All posts by StenBlog

Things we agree on…

Although many survey questions you hear about show close to a 50/50 split in public opinion, there are still many questions that offer nearly unanimous agreement and probably help to define who we are as a Nation in terms of core values and beliefs. I have always wondered what these key issues are, so I gathered up as many of these “over-80 percent” responses as I could easily locate back in 2014. They come in two kinds of statistical samples: biased and un-biased.

Un-Biased Surveys

The only correct way to survey people’s opinions is through a carefully designed randomized survey to eliminate biases that would skew the results. The answers you get from these surveys are probably the most reliable. After each question I give the response and its percentage, the number of people in the sample, the name of the surveyor, and the date. Many of these surveys are by land-line telephone, so a fair question is: Are people that answer their land-lines typical of the general population today?

Do you use your seatbelt? Yes=98 percent (1500, Washington state poll, Traffic Safety Commission 9/23/2010)

Do you believe that man-made climate change is real? Yes=97 percent (1372 scientists, National Academy of Science, 6/22/2010) Note. Pew Research survey in 2016 of 1019 US adults found that only 65% believed this was true.

There are now all too many examples of significant climate change..How many more do we need? (Credit: NATO Review)

Do you play video games? Yes = 97 percent (1102 children ages12-17, Pew Internet and American Life Project, 9/17/2008)

Do you broadcast your location on the Internet using location-based services? No = 96 percent (1500, Forrester Research, 8/30/2010)

Do you believe in a God? Yes = 95 percent (1500, Gallop Poll, 3/29/2001) Note Gallup Poll 2016 shows that 89% now believe in God. Related to this is the Pew Research poll in 2015 that showed 72% of people believed in an afterlife. A Roper Survey in 2011 found 40% of US adults believed in ghosts, but this belief has been declining since 2005 when it was 48%.

Do you want stronger protection for your Internet privacy? Yes=94 percent (2117, Pew Internet and American Life Project, 5/2000 ) Note: In April 2017, President Trump signed an executive order that now allows Internet Service Providers to sell your private information without telling you!

Are the Arts vital to providing a well-rounded education to children? Yes=93 percent (1000, Harris Poll, 6/13/2005)

Would you vote for a woman for President? Yes=92 percent (1229, CBS News/New York Times, 2/5/2006 ) In the 2016 presidential election, over 3 million more people voted for the female candidate than the male candidate.

Would you stop doing business with a company because of bad service? Yes = 87 percent (2000, Harris Interactive,10/8/2008)

Do you use the print version of the Yellow Pages phone book? Yes = 87 percent (9008, Knowledge Network/SRI Industry Usage Study, 2/26/2008)

Do you think that English should be the official language of the US? Yes= 87 percent (1000, Rassmussen Report, 5/11 /2010) Note, in 2016 a Pew Survey found that 90% of American adults thought that English should be the official language.

Do you think it is important for America to use and develop solar energy? Yes=92 percent (1000 online survey, SCHOTT Solar Barometer; Kelton Research, 10/8/2009)

Do you think the federal government is broken? Yes= 86 percent (1023, CNN/Opinion Research Poll, 2/22/2010). Note in 2015, 75% of Gallup Survey believed that widespread government corruption exists. President Trump was elected to shake up the government and ‘drain the swamp’, only to demonstrate that he was himself a major corrupting influence supported by intense Russian influence in the election.

Would you prefer to stop using paper and go Green? Yes=85 percent (1000, Harris Interactive/DocuSign Inc, 6/30/2010)

Should you have to prove you are a citizen before you receive healthcare in the U.S.? Yes=83 percent (1500, Rassmussen Report, 9/7/2009)

Do you shop ‘Green? Yes = 82 percent (1000, Opinion Research Corporation, 2/6/2009)

Do you favor legalizing marijuana for medical use? Yes=81 percent (1083, ABC/Washington Post, 1/18/2010)

Is a car a necessity? Yes=86 percent (2967, Pew Research, 4/2/2009)

Do you think the government will make progress on important issues? No=90 percent (1010, Pew Research, 9/23/2010)

In the future, will computers be able to talk to humans? Yes=81 percent (1546, Pew Research, 6/22/2010 )

Do you know what Twitter is? Yes= 85 percent (1007, Pew Research, 7/15/2010)

Is President Obama a Muslim? No = 82 percent (3003 adults; Pew Research 8/19/2010) Note by 2015 this had fallen to 79% (CNN/ORC Poll). This truly shows that nearly 30% of American adults are certifiably as dumb as dust. This belief among GOP voters is nearly 3 times higher than for democrats.

Has science had a positive effect on society? Yes = 84 percent (2001, Pew Research, 7/9/2009)

Is climate change a serious threat and are you willing to make sacrifices to combat it? Yes=80 percent (1000, Institution of Civil Engineers, 11/20/2009). President Trump’s official position is that climate change science is a Chinese hoax.

Do you live in a house with at least one cellphone? Yes = 90 percent (3001, Pew Research Center, 2/4/2011) Note in 2015 the Pew Research Center found that 64% of American adults owned a smartphone.

Will you be eating Thanksgiving meal with family? Yes= 89 percent (2691, USA Today, 11/30/2011)

Did you make a good investment getting your undergraduate degree? Yes= 89 percent (1500, American Council on Education Winston Group survey, 12/30/2010)

Biased but Interesting Surveys

Biased surveys a not regulated (a person can vote multiple times) and often ask you to vote online, or are conducted by institutions that have a point to make and could be suspected of selecting in advance the people they want to survey that are like-minded (e.g. Fox News). In the results below I have selected CNN.com’s daily online voting results because they were easily available. CNN readers are in equal shares, Liberal, Moderate and Conservative. In addition 50 percent are Democrats and 16 percent are Republicans. Of course ,all have access to the internet and are not surveyed by land-line telephone so they probably represent a younger population.

Do you think Japan should become a permanent member of the United Nations Security Council? “ Yes = 94 percent (924,421, 4/12/2005 )

Do you know how you will vote in the mid-term elections? Yes=90 percent (30799, 10/21/2010 )

Is it time to break out of the two-party political system? Yes = 84 percent (26837, 10/26/2010)

Do political TV ads influence your vote? Yes = 83 percent(70588, 10/27/2010)

Did you brave the crowds and shop on Black Friday? No=84 percent (112322, 11/27/2010)

What do you think of a publisher’s decision to remove the N-word from Huckleberry Finn? Disapprove = 92 percent (44377, 1/7/2011)

Do you think there may be life on planets other than Earth? Yes = 88 percent (243250, 5/22/2011).

Is raising a child free of gender roles a good idea? No=85 percent (198329, 5/27/2011)

Do you approve of the performance of your congressional representatives? No=86 percent (123776, 8/3/2011) Note in 2017 the Rassmusen Survey found that 75% of adults gave Congress a poor rating. So we like the Congressperson we voted for, but dislike everyone else and what they do.

Have you lost confidence in the ability of world leaders to tackle economic problems? Yes=86 percent (187969, 9/16/2011)

Should states require welfare recipients to pass drug tests? Yes = 80 percent (170382, 10/26/2011)

Do you snack on grocery store food before you buy it?
No=89 percent (59894, 11/4/2011)

Are you ready to “boot out” your representative in Congress?
Yes=81 percent (89916, 12/10/2011)

Should racist remarks be subject to criminal prosecution?
No=86 percent (106918, 12/22/2011)

Should convicted murderers be eligible for full pardons?
No = 86 percent (86970, 1/12/2012)

Things we should agree on but don’t.

There are also many issues we should agree on but don’t. It doesn’t matter how much money we invest in ‘public education’. The general public simply doesn’t get it on many significant issues…and they vote accordingly. Here are some of my favorites, sad to say.

Does Ebola spread easily? No=27 percent (1025, Harvard School of Public Health, 8/13/2014). This is a case of fear overcoming reason and evidence.

Are childhood vaccines safe and effective? Yes=53 percent (1012, AP/GFK Poll, 3/24/2014). This is another case of fear overcoming evidence, but with potentially devastating results if too many people ‘opt out’.

Did the universe begin with a huge explosion? Yes= 38 percent (1500, National Science Board,2014 ). This is a case of personal belief and religious fundamentalism overcoming evidence and reasoned discussion. Even the Catholic Pope finds no contradiction with believing the scientific story!

Have humans and other living things evolved over time? Yes=60 percent ( 1983, Pew Research, 3/8/2013). Again, religious fundamentalism and pseudoscience have biased American public thinking.

Would you support a candidate who advocate carbon emission reduction? Yes=68 percent (2105, University of Texas, 9/4/2014). This is directly connected to the public’s lukewarm belief in climate change and the massive negative campaigning by the GOP and industrial lobbyists. In 2016 we elected a president who sides with industry and climate change deniers and is now dismantling both the EPA and canceling all research on climate change at many governmental institutions.

Check back here on Wednesday, April 12 for my next topic!

Glueballs anyone?

Today, physicists are both excited and disturbed by how well the Standard Model is behaving, even at the enormous energies provided by the CERN Large Hadron Collider. There seems to be no sign of the expected supersymmetry property that would show the way to the next-generation version of the Standard Model: Call it V2.0. But there is another ‘back door’ way to uncover its deficiencies. You see, even the tests for how the Standard Model itself works are incomplete, even after the dramatic 2012 discovery of the Higgs Boson! To see how this backdoor test works, we need a bit of history.

Glueballs found in a quark-soup (Credit: Alex Dzierba, Curtis Meyer and Eric Swanson)

Over fifty years ago in 1964, physicists Murray Gell-Mann at Caltech and George Zweig at CERN came up with the idea of the quark as a response to the bewildering number of elementary particles that were being discovered at the huge “atom smasher” labs sprouting up all over the world. Basically, you only needed three kinds of elementary quarks, called “up,” “down” and “strange.” Combining these in threes, you get the heavy particles called baryons, such as the proton and neutron. Combining them in twos, with one quark and one anti-quark, you get the medium-weight particles called the mesons. In my previous blog, I discussed how things are going with testing the quark model and identifying all of the ‘missing’ particles that this model predicts.

In addition to quarks, the Standard Model details how the strong nuclear force is created to hold these quarks together inside the particles of matter we actually see, such as protons and neutrons. To do this, quarks must exchange force-carrying particles called gluons, which ‘glue’ the quarks together in to groups of twos and threes. Gluons are second-cousins to the photons that transmit the electromagnetic force, but they have several important differences. Like photons, they carry no mass, however unlike photons that carry no electric charge, gluons carry what physicist call color-charge. Quarks can be either ‘red’, ‘blue’ or ‘green’, as well as anti-red, anti-green and anti-blue. That means that quarks have to have complex color charges like (red, anti-blue) etc. Because the gluons carry color charge, unlike photons which do not interact with each other, gluons can interact with each other very strongly through their complicated color-charges. The end result is that, under some circumstances, you can have a ball of gluons that resemble a temporarily-stable particle before they dissipate. Physicists call these glueballs…of course!

Searching for Glueballs.

Glueballs are one of the most novel, and key predictions of the Standard Model, so not surprisingly there has been a decades-long search for these waifs among the trillions of other particles that are also routinely created in modern particle accelerator labs around the world.

Example of glueball decay into pi mesons.

Glueballs are not expected to live very long, and because they carry no electrical charge they are perfectly neutral particles. When these pseudo-particles decay, they do so in a spray of other particles called mesons. Because glueballs consist of one gluon and one anti-gluon, they have no net color charge. From the various theoretical considerations, there are 15 basic glueball types that differ in what physicists term parity and angular momentum. Other massless particles of the same general type also include gravitons and Higgs bosons, but these are easily distinguished from glueball states due to their mass (glueballs should be between 1 and 5GeV) and other fundamental properties. The most promising glueball candidates are as follows:

Scalar candidates: f0(600), f0(980), f0(1370), f0(1500), f0(1710), f0(1790)
Pseudoscalar candidates: η(1405), X(1835), X(2120), X(2370), X(2500)
Tensor candidates: fJ(2220), f2(2340)

By 2015, the f-zero(1500) and f-zero(1710) had become the prime glueball candidates. The properties of glueball states can be calculated from the Standard Model, although this is a complex undertaking because glueballs interact with nearby quarks and other free gluons very strongly and all these factors have to be considered.

On October 15, 2015 there was a much-ballyhooed announcement that physicists had at last discovered the glueball particle. The articles cited Professor Anton Rebhan and Frederic Brünner from TU Wien (Vienna) as having completed these calculations, concluding that the f-zero(1710) was the best candidate consistent with experimental measurements and its predicted mass. More rigorous experimental work to define the properties and exact decays of this particle are, even now, going on at the CERN Large Hadron Collider and elsewhere.

So, between the missing particles I described in my previous blog, and glueballs, there are many things about the Standard Model that still need to be tested. But even with these predictions confirmed, physicists are still not ‘happy campers’ when it comes to this grand theory of matter and forces. Beyond these missing particles, we still need to have a deeper understanding of why some things are the way they are, and not something different.

Check back here on Wednesday, April 5 for my next topic!

Crowdsourcing Gravity

The proliferation of smartphones with internal sensors has led to some interesting opportunities to make large-scale measurements of a variety of physical phenomena.

The iOS app ‘Gravity Meter’ and its android equivalent have been used to make  measurements of the local surface acceleration, which is nominally 9.8 meters/sec2. The apps typically report the local acceleration to 0.01 (iOS) or even 0.001 (android) meters/secaccuracy, which leads to two interesting questions: 1)How reliable are these measurements at the displayed decimal limit, and 2) Can smartphones be used to measure expected departures from the nominal surface acceleration due to Earth rotation? Here is a map showing the magnitude of this (centrifugal) rotation effect provided by The Physics Forum.

As Earth rotates, any object on its surface will feel a centrifugal force directed outward from the center of Earth and generally in the direction of local zenith. This causes Earth to be slightly bulged-out at the equator compared to the poles, which you can see from the difference between its equatorial radius of 6,378.14 km versus its polar radius of 6,356.75 km: a polar flattening difference of 21.4 kilometers. This centrifugal force also has an effect upon the local surface acceleration  by reducing it slightly at the equator compared to the poles. At the equator, one would measure a value for ‘g’ that is about 9.78 m/sec2 while at the poles it is about 9.83 m/sec2. Once again, and this is important to avoid any misconceptions, the total acceleration defined as gravity plus centrifugal is reduced, but gravity is itself not changed because from Newton’s Law of Universal Gravitation, gravity is due to mass not rotation.

Assuming that the smartphone accelerometers are sensitive enough, they may be able to detect this equator-to-pole difference by comparing the surface acceleration measurements from observers at different latitudes.

 

Experiment 1 – How reliable are ‘gravity’ measurements at the same location?

To check this, I looked at the data from several participating classrooms at different latitudes, and selected the more numerous iOS measurements with the ‘Gravity Meter’ app. These data were kindly provided by Ms. Melissa Montoya’s class in Hawaii (+19.9N), George Griffith’s class in Arapahoe, Nebraska (+40.3N), Ms. Sue Lamdin’s class in Brunswick, Maine (+43.9N), and Elizabeth Bianchi’s class in Waldoboro, Maine (+44.1N).

All four classrooms measurements, irrespective of latitude (19.9N, 40.3N, 43.9N or 44.1N) showed distinct ‘peaks’, but also displayed long and complicated ‘tails’, making these distributions not Gaussian as might be expected for random errors. This suggests that under classroom conditions there may be some systematic effects introduced from the specific ways in which students may be making the measurements, introducing  complicated and apparently non-random,  student-dependent corrections into the data.

A further study using the iPad data from Elizabeth Bianchi’s class, I discovered that at least for iPads using the Gravity Sensor app, there was a definite correlation between when the measurement was made and the time it was made during a 1.5-hour period. This resembles a heating effect, suggesting that the longer you leave the technology on before making the measurement, the larger will be the measured value. I will look into this at a later time.

The non-Gaussian behavior in the current data does not make it possible to assign a normal average and standard-deviation to the data.

 

Experiment 2 – Can the rotation of Earth be detected?

Although there is the suggestion that in the 4-classroom data we could see a nominal centrifugal effect of about the correct order-of-magnitude, we were able to get a large sample of individual observers spanning a wide latitude range, also using the iOS platform and the same ‘Gravity Meter’ app. Including the median values from the four classrooms in Experiment 1, we had a total of 41 participants: Elizabeth Abrahams, Jennifer Arsenau, Dorene Brisendine, Allen Clermont, Hillarie Davis, Thom Denholm, Heather Doyle, Steve Dryer, Diedra Falkner, Mickie Flores, Dennis Gallagher, Robert Gallagher, Rachael Gerhard, Robert Herrick, Harry Keller, Samuel Kemos, Anna Leci, Alexia Silva Mascarenhas, Alfredo Medina, Heather McHale, Patrick Morton, Stacia Odenwald, John-Paul Rattner, Pat Reiff, Ghanjah Skanby, Staley Tracy, Ravensara Travillian, and Darlene Woodman.

The scatter plot of these individual measurements is shown here:

The red squares are the individual measurements. The blue circles are the android phone values. The red dashed line shows the linear regression line for only the iOS data points assuming each point is equally-weighted. The solid line is the predicted change in the local acceleration with latitude according to the model:

G =   9.806   –  0.5*(9.832-9.78)*Cos(2*latitude)    m/sec2

where the polar acceleration is 9.806 m/sec2 and the equatorial acceleration is 9.780 m/sec2. Note: No correction for lunar and solar tidal effects have been made since these are entirely undetectable with this technology.

Each individual point has a nominal variation of +/-0.01 m/sec2 based on the minimum and maximum value recorded during a fixed interval of time. It is noteworthy that this measurement RMS is significantly smaller than the classroom variance seen in Experiment 1 due to the apparently non-Gaussian shape of the classroom sampling. When we partition the iOS smartphone data into 10-degree latitude bins and take the median value in each bin we get the following plot, which is a bit cleaner:

The solid blue line is the predicted acceleration. The dashed black line is the linear regression for the equally-weighted individual measurements. The median values of the classroom points are added to show their distribution. It is of interest that the linear regression line is parallel, and nearly coincident with, the predicted line, which again suggests that Earth’s rotation effect may have been detected in this median-sampled data set provided by a total of 37 individuals.

The classroom points clustering at ca +44N represent a total of 36 measures representing the plotted median values, which is statistically significant. Taken at face value, the classroom data would, alone, support the hypothesis that there was a detection of the rotation effect, though they are consistently 0.005 m/sec2 below the predicted value at the mid-latitudes. The intrinsic variation of the data, represented by the consistent +/-0.01 m/sec2 high-vs-low range of all of the individual samples, suggests that this is probably a reasonable measure of the instrumental accuracy of the smartphones. Error bars (thin vertical black lines) have been added to the plotted median points to indicate this accuracy.

The bottom-line seems to be that it may be marginally possible to detect the Earth rotation effect, but precise measurements at the 0.01 m/sec2 level are required against what appears to be a significant non-Gaussian measurement background. Once again, some of the variation seen at each latitude may be due to how warm the smartphones were at the time of the measurement. The android and iOS measurements do seem to be discrepant with the android measurements leading to a larger measurement variation.

Check back here on Wednesday, March 29 for the next topic!

Fifty Years of Quarks!

Today, physicists are both excited and disturbed by how well the Standard Model is behaving, even at the enormous energies provided by the CERN Large Hadron Collider. There seems to be no sign of the expected supersymmetry property that would show the way to the next-generation version of the Standard Model: Call it V2.0. But there is another ‘back door’ way to uncover its deficiencies. You see, even the tests for how the Standard Model itself works are incomplete, even after the dramatic 2012 discovery of the Higgs Boson! To see how this backdoor test works, we need a bit of history.

Over fifty years ago in 1964, physicists Murray Gell-Mann at Caltech and George Zweig at CERN came up with the idea of the quark as a response to the bewildering number of elementary particles that were being discovered at the huge “atom smasher” labs sprouting up all over the world. Basically, you only needed three kinds of elementary quarks, called “up,” “down” and “strange.” Combining these in threes, you get the heavy particles called baryons, such as the proton and neutron. Combining them in twos, with one quark and one anti-quark, you get the medium-weight particles called the mesons.

This early idea was extended to include three more types of quarks, dubbed “charmed,” “top” and “bottom” (or on the other side of the pond, “charmed,” “truth” and “beauty”) as they were discovered in the 1970s. These six quarks form three generations — (U, D), (S, C), (T, B) — in the Standard Model.

Particle tracks at CERN/CMS experiment (credit: CERN/CMS)

Early Predictions

At first the quark model easily accounted for the then-known particles. A proton would consist of two up quarks and one down quark (U, U, D), and a neutron would be (D, D, U). A pi-plus meson would be (U, anti-D), and a pi-minus meson would be (D, anti-U), and so on. It’s a bit confusing to combine quarks and anti-quarks in all the possible combinations. It’s kind of like working out all the ways that a coin flipped three times give you a pattern like (T,T,H) or (H,T,H), but when you do this in twos and threes for U, D and S quarks, you get the entire family of the nine known mesons, which forms one geometric pattern in the figure below, called the Meson Nonet.

The basic Meson Nonet (credit: Wikimedia Commons)

If you take the three quarks U, D and S and combine them in all possible unique threes, you get two patterns of particles shown below, called the Baryon Octet (left) and the Baryon Decuplet (right).

Normal baryons made from three-quark triplets

The problem was that there was a single missing particle in the simple 3-quark baryon pattern. The Omega-minus (S,S,S) at the apex of the Baryon Decuplet was nowhere to be found. This slot was empty until Brookhaven National Laboratory discovered it in early 1964. It was the first indication that the quark model was on the right track and could predict a new particle that no one had ever seen before. Once the other three quarks (C, T and B) were discovered in the 1970s, it was clear that there were many more slots to fill in the geometric patterns that emerged from a six-quark system.

The first particles predicted, and then discovered, in these patterns were the J/Psi “charmonium” meson (C, anti-C) in 1974, and the Upsilon “bottomonium” meson (B, anti-B) in 1977. Apparently there are no possible top mesons (T, anti-T) because the top quark decays so quickly it is gone before it can bind together with an anti-top quark to make even the lightest stable toponium meson!

The number of possible particles that result by simply combining the six quarks and six anti-quarks in patterns of twos (mesons) is exactly 39 mesons. Of these, only 26 have been detected as of 2017. These particles have masses between 4 and 11 times more massive than a single proton!

For the still-heavier three-quark baryons, the quark patterns predict 75 baryons containing combinations of all six quarks. Of these, the proton and neutron are the least massive! But there are 31 of these predicted baryons that have not been detected yet. These include the lightest missing particle, the double charmed Xi (U,C,C) and the bottom Sigma (U, D, B), and the most massive particles, called the charmed double-bottom Omega (C, B, B) and the triple-bottom omega (B,B,B). In 2014, CERN/LHC announced the discovery of two of these missing particles, called the bottom Xi baryons (B, S, D), with masses near 5.8 GeV.
To make life even more interesting for the Standard Model, other combinations of more than three quarks are also possible.

Exotic Baryons
A pentaquark baryon particle can contain four quarks and one anti-quark. The first of these, called the Theta-plus baryon, was predicted in 1997 and consists of (U, U, D, D, anti-S). This kind of quark package seems to be pretty rare and hard to create. There have been several claims for a detection of such a particle near 1.5 GeV, but experimental verification remains controversial. Two other possibilities called the Phi double-minus (D, D, S, S, anti-U) and the charmed neutral Theta (U, U, D, D, anti-C) have been searched for but not found.

Comparing normal and exotic baryons (credit: Quantum Diaries)

There are also tetraquark mesons, which consist of four quarks. The Z-meson (C, D, anti-C, anti-U) was discovered by the Japanese Bell Experiment in 2007 and confirmed in 2014 by the Large Hadron Collider at 4.43 GeV, hence the proper name Z(4430). The Y(4140) was discovered at Fermilab in 2009 and confirmed at the LHC in 2012 and has a mass 4.4 times the proton’s mass. It could be a combination of charmed quarks and charmed anti-quarks (C, anti-C, C, anti-C). The X(3830) particle was also discovered by the Japanese Bell Experiment and confirmed by other investigators, and could be yet another tetraquark combination consisting of a pair of quarks and anti-quarks (q, anti-q, q, anti-q).

So the Standard Model, and the six-quark model it contains, makes specific predictions for new baryon and meson states to be discovered. All totaled, there are 44 ordinary baryons and mesons that remain to be discovered! As for the ‘exotics’ that opens up a whole other universe of possibilities. In theory, heptaquarks (5 quarks, 2 antiquarks), nonaquarks (6 quarks, 3 antiquarks), etc. could also exist.

At the current pace of a few particles per year or so, we may finally wrap up all the predictions of the quark model in the next few decades. Then we really get to wonder what lies beyond the Standard once all the predicted particle slots have been filled. It is actually a win-win situation, because we either completely verify the quark model, which is very cool, or we discover anomalous particles that the quark model can’t explain, which may show us the ‘backdoor’ way to the Standard Model v.2.0 that the current supersymmetry searches seem not to be providing us just yet.

Check back here on Wednesday, March 22 for the next topic!

Hohmann’s Tyrany

It really is a shame. When all you have is a hammer, everything else looks like a nail. This also applies to our current, international space programs.

We have been using chemical rockets for centuries, but since the advent of V2s and the modern space age, these brute-force and cheap work horses have been the main propulsion technology we use to go just about everywhere in the solar system. But this amounts to thinking that one technology can span all of our needs, and the trillions of cubic miles that encompass interplanetary space.

We pay a huge price for this belief.

Chemical rockets have their place in space travel. They are fantastic ways of delivering HUGE thrusts quickly; the method par excellance for getting us off this planet and paying the admission ticket to space.  No other known propulsion technology is as cheap, simple, and technologically elegant as chemical propulsion in this setting.  Applying this same technology to interplanetary travel beyond the moon is quite another thing, and sets in motion an escalating series of difficult problems.

Every interplanetary spacecraft launched so far to travel to each of the planets in our solar system works on the exact same principle. Give the spacecraft a HUGE boost to get it off the launch pad, and with enough velocity to reach the distant planet, then cut the engines off after a few minutes so the spacecraft can literally coast the whole way. With a few more ‘Delta-V’ changes, this is called the minimum –energy trajectory or for rocket scientists the Hohmann Transfer orbit. It is designed to get you there, not in the shortest time, but using the least amount of energy. In propulsion, energy is money. We use souped-up Atlas rockets at a few hundred million dollars a pop to launch space craft to the outer planets. We don’t use  even larger and expensive Saturn V rockets that deliver even more energy for a dramatically-shorter ride.

If you bank on taking the slow-boat to Mars rather than a more energetic ride, this leads to all sorts of problems. The biggest of these is that the inexpensive 220-day journeys let humans build up all sorts of nasty medical problems that short 2-week trips would completely eliminate. In fact, the entire edifice of the $150 billion International Space Station is there to explore the extended human stays in space that are demanded by Hohmann Transfer orbits and chemical propulsion. We pay a costly price to keep using cheap chemical rockets that deliver long stays in space, and cause major problems that are expensive to patch-up afterwards. The entire investment in the ISS could have been eliminated if we focused on getting the travel times in space down to a few weeks.

You do not need Star Trek warp technology to do this!

Since the 1960s, NASA engineers and academic ‘think tanks’ have designed nuclear rocket engines and ion rocket engines, both show enormous promise in breaking the hegemony of chemical transportation. The NASA nuclear rocket program began in the e arly-1960s and built several operational prototypes, but the program was abandoned in the late 1960s because nuclear rockets were extremely messy, heavy, and had a nasty habit of slowly vaporizing the nuclear reactor and blowing it out the rocket engine!  Yet, Wernher  Von Braun designed a Mars expedition for the 1970s in which several,  heavy 100-ton nuclear motors would be placed in orbit by a Saturn V and then incorporated into an set of three interplanetary transports. This program was canceled when the Apollo program was ended and there was no longer a conventional need for the massive Saturn V rockets. But ion rockets continued to be developed and today several of these have already been used on interplanetary spacecraft like Deep Space 1 and Dawn. The plans for humans on Mars in 2030s rely on ion rocket propulsion powered by massive solar panels.

Unlike chemical rockets, which limit spacecraft speeds to a few kilometers/sec, ion rockets can be developed with speeds up to several thousand km/sec. All that they need is more thrust, and to get that they need low-mass power plants in the gigawatt range. ‘Rocket scientists’ gauge engine designs based on their Specific Impulse, which is the exhaust speed divided by the acceleration of gravity on Earth. Chemical rockets can only provide SIs of 300 seconds, but ion engine designs can reach 30,000 seconds or more! With these engine designs, you can travel to Mars in SIX DAYS, and a jaunt to Pluto can take a neat 2 months! Under these conditions, most of the problems and hazards of prolonged human travel in space are eliminated.

But instead of putting our money into perfecting these engine designs, we keep building chemical rockets and investing billions of dollars trying to keep our long-term passengers alive.

Go figure!!!

Check back here on Friday, March 17 for a new blog!

 

The Mystery of Gravity

In grade school we learned that gravity is an always-attractive force that acts between particles of matter. Later on, we learn that it has an infinite range through space, weakens as the inverse-square of the distance between bodies, and travels exactly at the speed of light.

But wait….there’s more!

 

It doesn’t take a rocket scientist to remind you that humans have always known about gravity! Its first mathematical description as a ‘universal’ force was by Sir Isaac Newton in 1666. Newton’s description remained unchanged until Albert Einstein published his General Theory of Relativity in 1915. Ninety years later, physicists, such as Edward Witten, Steven Hawkings, Brian Greene and Lee Smolin among others, are finding ways to improve our description of ‘GR’ to accommodate the strange rules of quantum mechanics. Ironically, although gravity is produced by matter, General Relativity does not really describe matter in any detail – certainly not with the detail of the modern quantum theory of atomic structure. In the mathematics, all of the details of a planet or a star are hidden in a single variable, m, representing its total mass.

 

The most amazing thing about gravity is that is a force like no other known in Nature. It is a property of the curvature of space-time and how particles react to this distorted space. Even more bizarrely, space and time are described by the mathematics of  GR as qualities of the gravitational field of the cosmos that have no independent existence. Gravity does not exist like the frosting on a cake, embedded in some larger arena of space and time. Instead, the ‘frosting’ is everything, and matter is embedded and intimately and indivisibly connected to it. If you could turn off gravity, it is mathematically predicted that space and time would also vanish! You can turn off electromagnetic forces by neutralizing the charges on material particles, but you cannot neutralize gravity without eliminating spacetime itself.  Its geometric relationship to space and time is the single most challenging aspect of gravity that has prevented generations of physicists from mathematically describing it in the same way we do the other three forces in the Standard Model.

Einstein’s General Relativity, published in 1915, is our most detailed mathematical theory for how gravity works. With it, astronomers and physicists have explored the origin and evolution of the universe, its future destiny, and the mysterious landscape of black holes and neutron stars. General Relativity has survived many different tests, and it has made many predictions that have been confirmed. So far, after 90 years of detailed study, no error has yet been discovered in Einstein’s original, simple theory.

Currently, physicists have explored two of its most fundamental and exotic predictions: The first is that gravity waves exist and behave as the theory predicts. The second is that a phenomenon called ‘frame-dragging’ exists around rotating massive objects.

Theoretically, gravity waves must exist in order for Einstein’s theory to be correct. They are distortions in the curvature of spacetime caused by accelerating matter, just as electromagnetic waves are distortions in the electromagnetic field of a charged particle produced by its acceleration. Gravity waves carry energy and travel at light-speed. At first they were detected indirectly. By 2004, astronomical bodies such as the  Hulse-Taylor orbiting pulsars were found to be losing energy by gravity waves emission at exactly the predicted rates. Then  in 2016, the  twin  LIGO gravity wave detectors detected the unmistakable and nearly simultaneous pulses of geometry distortion created by colliding black holes billions of light years away.

Astronomers also detected by 1997 the ‘frame-dragging’ phenomenon in  X-ray studies of distant black holes. As a black hole (or any other body) rotates, it actually ‘drags’ space around with it. This means that you cannot have stable orbits around a rotating body, which is something totally unexpected in Newton’s theory of gravity. The  Gravity Probe-B satellite orbiting Earth also confirmed in 2011 this exotic spacetime effect at precisely the magnitude expected by the theory for the rotating Earth.

Gravity also doesn’t care if you have matter or anti-matter; both will behave identically as they fall and move under gravity’s influence. This quantum-scale phenomenon was searched for at the Large Hadron Collider ALPHA experiment, and in 2013 researchers placed the first limits on how matter and antimatter ‘fall’ in Earth’s gravity. Future experiments will place even more stringent limits on just how gravitationally similar matter and antimatter are. Well, at least we know that antimatter doesn’t ‘fall up’!

There is only one possible problem with our understanding of gravity known at this time.

Applying general relativity, and even Newton’s Universal Gravitation, to large systems like galaxies and the universe leads to the discovery of a new ingredient called Dark Matter. There do not seem to be any verifiable elementary particles that account for this gravitating substance. Lacking a particle, some physicists have proposed modifying Newtonian gravity and general relativity themselves to account for this phenomenon without introducing a new form of matter. But none of the proposed theories leave the other verified predictions of general relativity experimentally intact. So is Dark Matter a figment of an incomplete theory of gravity, or is it a here-to-fore undiscovered fundamental particle of nature? It took 50 years for physicists to discover the lynchpin particle called the Higgs boson. This is definitely a story we will hear more about in the decades to come!

There is much that we now know about gravity, yet as we strive to unify it with the other elementary forces and particles in nature, it still remains an enigma. But then, even the briefest glance across the landscape of the quantum world fills you with a sense of awe and wonderment at the improbability of it all. At its root, our physical world is filled with improbable and logic-twisting phenomena and it simply amazing that they have lent themselves to human logic to the extent that they have!

 

Return here on Monday, March 13 for my next blog!

A Family Resurrection

When someone tells you that they are a family geneaologist, your first reaction is to gird yourself for a boring conversation about begats that will sound something like a chapter out of the Old Testament Genesis. What you probably don’t understand is the compulsion that drives us in this task.

A pretty little scene from one of my ancestral places near Uddevalla!

5,176 – That’s the number of people I have helped bring back from oblivion through my labors. There is an ineffable feeling of deep satisfaction in having tracked them down through the countless Swedish church records spanning over 600 years of  history. Every one recovered and named was a personal victory for me against the forgetfulness of time and history. Ancient Egyptians believed that if you removed a person’s name from monuments, or ceased to speak it, that the person’s spirit would actually cease to exist.  That is why so many pharaoh’s defaced their predecessor’s monuments by removing their names. To counter this eternal death, all you have to do is again speak their name!

I, personally, have resurrected over 15 families who I never knew existed. I can now name their parents, their children, when and where they were born and died, how often they pulled up roots in one town and moved to another. I know where and when they lived among the countless towns and farms in rural Sweden. I can also anticipate what major stories and geopolitical issues must have been the small talk around dinner tables and among their fellow farm laborers in the fields.

Everyone loves the thrill of the hunt, the stalking of prey, and the final moment of satisfaction at the completion of the pursuit. For a genealogist, we hunt through historical records in pursuit of a single  individual. Pouring through a record containing a thousand names, we spot the birth of an ancestor. The accompanying census record tips us off about his family unit captured in hand-written names, birth dates and places. A bit more work among the records of that moment clinches the number of children and where the family had last been in its travels. Looking forward, we recover the names of the grandparents, the birth and death dates and places of the parents, marriages, when the children left home, and where they later wound up as their own lives played out in the course of time.

Countess ‘Aha’ moments reward you as you meticulously slog through these records, and step-by-step recover a parent, a child, a place, a history. In doing so, you enter the acute fogginess of an alternate state of mind. The reward for this compulsion carries you on for many days until at last your labors are completed and you sit back and admire what you have just accomplished. There on your pages of notes, an entire family has been brought back from the depths of time. Like a diadem recovered from the soil, you can now admire the texture of this family and see it as an organic and living thing in space and time. As little as two weeks ago, you never even knew they existed. For years and even centuries before that, these ancestors lay buried in time and utterly forgotten by the living. They slumbered in the many fragmented pages of a hundred church books spread across countless square miles of Sweden until you, one day, decided to resurrect them and tell their story.

The curious, but typical story of Eric Juhlin!

Eric Ulric Juhlin, my second great great uncle, was born on July 4, 1823 to my third great grandfather Magnus Juhlin and his wife Britta Ulrica Gadd, in the town of Tutaryd, Sweden.

In 2010 I only knew Eric existed from the town’s census record that revealed the 11 children of my distant grandfather Magnus Juhlin, which were listed neatly in their own little rows of data. Eric was the twin to Petrus Juhlin who, sadly, died three months later as was a common risk for young children and infants in 18th century rural Sweden.

Well, Eric eventually met Eva Cajsa Svensdotter from Ljungby, Sweden; The exact details of how they met are obscure. But they settled for a time in the town of Halmstad, where on March 6, 1855 they had their first child Clara. Returning to Tutaryd in 1856, for the next 22 years they gave birth to six more children: Ida Regina, Ferdinand, Hedvig, Davida, Ulrica, and Gustaf Adolph. By the time their seventh-and- last child Carl Leonard was born in 1878, Eric was by that time 55 years old and Eva Caisa had turned 48 only 5 months later.

This family was singularly unlucky in raising their children to adulthood. Ferdinand died at the age of only five years. Carl Leonard made it to age 3, and Gustav Adolph, with an impressive King’s name, died at age 8. But there were also some hopeful stories too among their more fortunate siblings who they barely got to know.

Ida Regina did survive childhood and went on to marry Magnus Adolph Persson. Settling in the southern town of Hjämarp, they raised three sons and three daughters who all grew up and lived to old age. Magnus eventually died in 1930 at the age of 69 followed by Ida ten years later at the age of 83. Ida’s 16-year-old sister Ulrica, decided for whatever reason to emmigrate to the United States, where she eventually met and married her husband Fredrick William Picknell in 1893. Settling in Champaign, Illinois, they raised three sons: Percy Gordon, Frederick and Charles. Sadly, Ulrica died in 1915 at the age of 45. Her husband survived her another 30 years. Their three sons went on to form their own families until they, themselves, passed into history; the last of them, Frederick exiting this world in Toledo, Ohio on Halloween Day, 1986. But each of them managed to cast yet another generation into futurity, and through their children, colonized the years between 1920 and 2012. One of them, Harry Gene Picknell lived in Bethesda, Maryland only a stone’s throw from my own front door…but I never got to meet him.

What became of Clara, Hedvig and Davida? Well, between the ages of 20-22, they moved from their family homes in Tutaryd to the far-flung towns of  Hesslunda and  Mörarp. Their younger sister Davida followed suit on August 10, 1883 and moved to the Big City of Halmstad. The census for this town spans thousands of pages and is a daunting challenge to study. Perhaps Davida will turn up somewhere among them, but it will be a long while before I muster up the courage to dive into THAT archive.

Or perhaps like so many other ancestors, Davida Juhlin’s story will remain the silent gold of history!

Check back here on Wednesday, March 8 for a new blog!

Martian Swamp Gas?

Thanks to more than a decade of robotic studies, the surface of Mars is becoming a place as familiar to some of us as similar garden spots on Earth such as the Atacama Desert in Chile, or Devon Island in Canada. But this rust-colored world still has some tricks up its sleave!

Back in 2003, NASA astronomer Michael Mumma and his team discovered traces of methane in the dilute atmosphere of Mars. The gas was localized to only a few geographic areas in the equatorial zone in the martian Northern Hemisphere, but this was enough to get astrobiologists excited about the prospects for sub-surface life. The amount being released in a seasonal pattern was about 20,000 tons during the local summer months.


The discovery using ground-based telescopes in 2003 was soon confirmed a year later by other astronomers and by the Mars Express Orbiter, but the amount is highly variable. Ten years later, the Curiosity rover also detected methane in the atmosphere from its location many hundreds of miles from the nearest ‘plume’ locations. It became clear that the hit-or-miss nature of these detections had to do with the source of the methane turning on and off over time, and it was not some steady seepage going on all the time. Why was this happening, and did it have anything to do with living systems?

On Earth, there are organisms that take water (H2O) and combine it with carbon dioxide in the air (CO2) to create methane (CH3) as a by-product, but there are also inorganic processes that create methane too. For instance, electrostatic discharges can ionize water and carbon dioxide and can produce trillions of methane molecules per discharge. There is plenty of atmospheric dust in the very dry Martian atmosphere, so this is not a bad explanation at all.

This diagram shows possible ways that methane might make it into Mars’ atmosphere (sources) and disappear from the atmosphere (sinks). (Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan)

Still, the search for conclusive evidence for methane production and removal is one of the high frontiers in Martian research these days. New mechanisms are being proposed every year that involve living or inorganic origins. There is even some speculation that the Curiosity rover’s chemical lab was responsible for the rover’s methane ‘discovery’. Time will tell if some or any of these ideas ultimately checks out. There seem to be far more geological ways to create a bit of methane compared to biotic mechanisms. This means the odds do not look so good that the fleeting traces of methane we do see are produced by living organisms.

What does remain very exciting is that Mars is a chemically active place that has more than inorganic molecules in play. In 2014, the Curiosity rover took samples of mudstone and tested them with its on-board spectrometer. The samples were rich in organic molecules that have chlorine atoms including chlorobenzene (C6H4Cl2) , dichloroethane (C2H4Cl2), dichloropropane (C3H6Cl2) and dichlorobutane (C4H8Cl2). Chlorobenzene is not a naturally occurring compound on Earth. It is used in the manufacturing process for pesticides, adhesives, paints and rubber. Dichloropropane is used as an industrial solvent to make paint strippers, varnishes and furniture finish removers, and is classified as a carcinogen. There is even some speculation that the abundant perchlorate molecules (ClO4) in the Martian soil, when heated inside the spectrometer with the mudstone samples, created these new organics.

Mars is a frustratingly interesting place to study because, emotionally, it holds out hope for ultimately finding something exciting that takes us nearer to the idea that life once flourished there, or may still be present below its inaccessible surface. But all we have access to for now is its surface geology and atmosphere. From this we seem to encounter traces of exotic chemistry and perhaps our own contaminants at a handful of parts-per-billion. At these levels, the boring chemistry of Mars comes alive in the statistical noise of our measurements, and our dreams of Martian life are temporarily re-ignited.

Meanwhile, we will not rest until we have given Mars a better shot at revealing traces of its biosphere either ancient or contemporary!

Check back here on Thursday, March 2 for the next essay!

Near Death Experiences

A CBS News Survey in 2014  found that 3 in 4 Americans believe in an afterlife. A similar survey in the UK in 2009 found 1 in 2 believe in life after death and 70% believe in the existence of a human soul.

So pervasive is this belief that, amazingly, more Britons believe in life after death than believe in God! This belief in life-after-death is so fundamental to how humans see the world that a 2013 Pew Poll of Americans  found that 13% of athiests also believed in an afterlife!

Luigi Schiavonetti’s 1808 engraving of a soul leaving a body. (Credit: National Gallery of Victoria, Melbourne)

Of course, many will argue that once you are gone you are gone, but in that twilight moment in the minutes and seconds before death, people have been revived through heroic medical interventions and some but not all declare they have experienced ‘something’ absolutely remarkable.

Called Near Death Experiences, entire shelves of books have been written on this subject over the decades since the ground-breaking work of Ceila Green in 1968 and then popularized in 1975 by psychiatrist Raymond Moody. Extensive eye-witness accounts were recorded, classified and sorted into a small number of apparently archetypical scenarios such as tunnels of pure light; out of body experiences; meeting loved ones; indescribable love. According to a Gallup Poll about 3% of Americans claim to have had them.  There were early attempts by Duncan MacDougall in 1901 at detecting the exit of the soul from the body by carefully weighing the patient, but all failed, and were immediately explained by denying that the soul had any weight at all.

Scientists have largely refused to wade into this area of inquiry because, like many other human beliefs, there is enormous public resistance to scientists meddling in such cherished and highly personal ideas shared by virtually all humans, even some athiests! In a classic case of what psychologists call confirmation bias, there is nothing that science can say about this matter that would be trusted unless it lines up exactly to confirm what we have all made up our minds about, literally for millennia. That said, I myself, must tread very carefully as I write this blog because, frankly, those of you reading it have also made up your mind about the subject and I do not want to slap you in the face by disrespecting your fundamental core beliefs, which will always trump anything a scientist can tell you. Even my simple uttering of this disclaimer will be interpreted as me being a condescending scientist…or worse!

But I cannot help myself! I have been curious about this subject all my life, and any new insights I come across in my readings are like candy to my brain. So here goes!

NDEs are not a feature of any other organ than the brain because they involve visual perceptions, bodily sensations, and the knitting together of a story that is later told by the ‘traveler’. All of these are brain functions, so it is no wonder that those who study the clinical aspects of NDEs begin with what the brain is doing. Amazingly, you do not even have to be clinically ‘near death’ to experience them. All that is required is a deep conviction that you ARE dying to trigger them.

What could be a more compelling and simple idea than putting a dying person in a functional magnetic resonance imager (fMRI) or strapping an EEG net to their heads, and literally watching what the brain is doing during one of these events? Well, it would be a heinous experiment and an unwelcomed intrusion on a patient’s privacy, but nevertheless these things do happen accidentally. Cardiac patients who are more likely to die suddenly and be recovered are often monitored for other reasons prior to their NDE, and there are many other indirect ways to snoop on the brain to see what happens too.

We have already learned from fMRI studies that there is a specific brain region that allows you to have a sense of where your body is located in space. In an earlier blog I discussed how removing the stimulation of this normally very active region causes meditators to have the sensation of being ‘at-one’ with the universe. This state can also be reproduced at will through chemical manipulation. The region, when stimulated with an electrode, or during temporal lobe epilepsy, also produces the aura sensation that your Self is no longer anchored to your body in space during so-called Out-of-Body (OBE) events. So, an essential element of your body sense during an NDE can be traced to one specific brain region and whether it’s activity is stimulated or depressed. This region wins both ways because when its electrical activity is gone, you have one ‘cosmic’ sensation of leaving your body, and when it is over-stimulated you have the OBE sensation. As we know, death is the ultimate event that lowers brain activity, or temporarily elevates it in other places as blood flow catastrophically changes. We all have the same brains, so the real question is, why is it that EVERYONE doesn’t have a NDE?

It all seems to depend on how close you get to the precipice of never returning from the journey, and it is the closeness of your brain to this physiological edge that seems to trigger the events leading to this NDE experience. But we do not know for certain.

A 2011 Scientific American article summarized some of these elements announced by brain researchers Dean Mobbs and Caroline Watt.

OBE experiences can be artificially triggered by stimulating the right temporoparietal junction in the brain. Patients with Cotard or “walking corpse” syndrome believe they are dead. This is a condition caused by trauma to the parietal cortex and the prefrontal cortex. Parkinson’s disease patients have reported visions of ghosts. This condition involves abnormal functioning of dopamine, a neurotransmitter that can sometimes but not all the time evoke hallucinations. The common experience of reliving moments from one’s life can be tied to a neural circuit involving the locus coeruleus, which releases noradrenaline during stress and trauma. The locus coeruleus (shown below) is connected to brain regions that are involved with emotion and memory, such as the amygdala and hypothalamus. Finally, a number of medicinal and recreational drugs can mirror the euphoria often felt during NDEs, such as the anesthetic ketamine, which can trigger out-of-body experiences and hallucinations. These discussions of the neural basis for many of the separate elements to NBEs are now part of the official medical explanation in places such as the one found in Tim Newman’s 2016 article in Medical News Today.

Norepinephrine system (Credit: Patricia Brown, University of Cincinnati)

Beware, however, of other articles like the one in The Atlantic called ‘The Science of Near Death Experiences’. This 2015 popularization, written in the typical breezy style of newspaper reporters, also purported to summarize what we know about this condition. Sadly, the reporter spent most of the article interviewing those who experienced it and hardly any column space on actual scientific research. It was a typical ‘puff piece’ that offered nothing more than speculation and very self-serving and bias-affirming pseudoscience, along-side free plugs for many recent, lurid, books and movies about first-person accounts.

The bottom line is that NDEs are by no means common to people who think they are dying, and their incidence crosses many religious boundaries. They remain enormously powerful events that actually change the lives and even personalities of the survivors, and so they are not merely will-o-the-whisp hallucinations. We do know that their detailed descriptions follow specific cultural expectations for what the afterlife is like: a New Guinee tribesman will not describe the event the same way as a southern Evangelical.

We are only beginning to understand how our brains synthesize what we experience into the on-going story that is our personal reality, but we know from the evidence of numerous brain pathologies that this is a highly plastic process in which imagination and emotion blend with hard facts in a sometimes inseparable tapestry. Our senses are objectively known to be fallible in countless ways if left unattended, and how we interpret what we experiences is as much a logical process as a process of out-right confabulation. Like many other events in our lives, NDEs are seen as one experience that our brains work very hard to incorporate into a plausible story of our world. It is this story that through millions of years of evolution allows us to function as an integrated Self,  avoid being injured or eaten, and  propagate our genes to the next generation.

Isn’t it amazing that, against this backdrop of cognitive dissonance, sensory bias, emotional chaos, and evolutionary hard-wiring  we can create a workable story of who we are in the first place?

Check back here on Monday February 28 for my next blog!

Death By Vacuum

As an astrophysicist, this has GOT to be one of my favorite ‘fringe’ topics in physics. There’s a long preamble story behind it, though!

The discovery of the Higgs Boson with a mass of 126 GeV, about 130 times more massive than a proton, was an exciting event back in 2012. By that time we had a reasonably complete Standard Model of how particles and fields operated in Nature to create everything from a uranium atom and a rainbow, to lighting the interior of our sun. A key ingredient was a brand new fundamental field in nature, and its associated particle called the Higgs boson. The Standard Model says that all fundamental particles in Nature have absolutely no mass, but they all interact with the Higgs field. Depending on how strong this interaction, like swimming through a container of molasses, they gain different amounts of mass. But the existence of this Higgs field has led to some deep concerns about our world that go well beyond how this particle creates the physical property we call mass.

In a nutshell, according to the Standard Model, all particles interact with the ever-present Higgs field, which permeates all space. For example, the W-particles interact very strongly with the Higgs field and gain the most mass, while photons interact not at all, remain massless.

The Higgs particles come from the Higgs field, which as I said is present in every cubic centimeter of space in our universe. That’s why electrons in the farthest galaxy have the same mass as those here on Earth. But Higgs particles can also interact with each other. This produces a very interesting effect, like the tension in a stretched spring. A cubic centimeter of space anywhere in the universe is not at all perfectly empty, and actually has a potential energy ‘stress’ associated with it. This potential energy is  related to just how massive the Higgs boson is. You can draw a curve like the one below that shows the vacuum energy  and how it changes with the Higgs particle mass:

Now the Higgs mass actually changes as the universe expands and cools. When the universe was very hot, the curve looked like the one on the right, and the mass of the Higgs was zero at the bottom of the curve. As the universe expanded and cooled, this Higgs interaction curve turned into the one on the left, which shows that the mass of the Higgs is now X0 or 126 GeV. Note, the Higgs mass represented by the red ball used to be zero, but ‘rolled down’ into the lower-energy pit as the universe cooled.

The Higgs energy curve shows a very stable situation for ‘empty’ space at its lowest energy (green balls) because there is a big energy wall between where the field is today, and where it used to be (red ball). That means that if you pumped a bit of energy into empty space by colliding two particles there, it would not suddenly turn space into the roaring hot house of the Higgs field at the top of this curve.

We don’t actually know exactly what the Higgs curve looks like, but physicists have been able to make models of many alternative versions of the above curve to test out how stable the vacuum is. What they  found is something very interesting.

The many different kinds of Higgs vacuua can be defined  by using two masses: the Higgs mass and the mass of the top quark. Mathematically, you can then vary the values for the Higgs boson and the Top quark and see what happens to the stability of the vacuum. The results are summarized in the plot below.

The big surprise is that, from the observed mass of the Higgs boson and our top quark shown in the small box, their values are consistent with our space being inside a very narrow zone of what is called meta-stability. We do not seem to be living in a universe where we can expect space to be perfectly stable. What does THAT mean? It does sound rather ominous that empty space can be unstable!

What it means is that, at least in principle, if you collided particles with enough energy that they literally blow-torched a small region of space, this could change the Higgs mass enough that the results could be catastrophic. Even though the collision region is smaller than an atom, once created, it could expand at the speed of light like an inflating bubble. The interior would be a region of space with new physics, and new masses for all of the fundamental particles and forces. The surface of this bubble would be a maelstrom of high-energy collisions leaking out of empty space! You wouldn’t see the wall of this bubble coming. The walls can contain a huge amount of energy, so you would be incinerated as the bubble wall ploughed through you.

Of course the world is not that simple. These are all calculations based on the Standard Model, which may be incomplete. Also, we know that cosmic rays collide with Earth’s atmosphere at energies far beyond anything we will ever achieve…and we are still here.

So sit back and relax and try not to worry too much about Death By Vacuum.

Then again…

 

Return here on Wednesday, February 22 for my next blog!