Why not two or four spatial dimensions? One researcher, James Scargill, argues that we could possibly have made do with two dimensions.
Physics
A symmetry the universe “must never violate”?
Sounds like a designed system all right. Too bad that’s a problem for many physicists.
At New Scientist: There’s a basic fact about the universe that we “still don’t understand”
Here’s a question: What if the basic fact we “still don’t understand” is that the evidence shows that the universe is fine-tuned and that therefore, fine-tuning is not an illusion that needs explaining away? Would that simplify things? If so, how? Another question (now that we’re here anyway): How much publicly funded cosmology exists simply to promote a naturalist atheist (no fine-tuning) worldview? And what is the science rationale for that?
Rob Sheldon on why string theory’s inflationary cosmos is a degenerate research program
Sheldon: The inflationary proposal has always been ad hoc. That is, a huge, faster-than-light expansion of the universe was proposed as a solution to the “flatness” problem, where the universe expands at a rate just sufficient to counter the gravitational attraction, where “just sufficient” means one part in 10^60 power. The inflationary model was invented to solve this fine-tuning problem.
Has a way been found to test string theory? Rob Sheldon responds
Sheldon: “This article explains precisely why thousands of theoretical physicists have not made any progress in 40 years. One hopelessly ad hoc and unsupported theory (inflation) conflicts with another hopelessly unphysical theory (string theory) and then others purport to resolve the difficulty by resorting to highly questionable phenomena (gravity waves).
Sabine Hossenfelder: Are dark matter and dark energy scientific?
Hossenfelder: “So, what’s the scientist to do when they are faced with such a discrepancy between theory and observation? They look for new regularities in the observation and try to find a simple way to explain them.” Okay but the question of whether the terms “dark matter” and “dark energy” correspond to anything that actually exists could be a different one.
Are we living in a vast bubble? Rob Sheldon explains
So now a French cosmologist is supporting the Oxford cosmologist Subir Sarkar in refuting the US-dominated 2011 Nobel prize consensus.
Rob Sheldon on dark energy: Does it exist?
Sheldon, our physics color commentator, writes to say, “I’ve mentioned before that Subir Sarkar at Oxford has questioned the existence of “dark energy” and by implication, the award of the 2011 Nobel prize. Sabine Hossenfelder’s blog links to a 7 minute summary of the Nobel prize and Sarkar’s work: But even more compelling is her Read More…
How did “wanting” things evolve?
We take the fact that life forms seek things for granted. We don’t ask why. Agency (“wanting” or “deciding” things) is as hard a problem in physics as consciousness.
A new piece of information in the question of why matter exists at all in the universe
Researchers: ” …the neutron has a significantly smaller EDM (electrical dipole moment) than predicted by various theories about why matter remains in the universe” The new find doesn’t answer the question but it enables theories to be winnowed.
Mysterious link between physics and math?
Involving quantum mechanics: In an enormously complicated 165-page paper, computer scientist Zhengfeng Ji and colleagues present a result that penetrates to the heart of deep questions about math, computing and their connection to reality. It’s about a procedure for verifying the solutions to very complex mathematical propositions, even some that are believed to be impossible Read More…
The remarkable connection between mathematics and physics
According to Mullings, the reason for the association between mathematics and physics is not that the mathematics is causative but rather that mathematics studies the logical structure of possibility and constraint. As a result, if the mathematics successfully captures the possibilities and constraints in the real world, it will provide a tool for further analysis of potential possibilities.
Sabine Hossenfelder asks: Does nature have a minimal length? Could it point to a final theory?
Hossenfelder: What does this all mean? Well, it means that we might be close to finding a final theory, one that describes nature at its most fundamental level and there is nothing more beyond that. That is possible, but. Remember that the arguments for the existence of a minimal length rest on extrapolating 16 orders magnitude below the distances what we have tested so far. That’s a lot. That extrapolation might just be wrong.
Let us now praise normal science: Chad Orzel responds to Sabine Hossenfelder
As Chad Orzel explains, he considers Sabine Hossenfelder’s dismissal of much current physics “a little too sweeping.” A lot happened in the dull years.
Rob Sheldon unpacks the new “backwards causation”quantum mechanics research
QM is all about microstates and their measurement, but not about macroscopic properties that you and I normally associate with everyday objects–smoothness, ripeness, tools like “hammer and nail” or biology like “chicken and egg”. So indeed we can entangle QM microstates, but can’t entangle chickens and eggs, and therefore using those terms creates a semantic muddle.