The marriage of special relativity and quantum concepts leads to Relativistic Quantum Mechanics. This theory can be applied to massive particles travelling at up to the speed of light and, unsurprisingly, has been sucessfully applied in particle accelerator physics.
However, as you know Steve, when it comes to a marriage of general relativity and quantum concepts, we've yet to come up with a convincing theory.
Candidates for a theory of quantum gravity include loop quantum gravity and string theory, but they pose big problems for me in that these theories are hard to explain in detail without resorting to the language of mathematics.
For interested parties, there is an attempt to explain these theories in a non-mathematical way over on the Einstein Online site:
https://www.einstein-online.info/en/category/elementary/relativity-and-the-quantum-elementary/
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Better to stick with W. Somerset Maugham, no?Like I said, I don't understand the physics very well.
Lee Smolin is talking about the search for a theory of Quantum Gravity. Standard Model can't do it. String Theory seems a bit too weird with 9 or 25 dimensions of Space. All a problem.
It is known that Black Holes have an Entropy proportional to their surface area, and a temperature that drops as you add matter or energy and make them bigger.
He said he has understood what it was that Einstein did in his successful theories. He made General Relativity "Background Independent".
And I didn't understand the next bit, but he says quantum Theory is Background Dependent. A bit like the discredited "Aether" theory. Must finish the book, but my little brain is feeling a bit fried by all these new concepts right now. I followed a Stanford course on String Theory and also General Relativity, so some of it is at least a bit familiar.
Regge Trajectories and Ricci flatness. But I think I am currently well out of my depth. This stuff takes years to get a grip on. Yikes!
Naturally, we return to the expanding universe a lot, and the section dedicated to it under Cosmology in Einstein Online is worth a look.
However, the artists appear to have got the colours of the galaxies in the animation all wrong!
According to the text:
Our galaxy (in the centre) should be red, the galaxy to its left should be green and the galaxy to its right should be blue.
Jings, as if the concept of universal expansion weren't tricky enough!
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So, dark energy may be something called "quintessence" - "a dynamic field that changes over time"?
In classical and medieval philosophy, "quintessence" is a fifth substance in addition to the four elements (Air, Fire, Water & Earth), thought to compose the heavenly bodies and to be hidden in all things.
I wouldn't get too excited about the imminent contraction of the universe though, as explained in this quote from the article:
That quote should say that, for now, the predictions can only remain hypotheses.
P.S. Look what you've done Bonsai - I just knew you'd get TNT excited!
In classical and medieval philosophy, "quintessence" is a fifth substance in addition to the four elements (Air, Fire, Water & Earth), thought to compose the heavenly bodies and to be hidden in all things.
I wouldn't get too excited about the imminent contraction of the universe though, as explained in this quote from the article:
That quote should say that, for now, the predictions can only remain hypotheses.
P.S. Look what you've done Bonsai - I just knew you'd get TNT excited!
I have not looked at the paper and would probably not understand the maths. However, you often hear about how finely tuned the universe is. Just a few millionths less dark energy and the whole thing would be collapsing or a few millionths more and it would be flying apart explosively. This immediately raises a flag to my mind. Would the cosmos really be tuned so finely out of pure luck, or is there some underlying mechanism responsible for this precarious and precise balance?
My hypothesis is that the universe is expanding because entropy is creating time which we then perceive as distance since there is an equivalence between space and time, or to use Einstein’s words is ‘space time’. My guess is the universe will continue to expand as long as entropy increases.
When you look at a galaxy that is 10 billion LY away, it is red shifted, and what you are really seeing is the time created between it and your current position (ie now) due to 10 billion yrs of intervening entropy. So, dark energy is the manifestation of entropy ie time. This will of course lead to a deeper question which is, what exactly is entropy and why do we go from order (the primordial hot plasma early universe) to the one we see today - much cooler and more disordered.
My hypothesis is that the universe is expanding because entropy is creating time which we then perceive as distance since there is an equivalence between space and time, or to use Einstein’s words is ‘space time’. My guess is the universe will continue to expand as long as entropy increases.
When you look at a galaxy that is 10 billion LY away, it is red shifted, and what you are really seeing is the time created between it and your current position (ie now) due to 10 billion yrs of intervening entropy. So, dark energy is the manifestation of entropy ie time. This will of course lead to a deeper question which is, what exactly is entropy and why do we go from order (the primordial hot plasma early universe) to the one we see today - much cooler and more disordered.
Entropy is hard. If we envision a completely ordered 2-D entity just for this discussion, imagine a checkerboard with white and black squares but the number of them is 1 million. Now order them so that it has the style of a chess board. Is this the highest level of order? I'd say so. Now, take out 50 % of the small squares and let the rest sit in their original position. The onnes taken out, toss them in a bag and shake them around, take them out and randomly poor them out so that all empty positions are filled again. Now as a 3rd step, take all of them out and shake the bag again and poor them all out on the board.
The 2nd state I would think must be the least ordered state as the 3rd, it becomes a grey even surface - very ordered...
So I take that the universe goes from super ordered - the ping-pong ball, bara-boom (order decrease starts) and then the point of expansion halt (and reverse - this is the least ordered state of the universe) and then the big-crunch (back to super ordered) - rinse and repeat. Or is it the other way - at the expansion reverse, it's the most ordered - cant figure it out
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The 2nd state I would think must be the least ordered state as the 3rd, it becomes a grey even surface - very ordered...
So I take that the universe goes from super ordered - the ping-pong ball, bara-boom (order decrease starts) and then the point of expansion halt (and reverse - this is the least ordered state of the universe) and then the big-crunch (back to super ordered) - rinse and repeat. Or is it the other way - at the expansion reverse, it's the most ordered - cant figure it out
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