The Science of Spice

I watched the man at the table next to me begin to sweat profusely. I was enjoying wings with my family, and he had clearly chosen one of the spicier sauces. Why was he doing this to himself?  

According to the US Department of Agriculture, the average American eats over 7 pounds of chilies a year. What is it that attracts people, like the man in the wings restaurant, to the burn of eating chilies? It is possible that you feel the same reaction eating chilies that you do riding a roller coaster? Yes, it is surprisingly similar! You get the same sense of anticipation, heart beat increase, then a rush of adrenaline and endorphins.  

It has to do with the receptors that send signals to your brain, telling you that you are eating something hot. Your papillae, located on the tongue, are the receptors that detect spice, but these receptors also are activated by thermal stimuli. When you eat a chile pepper, your brain thinks your tongue is literally on fire, hence the sweating that ensues. With enough heat, your body begins to produce adrenaline and your heart pumps faster. Then, to help block the pain, your body produces endorphins. Just like riding a roller coaster, this is what makes peppers so exciting to consume.

Many people enjoy the effects of spice, but why do some people max out with the mildest jalapeno, while others enjoy much hotter peppers? There is no solid research yet to indicate that genetic differences could play a role in our tolerance to spice. However, there is plenty of data suggesting that the receptors on our tongues lose sensitivity under prolonged exposure to the same stimulus. So the more spice our capsaicin receptors are exposed to over time, the less we feel the burn. Meaning, if I had eaten a diet rich in spicy food as a child, I would be less sensitive to the burn today.

Scoville Heat Units (SHU) measure the spiciness of peppers. Photo credit: Flickr

Capsaicin (pronounced cap-SAY-iss-in), the chemical compound produced by the chile that gives them their heat, can be detected by human taste buds in solutions of ten parts per million. The spice of a chile is measured in Scoville Heat Units (SHU). Wilbur Scoville, a chemist at Parke-Davis Pharmaceutical Company in Detroit, developed the SHU scale in 1912 by diluting chile pepper extract in sugar water. A panel of tasters would then rate the spice in the dilutions until the burn was no longer detectable. Today, we no longer rely on a panel of human tasters to determine SHU, but instead we can use high-pressure liquid chromatography, a computerized method that can determine the capsaicin concentration very precisely. This method is still not perfect though, as it may ignore other chemicals that are enhancing how spicy we perceive the pepper. Today, Chile peppers range in heat from 0 SHU (bell pepper) to over 1,000,000 SHU (Bhut Jolokia pepper).  A typical jalapeno ranges between 2,500-5,000 SHU.

Capsaicin, what gives peppers their heat, is made in the glands under the stem and held in the placenta, the lighter color rib, which is down the inside of the pepper.


When making dishes with chile peppers, do you carefully discard the seeds thinking you are avoiding the spice? If so, you have been woefully misguided. The capsaicin is not in the seeds, but is actually produced in the capsaicin glands, which are in the bulb right underneath the stem and stored in the chile’s placenta, the lighter colored rib running down the inside of the pepper.  The seeds can occasionally absorb some of the heat because of their proximity to the area where the capsaicin is produced, but they are not the spicy part of the pepper.

Humans have conserved the capsaicin receptors presumably to warn us that whatever we’ve put in our mouths is bad news. However, capsaicin and other hot foods won’t damage your tongue – so eat as much as you want and enjoy the burn!

Peer edited by Mikayla Armstrong.

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Is Your Impostor Syndrome Showing?

Image by Kelsey BreretonI was sitting at my kitchen table with a scattered mess of textbooks and notes studying for my first graduate school final.  The white board was filled with incoherent scribbles of chemical structures and electron arrows.  I had hit a wall, and all the thoughts of self doubt and inadequacy played on an endless loop through my brain: “I’m not as smart as everyone else, I don’t deserve to be here, and now they will really know I’m a fraud.”  I ended up passing the courses, so clearly I am smart enough to be at UNC. However, those negative feelings kept creeping back up to the surface over the years, no matter how many P’s I earned in my courses, positive reviews I received from my PI, or even fellowship awards I won.  The nagging feeling of inadequacy remained!  It turns out this emotion has a name: impostor phenomenon, aka impostor syndrome.

Impostor syndrome is described as feelings of perceived inadequacy even when there is plenty of evidence otherwise.  Many people struggle silently with feelings of chronic self-doubt, intellectual fraudulence, anxiety, and depression.  These can become so severe that it stifles performance in graduate school or the workplace.  Ironically, it’s usually successful people that suffer from impostor syndrome; even acclaimed celebrities and high profile business executives are not immune. They will attribute their success to luck or generosity of others – anything but their own hard work and skills. This is extremely common for many professionals and graduate students. These high achievers set unsustainable, high expectations on their work and when the standards are not met, allowing feelings of deficiency to creep in.

The impostor phenomenon was first studied by Suzanne Imes and Dr. Pauline Clance, who  saw a strong link between the impostor syndrome and perfectionism. Imes posits that impostor syndrome could result from growing up in households that place an exuberant emphasis on achievement.  This resonates with my personal experience. In my family, we got A’s. Not A-’s. Only A’s were acceptable, and before long, I became overtly self-critical when I didn’t get an A on a test or even a homework assignment.  It’s no wonder why self-worth becomes directly tied to achievement.  Students either fear their work won’t be perfect and procrastinate, or they develop obsessive work habits, spending more energy than necessary.  These unhealthy study habits, developed in high school, can become firmly seeded during undergraduate careers.  In intensive graduate programs, that sense of achievement, once drawn from grades, gets drawn from the success of research projects.

Graduate and professional students spend years struggling to learn extremely difficult material, overcoming failed experiments, and (hopefully) becoming experts in highly specialized fields.  It is easy for students to lose their sense of personal identity as they become expert scientists. Perfectionism and attention to detail are described as skills by many successful scientists, but these skills can also be holding us back in many ways if we succumb to the Impostor Monster.

Do others see your impostor syndrome?

Most of the time, the people suffering from impostor syndrome hide their symptoms extremely well because they are afraid of being exposed as a fraud.  If impostor syndrome becomes too bad, others will start to notice your lack of self-confidence and increased self-doubt.  This can be problematic during performance evaluations, job interviews, and committee meetings and can start to negatively impact your life other than just emotionally.

How could your impostor syndrome be holding you back?

Impacts on graduate school:

  1. The fear of being exposed as a fraud can lead students to take less risks in lab.  Students would be afraid of an experiment failing and having to tell their boss they failed, over time leading to less creative research and lower productivity.
  2. Holding back on submitting publications or proposals because they might not be absolutely perfect.
  3. Negative self talk can lead you to think you’re not good enough, then you don’t do your best work which, by default, reinforcing the negative thoughts.  
  4. Constantly comparing yourself to others only feeds the impostor monster and wastes energy that could be better spent elsewhere.

Impacts on professional career:

  1. Not taking ownership of personal accomplishments can result in not getting a promotions, awards, and recognition.
  2. Miss opportunities for new experiences: lowering career goals to match feelings of being unqualified. For example, deciding not to pursue a tenure-track position at a research intensive university because of the feelings of fraudulence and inadequacy.
  3. Work way too hard to make up for your “deficiencies” which can make you more likely to burn out.

So what can we do about this impostor syndrome?

Most people struggle with this their whole lives, but there are ways to keep it from running the show.  

Put your impostor syndrome in perspective: Identify your feelings and do a reality check.  Assess whether your feelings of incompetence are exaggerated.

Remind yourself what you are good at: Determine what your skills are and what you have accomplished so far.  Remember, getting into graduate school itself is a major accomplishment!

Write down the compliments that you receive: On days when you’re struggling with negative thoughts, reading the positive thoughts others have about you will boost your self-confidence. Also, try to accept compliments with a simple “thank you” rather than discounting them.

Build a support group of trusted friends and family: There’s a good chance that most of your peers are going through this too and think that they are also the only one suffering.  

It’s been a few years now since my first graduate school finals, but my impostor syndrome still resurfaces from time to time. I still struggle everyday with setting realistic standards for the amount of work I can accomplish and avoid my excessive perfectionist tendencies. When I start to think “I’m not good enough,” I stop and remind myself what I’m good at and how much I have improved as a scientist since starting graduate school. Don’t let your impostor syndrome run wild and limit your future success in life.

Peer edited by Tom Gilliss and Kelsey Noll. 

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Why it Takes Tanks to Separate Two Phone Books

It can be tempting in science, and in life, to believe that every stone has already been turned, that the most impactful steps in your field have already been made, that there is nothing left for you to discover. This type of sentiment is often said to have existed (though it was certainly not ubiquitous) in late nineteenth century physics, when people may have felt there was nothing more to be done but the refinement of previous measurements. Of course, the turn of the century shattered any such mindset with the revolutions of quantum mechanics and general relativity.

Even if science does have a good handle on a certain regime of natural behavior, solid work still remains to be done. Even in the most well-trodden fields, there are stones that can be found yet unturned.

A great example of a surprising phenomenon arising from basic rules is that of the phone book trick, which goes something like this: Place two phone books so that they open toward each other and overlap alternating pages from the two books. Now attempt to pull the books apart by their spines. You can’t! In short, it is extremely difficult to pull apart two phone books whose pages have been interleaved. Discovery Channel’s MythBusters gave it a shot and could not pull apart the phone books until they employed the help of a few military tanks.

As it turns out, though squarely in the domain of classical physics, the phone book phenomenon had not been studied in great detail until recently when a few valiant physicists, with resolve to leave no well-trodden scientific stone unturned, sought to dig deeper and give the ol’ phone book trick a proper treatment.

A few surprising results arose from examination of this seemingly simple system, and we’ll discuss one of them here. As you may have guessed, friction is the source of the two phone books’ incredible resistance to separation. But how does that friction arise? Friction is due to a “normal force,” meaning that the direction in which friction acts is perpendicular to the force that initially causes there to be contact between two objects. Just imagine pressing your hand down on a table: You press down, but the resulting friction prevents your hand from moving left or right.

If friction is caused by a perpendicular force than how does friction arise in the phone book trick? After all, you’re pulling on the spines of the books and friction directly opposes your pull — there are no perpendicular, 90˚ forces there, right?

Reproduced from Dalnoki-Veress, Salez, &amp; Restagno. "Why can't you separate interleaved books?" <em>Physics Today</em>, June 2016, 74, with the permission of the American Institute of Physics.

A diagram showing how pages angle outward from a book’s spine when they are interleaved with the pages of another book. Someone attempting to separate the two books would pull on the spine in the direction of T. Reproduced from Dalnoki-Veress, Salez, & Restagno. “Why can’t you separate interleaved books?” Physics Today, June 2016, 74, with the permission of the American Institute of Physics.

The secret lies in the fanning out of the interleaved pages as they leave the spines of the books. Because the pages are overlapped with those of the other book, they leave their spine at a small angle. Pulling on the spine then pulls on an angled page, like pulling on a rope, and, because of the small angle, that page gets in part pulled downward. This downward action squeezes a page downward, not side-to-side, on top of a neighboring page from the other book and our mysterious side-to-side friction force appears. Now repeat this process for as many pages as are in a phone book, and you’ve got a lot of friction!

Though a familiar concept, friction is a subject worthy of much more scientific study and the physicists behind this phone book trick have taken the time to point out some of the ongoing research on friction in modern science. Check out their full Physical Review Letters publication for more detail.

Peer edited by Joanna Warren.

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The Impossibly Ideal Scientist

Image and artwork created by Lindsay Walton

The solving scientist: can this be fixed in time?

Beverly Crusher. Roy Hinkley. Emmett Brown. Samantha Carter. Sheldon Cooper. The Doctor. Abby Sciuto. Temperance Brennan. What do each of these scientists have in common? From creating a Geiger counter out of bamboo, to discovering, identifying, and curing a disease in the nick of time, each of these cinematic scientists has completed impossible tasks. Often works of fiction create all-knowing scientists who can solve any problem posed to them in the nick of time. However, do these depictions affect public expectations and imply that scientists are experts in every scientific field imaginable?

During recent years, many stereotypes about scientists have shifted, allowing researchers to shed the traditional “geeky” scientist persona. Some say that new perceptions of scientists reflect their cinematic portrayal as heroes and experts, “mavericks” who overcome obstacles both cerebral and physical in nature, persevering until they successfully save the day at the last moment possible.

However, how do these changing ideas about scientists translate to public expectations of the average scientist? Do “maverick” scientists portrayed in film cause people to idealize scientists and lead to the expectation that they will have all the knowledge Data, the android in Star Trek, has in his memory banks? In a recent survey, 49% of polled scientists stated that they felt the public has unrealistic expectations about the speed at which scientists should generate solutions to problems. Perhaps scientists feel the pressure of comparing themselves to their science fiction counterparts. The data certainly shows that the public has historically had high expectations for scientists. When polled, most Americans predicted scientists would cure cancer within 50 years, with polling starting as early as 1949. However, cancer still has not been cured, as exhibited by the recent National Cancer Moonshot proposal generated by President Obama, pushing for research funding to improve cancer patient outcomes.

Is it even possible to be the all-knowing scientist? As a lowly graduate student, I know that I will never be as brilliant as Dr. Beverly Crusher, who could probably cure cancer within one single episode. However, I believe that each of these idealized scientists creates a good model of what we should hope to be as scientists — individuals who thrive on the work, constantly learn new things, contribute to current knowledge, and reward the faith and trust that the public places in them.

Peer edited by Kaylee Helfrich. Image by Lindsay Walton.

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What Will A Trump Presidency Mean for Scientists? votes are in, and to the surprise of pundits and pollsters everywhere, Donald J. Trump has been elected the 45th president of the United States. However, many scientists are concerned about what a Trump presidency would mean for important issues like climate change and research funding. For one, Trump is cautious about allocating resources for scientific research (see this pre-election article from Science and Q&A session at for more). On the other hand, Trump has also stressed the importance of continuing research relevant for public health, such as Alzheimer’s disease. Due to his unclear stance on research funding, it is difficult to predict whether Trump will propose more budget cuts to the NIH and NSF.

More alarming, however, is Trump’s consistent denial of climate change. He has repeatedly called climate change a hoax and has strongly endorsed the US pulling out of the Paris climate agreement. On November 2nd, less than a week before the election, the Bloomberg BNA reported that Trump, at a Michigan rally, proposed to end climate spending.

“We’re going to put America first. That includes canceling billions in climate change spending for the United Nations, a number Hillary wants to increase, and instead use that money to provide for American infrastructure including clean water, clean air and safety,” said Trump.

One example of infrastructure Trump wants to expand in his first 100 days in office is the Keystone XL pipeline, which would provide a more direct transportation of oil from Canada into the US compared to the current Keystone pipeline. Although Trump has not yet met with TransCanada specifically, Trump has consistently pushed for removing environmental regulations. Perhaps in a significant conflict of interest, he also owns stock in Energy Transfer Partners, the company responsible for building the pipeline. President Obama and Hillary Clinton had opposed the pipeline because they did not believe building the pipeline would have a significant impact on the economy, creating jobs, or lowering petrol prices. In addition, environmental activists worry that this deal with TransCanada Corp. could instead increase America’s reliance on carbon fuel.

Nevertheless, Trump’s stance on many key issues in science and technology are still unclear. Ars Technica expresses concerns about his unclear stance on net neutrality and encryption (Trump’s campaign statement for cybersecurity can be found here). Trump’s senior advisors have suggested that even NASA could change focus under his direction. Based on his business background, backed by a Republican-majority Congress, it’s possible that Trump will place his efforts in science and technology as they relate to job creation and deregulation.

At this point, there’s still much that is unknown on how Trump will impact science policy. For more info, check out this Nature news article summarizing the concerns of other scientists.

Peer edited by Aminah Wali.

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Cold, What Is It Good For? is officially still three weeks away, although the alternating 30° F nights and 75° F days makes that difficult to remember. The arrival of winter means that it is less pleasant to be outside, there are fewer hours of sunlight, and it is harder to get out of bed in the morning. Most Southerners don’t really enjoy the winter. But here are three ways really cold temperatures actually help physicists in their quest to understand nature.


Some telescopes must go to the extreme cold in Antarctica. The South Pole Telescope is recording some of the first light from the universe. This light, called the Cosmic Microwave Background, contains clues to help astronomers understand what makes up the Universe and how that has changed over time. The high altitude and low temperatures in Antarctica make it possible to see these radio waves, as there is less water vapor present in the atmosphere to absorb them when compared to other regions. For a fascinating account of what it is like to work with the South Pole Telescope, check out Keith’s blog from his time there.

For most observatories, the best observing conditions occur during the winter. This is primarily because the air is less turbulent. Heat from the earth rises up at night during the summer months, creating a more turbulent atmosphere. This causes stars to appear more blurry. But during the winter, the ground is cooler, so there is less turbulence at night. However, most observatories experience more extreme weather during the winter, somewhat limiting how often astronomers can utilize the best conditions.

The colder weather is a great reason to go to a star party over the next few months. For people living in the Triangle, the Morehead Planetarium teams up with the Chapel Hill Astronomical and Observational Society to stargaze about once a month at Jordan Lake. You can see the full schedule here.

Quantum Mechanics

When you think about how things move and interact, you are most likely pondering what physicists refer to as classical mechanics, the motion of relatively large things. But quantum mechanics deals with how tiny, individual atoms and particles move and interact with their environment. However, quantum mechanics is difficult to study because atoms move quickly at room temperature. When the temperature drops, though, atoms lose energy and slow down. This enables physicists to study some of the strange quantum mechanical properties of atoms. For example, at temperatures around -459° F, individual atoms can gather together and begin acting collectively like a single atom. At the coldest possible temperature, known as absolute zero (-459.6° F), atoms lose all their energy and stop moving. This phenomenon of particles acting as a group only occurs close to absolute zero, forming a state of matter known as a Bose-Einstein condensate. First created in a laboratory in 1995 and winning the Physics Nobel Prize in 2001, Bose-Einstein condensates help physicists study some of the strange quantum mechanical properties of atoms and how they interact in extreme conditions.

The Large Hadron Collider

The Large Hadron Collider at CERN. Image credit: CERN

The Large Hadron Collider (LHC), a 16.7-mile long particle collider on the border of France and Switzerland, operates at -456° F, slightly warmer than the temperature required for Bose-Einstein condensates. Before colliding, particles can travel around the ring thousands of times. To keep particles along the track before colliding, the LHC uses strong magnetic fields generated by superconducting materials. Electric current is required to make the magnetic fields, which often generates heat (think of how cell phones heat up during charging). Superconducting materials, instead, create very little heat when cooled down to very low temperatures, creating the right conditions for physicists to use them at the LHC. These conditions enable the LHC to investigate the building blocks of nature.

So the next time you are fretting over the cold, perhaps you can remember the physicists who need the cold to make discoveries happen.

Peer edited by Lindsay Walton and Manisit Das.

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