just want to share one graph and explain it a little

 

This is from resonaances.blogspot.com, from here: http://resonaances.blogspot.com/2016/09/weekend-plot-update-on-wimps.html

What the curvy lines, the CRESST, CDMSlite PandaX and Lux lines are the constraints from direct detection, if you google the various acronyms above you can find out more about the experiments, but mostly they are large underground tanks of various substances which should be able to detect dark matter and of course they detect neutrinos too.  You might think, well if the universe is so full of dark matter what is the problem detecting it.  The thing is we don’t live in empty space we live right next to this huge ball of gas called the sun.  There is another weakly interacting particle that comes from the sun and a few orders of magnitude more of neutrinos pass through our body every second compared to dark matter.  I did the calculation a while ago, so while there might be 100 billion or so neutrinos passing through the human body every second there are “only” a few billion dark matter particles passing through our body every second.

That gray thing in the graph called the “v floor” is the theoretical lowest limit that dark matter detectors can go.  At that point due to neutrino scattering you can’t go any lower.

 

Ok, now look at that Z portal g=1, that is the model which we have been using ever since dark matter was discovered in order to calculate from the microwave background radiation how the universe grew.   This is a log chart.   That model . . . . which we still use, because we don’t really have any simple alternative, is about 1,000,000 times higher than our current direct detection limits.  We should have found wimps a long long time ago.  But nothing has been found.

I had always figured that we could just build bigger and bigger wimp detectors here on earth but it looks like we are almost at the limit and no dark matter particles have detected at all and while I guess it can still be found in that tiny little slice it doesn’t seem likely at this point.

It seems that the only way to go forward now for dark matter detection now that we have almost reached the limit is astrophysical observations.

Go read the link above for more, it’s a short read.

So if you follow them sciency blogs and videos you will know that there’s been a big push among those who study ancient homonids to ascribe human hairlessness to persistence hunting. Barefoot running enthusiasts take this evidence and run with it in their promotion of daily long distance barefoot running. I tend to think that it’s more evidence of lack of imagination than a real theory about why we are hairless. Right now we have a few theories, for instance, the aquatic ape, hairlessness to protect against lice, and persistence hunting. We also used have to a theory that clothing could have caused hairlessness but thanks to lice studies and human genetics we know humans were naked until a few hundred thousand or so years ago but being hairless goes way further back, 1.2 or so million years ago. The reason we can figure out pretty exactly when it happened is thanks to some incredible advances in human genetics.  If you shave a chimp you will notice that he is pale under his fur.   When humans lost their fur, they also had to develop dark pigmentation to protect against UV damage from the sun.  Scientists have been able to study all the genes for skin color but of interest is MC1R.  By studying genetic drift and working backwards, scientists have been able to put the time when we lost our fur as 1.2 million years ago.   So the theory that clothing has anything to do with it us becoming hairless is out.  This has left the persistence hunter theory as front and center.  I think however, that there are just too many other things that could have happened too many other possibilities things that we haven’t really studied yet for  persistence hunting to become the default explanation.  For one persistence hunting is terribly risky.   You use up tremendous amount of calories running that much so if you have a success rate of less than 50% you are losing calories.   What is more, if you hunt in a larger group, the success rate has to be almost 100%.   There’s also the problem of running that far and then having your prey taken away by other predators.   So I’m not a huge fan of persistence running as the only or even primary reason for us becoming hairless.  I think there should be many more theories about why we lost our fur.   Not just these handful but many more possibilities.  For instance, how about fire?  We also know that fire was invented between 1 million and 2 million years ago but at the time we first captured fire we probably didn’t know how to create it just how to keep it burning if we found it from a thunderstrike.  I’m not suggesting that the fire caught early hominids fur on fire so that’s where the selective pressure is.  I presume that if a spark caught a bit of your fur on fire as an early hominid you would know enough about how to put it out.  I think it might have been more like, well suppose there was a hominid that lacked some of the hair of his fellow tribe.  He would want to keep the fire burning all the time well because it’s cold at night even in Africa.   He would keep it burning, bank it at night, bring it up again in the moring.  So maybe the rest of the tribe would not care too much,  but since there’s already a fire going then they would cook their food with it.  There have been recent studies which show that the caloric values of cooked vs raw foods is incorrect.  Raw foods give you about half the amount of calories as cooked foods, so cooking foods would give the tribe with a fire keeper a significant evolutionary advantage.   I’m not saying this is the right theory, but I just think that the persistence hunting theory has really gained too much ground recently and there need to be more theories, more ideas.   The reason more theories help us is that a new theory will give scientists who study hominids new ideas to test and perhaps show a path back to why humans became hairless 1.2 million years ago.

so I was in Cincinatti last month. Cincinnati the city named after Lucius Quinctius Cincinnatus. And so I learned a bit more about him after looking at his statue there along the Ohio river.

First of all, anyone who tells you that George Washington based his life on the bible, nope. How about George Washington basing his life after the western ideals of the enlightenment, like Hume. Nope. George Washington looked back towards Ancient Rome. No, not the Rome you see in the movies. Not Julius Caesar. George Washington would have helped Brutus guide the dagger in and good riddance to a dictator. No, George Washington (along with many other founding fathers) based his morals and convictions on the ancient Roman Republic and in particular on the life of Cincinnatus. In 458 BC the tribe of Italians called the Aequi threatened to destroy the nascent roman republic. Rome was in desperate danger with the army besieged. The senators fell into a panic and authorized a dictator and nominated Cincinattus giving him absolute power for a period of six months. The senators went to Cincinattus finding him ploughing his field. Cincinattus marched to relieve the army and saved Rome. Fifteen days afterwards he disbanded the army and returned to the plow. This is the hero George Washington looked up to. I have heard that one reason George Washington decided to continue leading the continental army despite calls for his resignation after he lost New York city to the British and the terrible crisis of the army in 1776 is if Washington resigned from his post he would never be able to lay down his arms like Cincinattus. So it was in 1783 when the new born USA achieved independence that George Washington resigned from his post as commander-in-chief despite calls for him to remain in charge for the rest of his life.

To be honest I’m not sure if that’s how I think a government should run. You know on the honor of men. On their principles. Because no matter what you can’t always have a good man in charge. So yes, it was nice that George Washington led by example and followed the ideals of Cincinattus but I think you need more than that you need to codify this sort of ideal put it into laws and force the leaders to obey them. After all, even though George Washington could have remained president for life he gave up his post there after 2 terms, and it wasn’t until FDR abused his position by winning elections for 4 consecutive terms that congress passed the 22nd amendment limited the elected president to two terms. I think that’s how you want to do it.  Codify it and force the leaders to obey the law, not just rely on their honor.  George Washington, Cincinattus, they both led by example, showing what can happen if you give absolute power to someone who willingly gives it up when the job is done. You have to admire that but also recognize how rare to have this sort of leader.

The amount of energy you receive from the earth is the projected area times the solar constant times 1-albedo, or pi r^2 * K * (1-albedo), the amount you emit is going to be proportional to this boltzman equation times the surface area of the earth, or 4 pi r^2.  The earth in other words receives the projected area in solar radiation, which makes sense and radiates it out from the entire earth a sphere.   If you set the E(emitted) = E(absorbed) notice that the pi r^2 factors cancel out and you are just left with the factor of four.  The boltzman equation just means that the temperature is proportional to the temperature of the object to the 4th power.  Scientists knew about this back in the 1800’s, and in fact did this same calculation I’m doing now.  so let’s set up the equation, albedo is .31, solar constant at the earth’s radius is 1361 watts per meter squared and the stefan-boltzman constant is 5.67e-8 watts/m^2K^4

K  * (1-albedo) * pi r^2 = boltzman constant * T^4 * 4 pi r^2

1361 * .69 = 4 * 5.67e-8 T^4

T = 254K or -3F

Without greenhouse gases the earth would be -3F.  This is a very simple calculation and something we have known for hundreds of years.

The end of physics has been proclaimed several times.  For instance at the end of the 19th century when statistics and mechanics were figured out, some thought it was going to be merely a matter of calculation.  Between Newton and Maxwell they might have figured it all out right?  Except there were very simple problems that defied calculation.  For instance the “lumineferous ether” didn’t seem to exist and the “ultraviolet catastrophe” led to first relativity and secondly to quantum physics both of which Albert Einstein had a hand in.  After general relativity was fleshed out it took from early in the 1900’s up to somewhere around 1965 to finally figure out quantum field theory and what we now call the standard model.

 

But it’s worth looking back at right around 1960-1965.  Just like for Einstein back in the early 1900’s there were enough clues that anyone who looked long and hard enough at the problem would be able to eventually figure it out.  We had something called the “particle zoo” for instance Muons (which are basically heavy electrons) all kinds of mesons (quark + anti-quark, pions, rhos, phi omega).  This zoo of 40 or so “elementary” particles gave rise to all sorts of wild theories, various incarnations of the s-matrix and yes, string theory was invented to try to explain it, but eventually we found out that the strong force worked the same as the electro-weak force, that is the same equations held “all” that changed were the coupling constants.

Between 1965 and today all that has happened is 1) verification and more verification of both relativity and the standard model (like the discovery of the higgs) and 2) discovery of dark energy and dark matter.

But now we face a real problem in physics.  We don’t have the clues we had at the turn of the century that led Einstein to his miracle year nor do we have the clues that we had back in 1960 with the particle zoo.  All we have are very small hints and the real extent of the problem is clear.  To get to the energy levels required to create our own dark matter it seems likely we will need energy levels approaching 1,000,000,000 times more than the LHC.  10^-23cm is right around where both the weak force and dark matter are hiding and to pry them out in the open we would need a new LHC that is larger than the earth.  Right now the LHC is many orders of magnitudes hotter than any star, it’s pretty close to the big bang, but to get to where we think we need to is going to be a problem.   Astronomical physics is also a problem, as the cosmic background radiation doesn’t actually go back to the big bang it only goes back to a few hundred thousand years afterwards when the universe cooled down enough to create atoms because before that the universe was opaque.

What is next then?  The web telescope is 8.7b, 13b for ligo, huge telescopes like SKA and EELT are about 2b, Super-Kamiokande is relatively cheap for a few million, the Kepler telescope was also a bargain and a half billion.  But anywhere we look it seems like it will be a costly search.  And we don’t have any plan forward.  There are as many theories for the dark matter as you might like, though the WIMP seems most likely and supersymmetry also seems like a reasonable idea.  However it is hubris to think that humans were meant to understand the universe.  Perhaps true understanding is beyond our reach and that we won’t be able to build a detector, or telescope large enough to find out the true nature of the universe.  For the past 200 years we have been picking off the low lying fruit.  Saul Perlmutter got the last of it with the discovery of dark energy by examining type 2 supernovas.  From now on it seems all the projects will get larger and larger and more and more expensive.  I don’t see any particular reason to think that one way is better than another, a telescope, an underground dark matter detector, space telescope or another gravitational detector.  Theorists right now are spinning new theories but the entire edifice of string theory is so big, it contains not only the current standard model but every possible standard model for every possible universe.  My personal feeling is to keep striving and to continue with all the projects, that means yes building the next LHC, with 10 times the power.   It will be expensive but every path forward is expensive now.  Build another LHC, build another space telescope another super K, and what will have to happen is more of the same.  Today an experimental physicist will never do an experiment on his own.  Because of the cost of modern physics he will only share the first page with hundreds of others.  We will have to continue down the same path, more expensive physics projects but less and less actual experiments as the cost continues to rise for each experiment.

 

Why 21?  Because that’s how far I got.  I might add 1 or 2 later on, then it will be 22 or 23.  I was talking with a sibling of mine about how I quit watching movies because they suck, I don’t watch tv because it sucks too.  I still occasionally read books tho and the reason is there are so many authors so many books it is inevitable that eventually you will find a book that you relish.   Unlike movies where if you are lucky there might be one good movie in a given year, every year there are hundreds of amazing books.  So if you think you might have a similar taste to mine, here’s a book list of some of my favorite sci fi & fantasy books.  I know some of these books are really too common, flowers for algernon, lord of rings, if you haven’t read those yet you probably don’t need my recommendation.  But I believe there might be some books in here someone else might be interested in.  My reading tastes range from the shallow to the deep, not sure if there is a consistent theme to what I like.

top sci fi & fantasy books and why, no particular order with one line explaining why

1. Cugel’s Saga, Jack Vance.  D&D style fantasy complete with greedy main characters
2. ubik, philip k dick.  One of the best sci fi writers with perhaps his greatest book.
3. deepness in the sky, vernor vinge.  An omelet of hard sci fi, characters, plot and actual science.
4. lord of the rings tolkien, he started that sword and sorcery thing
5. 1984, orwell.  no longer the future 1984 is now
5. 20,000 leagues under the sea, jules verne.  great old timey stuff.
6. flowers for algernon, keyes, because we are all algernon.
7. day of the triffids, john wyndham, a great 1950’s plant invasion
8. jonathan strange and mr norrell, susanna clarke, wonderfully written
9. a witch shall be born, robert e howard.  scene of conan freeing himself from crucifixation has never been equaled
10. nine princes in amber, zelazny, this is one of the few “just for fun” series that I enjoy re-reading
11. solaris, stanislaw lem, pyschological sci fi
12. varney the vampire, James Malcolm Rymer and Thomas Peckett Prest, dickens era vampire story, when vampires weren’t cool
13. the descent, jeff long, so claustrophobic
14. first book of swords, fred saberhagen, i like this because fred tries not to be too silly even when ridiculous
15. when gravity fails, george alec effinger, a terrific writer that happens to write sci fi
16. nul-a ae van vogt, it’s the golden age, where men were manly men
17. arcane, carl sherrell.  If you don’t see a unicorn on the cover then it’s the wrong “arcane”
18. marrow, robert reed.  wonderful detailed sub light sci fi book, because sub light speed is always better than warp speed
19. the magus, john fowles.  Is he a wizard or a bullshitter?
20. ash: a secret history, mary gentle.  All the  other world builders are just fakers, this is the real deal.
21. ship of fools, richard paul russo, really is there any better hard sci gene than sub light speed space ships?
22. Ursus of Ultima Thule, Avram Davison.  Reading books by Avram always reminds me of my late father for some reason.

 

 

“The reason we don’t see these funny quantum states that they are interacting with things around them we call that decoherence. The question is does this explain schoedinger’s cat paradox? Absolutely. The cat is being bombarded with air molecules all the time. An awful lot of nonsense is said about quantum mechanics. There are mysterious things about it. But all of them have to do with gravity. If the word gravity doesn’t appear and they say there is something mysterious about quantum mechanics they are selling you something. When we do things in the lab it is beautifully described by quantum mechanics. There’s no difficulty whatsoever. Decoherence solves all of the old paradoxes. This was a point appreciated by Bohr and Heisenberg. Bohr was such a horrible writer that it didn’t really penetrate but it was revived in the 1980’s. The process of measurement is not some ur-different thing. It’s part of nature! A measuring device is made out of the same stuff everything else is made of. There’s no “mysterious consciousness” involved in the process of measurement. There’s no such thing as wave function collapse. Everything is just good old fashioned quantum mechanics. There is something important when you have interactions between small systems and very very big systems, then these quantum coherences can be very quickly lost. That’s the reason why classical physics emerges, it’s why measurements yield well defined answers.”
Nima Arkani-Hamed speaking at the Cornell Messanger Lectures June 6, 2016.
I’ll probably save this quote in my blog too, so I can reference it later when I feel the need to talk sense to copenhagen quantum wooers.