of, yet.
This story takes place in a Type 2 universe.
Mu7437alpha, called Mu7a by his friends, was diligently working in his laboratory on his machine for his doctoral thesis. This machine was intended to allow communication among the possible multiple universes that physicists had long postulated, but had never been able to prove. Mu7a was sure that he had the key to this communication.
Mu7a was sure that modulated laser beams striking an iridium mirror in the right sequence would transfer the mirror into a viewing port, and might even allow energy besides light to pass from one sub-universe to another. Anyway, his thesis and future career were hanging on getting this just right. If he could make it work, he would be assured of a life-long stipend from the government which would allow him and his family to live in luxury. All he had to do was to give a few lectures a year explaining how his machine worked. Mu7a was determined to make the machine work or die of exhaustion from trying.
He already had the math worked out, it was just a matter of getting that last damned laser modulation system to stabilize. Mu7a had been working on it for over a month, but there was still a slight drift in the modulation frequency that he was having one hell of a time getting under control. He was sure that it was fluctuating temperature in the tertiary oscillator that was causing the problem. In desperation, he had constructed a liquid nitrogen tank system to warm up the oscillator to just above room temperature. The boiling nitrogen should provide a stable enough temperature at least to prove that the machine would work.
Just as Mu7a was about to run another test, his communicator flashed a purple light indicating that he had an incoming call. In disgust, Mu7a turned to his communicator and signaled, "Go ahead, but please hurry." The combination of flashing lights told him that the caller was Mu7437beta, one of his co-husbands to their wife, Mu7437omega.
Mu7b said, "OK, I'll keep it short. Mu7o told me to call you to remind you that you must be home tonight before 9:00 PM. Mu7o says that she will be fertile tonight, and you had better be here if you want your genes represented in the new child. Otherwise, the other five of us husbands will proceed to impregnate her without you."
"Oh, shit! Yeah, I don't want to miss that. Tell her that I have just one more test to run before I shut down for the night. I'll come straight home from the lab, so I won't be late."
"OK, I'll tell her. Just don't be late!"
Mu7a broke the connection and turned back to his machine. Ah, good! It looked like the temperature of that pesky oscillator had stabilized, so he was ready for the test. He was in a hurry, because Mu7a didn't want to miss the upcoming sex orgy his wife was planning. He had been aiming for a sub-universe that his math calculations told him should be reachable with these settings. Mu7a turned on the bank of lasers and waited for a scene to appear in his iridium mirror.
It worked! He seemed to be looking at a strange device suspended from a tower. He couldn't tell anything about it because of the small size of the viewing screen. Just as he squinted at the screen, there was a white flash, and the object disappeared. The object filled the screen, so when it exploded, a beam of energy came through much like a laser, except that it was mostly plasma. There was some radiation from alpha particles to X-rays, but most of the destruction was done by the plasma beam.
Fortunately for Mu7a, he was not in a direct line with the beam of plasma, but the secondary destruction did send him to the hospital for six weeks. Later, he was able to salvage most of his machine, but he was over a year rebuilding it to the point of functionality.
Of course, it was years later, our time, that I learned of this accident the first time Mu7a made contact with our universe. I got into communication with Mu7a quite by accident and coincidence. I was a chemistry major at Auburn University, a senior, but my hobby was astronomy. I had built several of my own refracting telescopes, up to a 7-incher, but I was now working on a 12-inch reflector. I had an apartment on the outskirts of town, and my landlord allowed me to work on my hobby in an unused section of his garage. I was an orphan, so I had no place to go during the off-days around Christmas, etc., so I spent a lot of time working on my telescope.
I was far enough out of town that I could view the sky with very little problem with light pollution. One night, I was working on getting my latest telescope set up when I noticed a strange light in the sky. It seemed to be a square of red light about 150 feet off the ground. This was impossible! There was absolutely nothing in the vicinity that would look like that, and it could not be an artifact from an airplane, not that close to the ground.
I knew that it had to be close to the ground, since I could see that it was square. At a distance, no matter what its true shape, a bright object at night is going to look somewhat round. Yeah, I know, but the moon is already round.
Anyway, I ran into the shop and grabbed a 3-power telescope I kept around for looking at close up objects. Well, I could see Jenny Holmes bedroom window from my shop window, and I needed something convenient to see if it was worth getting out one of my more powerful scopes.
I used the small telescope to look at the bright red square, and wasn't sure what I was seeing, except that it obviously was not some big scientific or government project. If it was any one of those, why was it looking at me in the backyard at night? I do read a lot of science fiction, so I thought I would have some fun and pretend that it was an alien communication device.
I kept a very powerful LED flashlight with me to do the original setup with my telescopes, so I took it out of my pocket and flashed a series of blinks at the red whatever-it-was. The first series was the low primes: 3, 5, 7, 11, 13. At this point, my hand got tired, so I quit. A few seconds later, the red object seemed to change color. It took me about 30 seconds to see the color shift from red to yellow, then I saw a flash sequence of 13, 11, 7, 5, 3. When I recognized what I was looking at, I flashed back 17. A few seconds later, an answer came back: 19.
I next flashed the sequence 1, 1, 2, 3, 5, 8. A few seconds later, 13 was flashed, which is the next number in the Fibonacci sequence. We spent about an hour flashing other sequences back and forth at each other until my hand gave out for real. This flashlight was not built for flashing like this, so there was a lot of wear and tear on me. If this sort of thing kept up, I was going to need a different flashlight.
I didn't know how to say goodbye to my new friend, so I turned the flashlight on and just waved it at the little square of light before I just turned it off and left it off.
I had a lot to think about. This was just like the first communication efforts I read about in many science fiction stories. The problem was, I still didn't know if the guy behind the red square was a joker playing a practical joke on me, or if it was a legitimate communication effort by an alien. One thing for sure, I wasn't going to say anything about it to anyone else until I had a lot more information. Hell, if this really was an alien trying to communicate, as soon as I opened my mouth about it, I would probably wind up in Roswell or some such place and be completely frozen out of any further communication with the guy.
I decided to play it cool and see what happened tomorrow night. It was a cinch that our communication method would not work in broad daylight. I did invest in a different flashlight that was easier to use for this type of on-off communication.
My friend was back on the next night and on the following four nights. We continued to flash number sequences at each other, some of them quite complicated. I sure was glad I had gotten the new flashlight. Unfortunately, after six nights of communication, the seventh night was blank. I kept checking, and every night for eight more days was like that. I wondered if that meant that the guy at the other end of the circuit had gotten bored with me, or if he was having some sort of problem.
I promised myself to check every night for the next 10 nights, in hope that he would come back. Nothing happened for the next three nights, then he was back, and in spades! This time, he had done something to his system, because the red light was almost three feet square and very close to the ground. So close, in fact, that I could reach out and touch it.
I got real close to the red spot and examined what I could see. Laboratories were the same the world over, and maybe the galaxy over, because I could tell that I was looking at a portion of an engineering lab. As I watched, a dim figure walked, slid, glided (whatever?) over to the screen and stared back at me. Well, I'll be a monkey's uncle! The figure I was looking at was the spitting image of ET from the movie, except this one had three eyes. Well, for lack of anything better, I was going to name him "ET," at least until I learned his real name.
I noticed that the red light coming from the screen appeared to be the ambient light that ET preferred. I had no reference, so I could not say how tall he was, or anything else about his physical size. ET could be 20 feet tall or 3 inches tall and there was no way I could tell without a reference. It also dawned on me that he would have the same problem with me.
Suddenly, I had a flash of genius! I ran to my workshop and picked up a measuring tape 12 feet long. I rushed back outside, hoping that the communication circuit had not been broken. Yep, there it still was. I walked up to the display and used the tape to measure its height. By luck, it was exactly 34 inches high. I made a point of giving ET a good look at the number 34, then I laboriously went through the numbers on the tape, pointing to each one and flashing the number to him. Fortunately, by the time I got to 12, he made it clear that he understood our numbering system. It was getting hard to flash that many times without making a mistake, so I was very glad that ET was a quick learner.
I thought that I would give him an idea of my height, so I stood up straight and pulled the tape out to 71 inches. I held the tape up beside me to show him what I was measuring, then I showed him the 71 on the tape. He clapped his hands (six fingers and two thumbs on each hand), and I took that to mean that he was pleased.
By this time, I was exhausted, so I waved the light at him in a back and forth motion. I hoped that he realized that I meant "goodbye for now." Apparently he did, because he reached behind himself and did something; when he did, the red display disappeared.
ET and I needed a better and more complete way to communicate. Since it appeared that sound did not penetrate the display, only light as far as I knew, it seemed to me that writing was the obvious solution. The problem was which language to use. I am lousy with languages, so I hoped ET could learn English. If not, I would try to go with his language.
I did decide to simplify the language: no subjunctive, no irregular verbs, no cases on pronouns. I was also going to make the spelling phonetic. Homonyms were going to be enough of a problem. Well, I would solve problems as we came to them.
I went to the college book store and picked up a whiteboard and an assortment of pens. Shit! That stuff was expensive when you are living on a student's income. I also picked up some file cards and other stuff that I thought might come in handy, things like a periodic table of the elements.
That night it rained, so I couldn't do much. I showed up with an umbrella when the display showed up. I pointed to the water running off the umbrella and waved the flashlight. ET started to turn off the display, but I managed to get his attention and tried to signal for him to follow me with the display into my workshop. I am sure that he understood what I wanted, but he waved his hands back and forth, so I assumed that meant that he couldn't do it. Oh, well, it was a good idea while it lasted.
I went to my workshop and piddled around for a while. While I was in there, it dawned on me that ET might not be able to move his output on such short notice, but might be able to do it if I gave him enough time. It was still raining lightly the next night, but there was no sign of ET's device, so I hoped that meant that he was working on some way to make it mobile.
The next night, the weather was clear, and the display was in its usual place. I walked toward it, and ET apparently saw me. As I walked toward the screen, the screen moved toward me. Hooray! I guided ET into the workshop. It took some time, since the device was not good at following me around corners, but we finally made it.
I had set up the whiteboard in the workshop the day I bought it in anticipation of this happening, so it was ready when ET was. I started off with the symbols for numbers, since we had already established them from the tape measure demonstration. I wrote the number on the whiteboard and flashed the flashlight the proper number of times. By the time I got up to 12, ET had the idea.
Now, things got interesting. I pointed to myself very emphatically and printed Derek on the whiteboard. After about a minute, ET seemed to get the idea. I then printed the symbols for my new English alphabet. I skipped "c" because I planned to use "k" for the hard "c" and "s" for the soft "c." I had decided to use the "c" symbol to replace the "th" diphthong, and "f" would be used for "ph." Therefore, for ET's benefit, "the" would be spelled "ce."
I spent only a few minutes with the new alphabet, since all I wanted was to show ET what we would be working with. I moved to math equations of the simple form of 1 + 1 = 2. I wanted to use the "=" sign as a symbol for "is" when I got to something abstract like "Derek is a man." I would start out with "Derek = man." I thought ET's obvious math expertise would help him grasp the idea of the verb "is."
After a few minutes of this language exercise, ET stopped me for a moment while he left. He was back in seconds with something I was sure had to be a camera. He was taking notes by photographing my whiteboard!
After about 90 minutes, both of us were getting very tired, so we quit for the night. We would pick up the class tomorrow night.