In this post I will deliver a step-by-step description of the general theory.
When Einstein formulated his theories about the universe he said it was intuitive work. Living in a time and place where enlightenment wasn't well formulated he took the concept of now and formulated it into the language of science based on his intutition.
In general relativity, Einstein says that time and space are connected and exist as what is called space-time. As you read this text you will notice that you do so at a specific time in a specific place. You cannot remove the place or the time, they are tied together. Every time you experience something you are in a place, and every place you have been to was at a time. This is space-time.
From space time Einstein started to draw natural conclusions. One realization he made was that if space and time are connected, everything that has an effect on space has to have an effect on time. He described gravity as geometry of space time, and the consequence is that gravity also has an effect on time. Light has shorter wavelengths near heavy objects, and longer wavelengths near lighter objects.
Another consequence is that speed effects space. Normally we think of speed as something that concerns time and speed. But space and time are connected, so velocity also has an effect on space. Objects traveling at high speed experience a different space compared to objects traveling at lower speed. A man who had been on a long journey in space traveling at high speed comes back to earth barely older than when he left.
So far so good, space time exists. However, here is where we have to back to the original concept and once again examine this concept of space time.
Space time is the concept that space and time are connected. What this means is that you can not go back in time without also going back in space. You can not go forward in time without going forward in space. In other words, and this is crucial, there is only now. I repeat, as you read this text you do so at a present time in a present space. They are connected and can not be separated. This "moment" is the only space time "moment".
If you have to read the last paragraph again please do so, because from this point on I will cover the natural intuitive response to Einsteins theory.
There is only space time. Einstein knew this, but he missed out one crucial piece of the puddle.
There is a difference between cultures on how we imagine our lives through space time. In western culture we walk into the future, with our backs to the past. This was the way Einstein saw reality. However, a more intuitive answer is given in some cultures and that is we move with our backs to the future and see only the past. This is important!
In the current version of space time, we view ourselves as seeing the past and being in the present while at the same time were are walking with our eyes towards the future! This is intuitively wrong. Einstein didn't see that space time exists not only in the past and present but it is also the future.
How can we verify this to ourselves? Imagine a coin toss. From our perspective we know the past (heads or tails) and the present (probability of landing heads or tails) but we cannot say anything about the future. This is not intuitive because space time exists also in the future, as soon as the coin lands we know if it is heads or tails. Now imagine walking with your eyes into the future, what would this look like. It would mean that we know the future (how it landed) and the present (probability of landing heads or tails) but we couldn't say anything of the past (heads or tails). Now do the thought experiment of walking with your back into the future and witnessing an event that happens from the future. Intuitively this would be very confusing because it would only exist as a probability until the future arrives at which point it would be heads or tails. This is what we see in the so called schroedinger equation, where until the future arrives we cannot know if the coin is head or tails. Of course, this is simply an observer in positive space time (present and past) witnessing an event in negative space time (present and future).
I know this seems counter intuitive at first but if you accept that space time is real, then it is the intuitive conclusion that space time exists both in past, preset and future.
This has a number of verifiable conclusions. When the universe was born, from our perspective there was no future yet and so there should be no negative mass at that point. Negative time means there should be negative mass that is distributed in a way that we can predict.
Finally, this means that all is everything there is and nothing. In the manner of Watson and Crick, I don't have to exaggerate the importance and impact of what I have written here.