The results from a slew of experiments are in: Dark matter remains elusive

The results from a slew of experiments are in: Dark matter remains elusive

Patience is a virtue in the hunt for dark matter. Experiment after experiment has come up empty in the search — and the newest crop is no exception.

Astronomical observations hint at the presence of an unknown kind of matter sprinkled throughout the cosmos. Several experiments are focused on the search for one likely dark matter candidate: weakly interacting massive particles, or WIMPs. But those particles are yet to be spotted.

New results, posted online at arXiv.org in recent months, continue the trend. The PandaX-II experiment, based in China, found no hint of the particles, scientists reported August 23. The XENON1T experiment in Italy also came up WIMPless according to a May 18 paper.  Scientists with the DEAP-3600 experiment in Sudbury, Canada, reported their first results on July 25. Signs of dark matter? Nada. And the SuperCDMS experiment in the Soudan mine in Minnesota likewise found no WIMP hints, scientists reported August 29.

Another experiment, PICO-60, also located in Sudbury, reported its contribution to the smorgasbord of negative results June 23 in Physical Review Letters.

Scientists haven’t given up hope. Researchers are building ever-larger detectors, retooling their experiments and expanding the search beyond WIMPs, in hopes of glimpsing a dark matter particle.

From Smolin's The Trouble With Physics:

"There is always more mass needed to explain the observed motion of the stars than is seen by directly counting up all the stars, gas, and dust.
There are only two explanations for this. Either the second method fails because there is much more mass in a galaxy than is visible, or Newton's laws fail to correctly predict the motions of stars in the gravitational field of their galaxy..The dark-matter hypothesis is preferred mostly because the only other possibility - that we are wrong about Newton's laws, and by extension general relativity - is too scary to contemplate."

=-=-=

"The expansion of the universe, set in motion by the Big Bang some 13.7 billion years ago, appears to be accelerating, whereas, given the observed matter plus the calculated amount of dark matter, it should be doing the opposite - decelerating.

Again....two possible explanations. General relativity could simply be wrong. It has been verified precisely only within our solar system and nearby systems in our own galaxy. Perhaps when one gets to a scale comparable to the size of the whole universe, general relativity is simply no longer applicable.

Or there is a new form of matter - or energy...that becomes relevant on these very large scales: That is, this new form of energy affects only the expansion of the universe...."

From Smolin's The Trouble With Physics:

"There is always more mass needed to explain the observed motion of the stars than is seen by directly counting up all the stars, gas, and dust.
There are only two explanations for this. Either the second method fails because there is much more mass in a galaxy than is visible, or Newton's laws fail to correctly predict the motions of stars in the gravitational field of their galaxy..The dark-matter hypothesis is preferred mostly because the only other possibility - that we are wrong about Newton's laws, and by extension general relativity - is too scary to contemplate."

=-=-=

"The expansion of the universe, set in motion by the Big Bang some 13.7 billion years ago, appears to be accelerating, whereas, given the observed matter plus the calculated amount of dark matter, it should be doing the opposite - decelerating.

Again....two possible explanations. General relativity could simply be wrong. It has been verified precisely only within our solar system and nearby systems in our own galaxy. Perhaps when one gets to a scale comparable to the size of the whole universe, general relativity is simply no longer applicable.

Or there is a new form of matter - or energy...that becomes relevant on these very large scales: That is, this new form of energy affects only the expansion of the universe...."

You've just reminded me that I have been wanting to read that book since it came out, which is almost 10 years,I fear 

So I went on Amazon and bought it. Kindle version, eight bucks. Perfect.
Thanks for the memento   Time to read it.