CPC Lecture January 23 - 'Dark Energy', Dr Matt Bothwell

Around a century ago, Edwin Hubble made one of the most important discoveries in astronomical history: the Universe is expanding. Ever since Hubble, understanding exactly how fast the Universe is growing has been one of the most important tasks in cosmology. Today, astronomers are faced with a puzzle: why is the expansion of the Universe speeding up? Attempting to answer this question will force scientists to question the most fundamental assumptions in all of physics, and might take us beyond the edge of the Universe itself.

[chaos]

Interesting lecture. I think that the reason there is such a disparity between dark energy and quantum theory, (virtual particles) is because it's probably wrong. The person who asked the question about repulsive gravity I think hit the nail on the head. The problem is that we don't understand gravity as an attractive force, and therefore can't explain it as a repulsive force. This is because we don’t understand what spacetime is or how it works. There is actually quite a simple explanation rooted in quantum mechanics. The solution boils down to the universal gravitational constant not being a constant constant. It's a time based variable. G increases with time very slowly. This is what actually causes attractive gravity. But because it is increasing, any fixed mass/energy at any fixed distance has to gain gravitational potential energy (which is actually a negative quantity). But and increasing negative potential energy breaks the first law of thermodynamics and as scientists will know energy can't be created or destroyed. So increasing gravitational energy (negative) has to be balanced by a gain in positive energy, or kinetic energy. The further an object is the greater the gain in negative potential energy and therefore the greater the amount of positive kinetic energy is required to balance it. For any mass that starts out with essentially zero kinetic energy from other sources we end up with Hubbies law. For masses that also carry additional kinetic energy we end up with an accelerated repulsion. The more initial k.e. the greater the acceleration. But its not really a repulsive force, its the result of spacetime itself stretching like a three dimensional piece of rubber. The universe always ends up un perfect balance between negative gravitational energy and positive kinetic energy. Dark energy is not virtual particles. So what is going to happen to the universe? Well according to this hypothesis, gravity will get relentlessly stronger locally, while distant matter is pushed further away. Eventually, complete gravitational collapse of baryonic matter. The universe is kind of going to develop huge voids as more and more matter collapses and will eventually just fizzle out. An analogy would be blowing a soap bubble. At first it grows, until it gets so big that it can no longer remain stable then huge holes/tears start to appear and it very quickly loses its integrity and dissappears.

[michaeltrillium]

So 10^120 is the magnitude of dark energy assuming quantum mechanics empty space theory is the pushing force. Where is that nice balancing (almost) 10^-120 keeping the Universe expanding but not blowing up coming from?

[fanbutton]

Am I in the right place....is this the pseudo-science convention where people believe that 97 percent of the "universe" consist of invisible stuff?

[daviddean]

It is so bonkers now to see men brazenly sporting pipes in their photos.

[danechegoyen]

This short video on cosmology clearly links: dark energy, gravity, the curvature of space, black holes, increasing expansion of the universe, and inertia, all in one simple dynamic lower dimensional physical model of the universe whose linking features are real and understood. 

[JungleJargon]

The vacuum energy is the opposite of the expansion which is also associated with black holes that are growing in size by absorbing space time. Again, it’s the opposite of inflation.

[JungleJargon]

An infinite universe is an appeal to infinite power and ability since energy cannot make or direct itself.

[chrisoakey]

The expanding universe, as with the big bang, keep needing revision because everiwe see shows it doesn't fit. Alternately if light is allowed to slow by 4.6mm/s/year, the redshift is explained. Amd we know light slows because of refraction. We know space is not actually empty. So we know light therefore must slow as it travels. But by tiny amounts, so we only see it as the source gets a very long way away. Hense hubbles observation. The only problem is our model that doesn't work, says light cant slow in a vacuum. But again, even space isnt a pure vacuum.
Why does the model not work? Because nothing can go faster than C, but the redshift shows that "space-time" is expanding faster than C.
As a result of the change to the way we look at redshift, we dont need the absolute BS dark stuff that we cant find but otherwise the math doesn't work😂. So it must be there😂.