Qs people asked me on science and my replies to them - part 149

Q: Is it true that plastic water bottles can cause fire in a car?

Krishna: Yes,  on a hot, summer day, the plastic can act as a lense, focusing light into a high-energy beam that's intense enough to burn material like car-seat upholstery.

Q: Why do we think some faces are  ugly and some beautiful? What is the science behind it?

Krishna: Scientists think it is because of  symmetry. Faces that we deem attractive tend to be symmetrical. Attractive faces also are average.

In a symmetrical face, the left and right sides look like each other. They’re not perfect mirror images. But our eyes read faces with similar proportions on both sides as symmetrical.

People’s faces usually only differ subtly in symmetry. Everyone's face is slightly asymmetrical, but in different ways. In the end, many of these faces seem symmetrical. So symmetry looks normal to us. And we then like it. 

This averageness refers to how similar a face looks to most other faces in a population. Average, here, does not mean “so-so.” Rather, average faces are a mathematical average (or mean) of most people’s features. And, in general, people find such faces quite attractive.

Averageness includes all kinds of factors. Such as the size of the features of your face and their arrangement. For example, the distance between the centers of a woman’s eyes affects whether she is considered beautiful. People find her most attractive when that distance is just under half of the width of the face. Average faces are more attractive because they seem more familiar.

Research shows that people with more symmetrical faces don’t just look nice. They also tend to be healthier than asymmetrical people. Genes provide the instructions for how a cell is to perform. All people have the same number of genes. But people with more average faces tend to have a greater diversity in the genes they are born with. And that, research has shown, can lead to a stronger immune system and better health.

Several other factors too make men think why a woman is beautiful. The hormones a woman produces during reproductive age,  the glow of her skin. Estrogen and testosterone play important roles in finding something attractive. They denote fertility, youth, muscle build-up  and maturity.

Then cultural differences and conditioning of minds too make some faces look attractive to some people and other ugly.

Attractive, healthy faces turn on reward and pleasure centers of our brains so that we can actually experience beauty and fall in love with it. Our brains connect beauty with goodness too.

Research on birds also shows that female birds prefer good-looking guys. For example, among satin bowerbirds, females prefer males whose feathers reflect more ultraviolet (UV) light. Researchers at Auburn University in Alabama caught male bowerbirds and took blood samples. Males with blood parasites had feathers reflecting less UV light than healthy males. So when females chose males with UV-rich plumage, they weren’t just being shallow. They were using that information to find healthy males to father their young.

Healthier peacocks have more eyespots in their tails. These birds also splay their flashy tails more frequently to the females. Females get attracted to healthy things and avoid sick males as they cannot father their healthy offspring! It is important for the very survival of the group!

Simple, pretty faces simply are easier on our brains than complicated and ugly ones and that is why we get attracted to and choose them

Q: Why do clouds glow during night sometimes?

Krishna: Because of meteors, and climate change to some extent. Meteors leave a trail of dust that create the noctilucent (Nok-tih-LU-sint) cloud. The cloud’s name comes from Latin words for “night-lit.”

Smoke from the burning space rock “seed” Earth’s upper atmosphere with dust. Water vapour can condense around those dust bits to form clouds. Meteors burn up high in the atmosphere. So these noctilucent clouds also form high up.

Given the curvature of the Earth, objects high in the sky can still catch some sunlight well after the sun sets closer to the ground. Noctilucent clouds’ extreme height is what keeps them shining in the dark. And they appear blue because all of the other wavelengths of light have scattered.

Noctilucent clouds typically emerge at high latitudes, meaning near or over the poles. 

Although space rocks commonly enter Earth’s atmosphere, they seldom spawn clouds. The reason: Those rocks tend to break apart too high. The mesosphere, where the breakups typically happen, is some 81 kilometers (50 miles) above the ground. It hosts very little water.

But that could change. More water is entering the upper atmosphere as Earth’s climate warms. 

For a noctilucent cloud to form, the mesosphere must be super cold — below –40° Celsius (–40° Fahrenheit). These temps develop above Earth’s poles in the summer. Near the Arctic, that means peak noctilucent season is June through August. Peak season near Antarctica is December through February. 

At those low temperatures, the air is dry. And at such high altitudes, the air is also relatively dust-free. Without some dust particle to glom onto, any moisture here tends not to freeze; it is “supercooled.” 

But that can change with the arrival of meteor smoke. With something to freeze onto, the supercooled droplets rapidly turn to ice. Once one ice crystal forms, more join it in what becomes a chain reaction. If the process is large enough, a noctilucent cloud develops.

About 3 percent of each ice crystal in a noctilucent cloud comes from meteors. 

Today, noctilucent clouds seldom develop outside the Arctic and Antarctic. But that might not be true for long. Indeed, these clouds have already begun to creep down into the regions between the poles and the tropics. One reason seems to be the increasing presence of methane at high altitudes.

High up in the mesosphere, methane takes part in a complex chemical reaction that forms new molecules of water. Water vapor can increase if methane increases. According to experts in climate science, noctilucent clouds outside of polar skies as a potential symptom of climate change. 

Methane, a potent greenhouse gas, can be released into the sky by thawing permafrost, burping cows, biomass burning and more. Increasing methane levels may boost the amount of water in the mesosphere. In turn, that could improve chances for noctilucent clouds.

Rising levels of another greenhouse gas, carbon dioxide, may also play a role. As CO₂boosts air temperatures near the ground, it can cause temps in the mesosphere to drop. That cooling effect could help supercool more water — a key ingredient for noctilucent clouds.

In step with rising greenhouse gases, the breadth and frequency of glowing clouds have increased over the last few decades, climate research hints. These clouds also ventured toward Earth’s equator, beyond their normal territory. And increased methane played a key role in the clouds’ spread, according to  reports published  in 2001 in Advances in Space Research (1). 

Glowing clouds are not only spreading farther across the sky. Since 1998, they have also been appearing more often and getting brighter (2). A team of German researchers reported those findings in a 2015 study.

Q: How will you explain the universal human behaviour of seeking or expecting dramatic mysteries (either supernatural or scientific) behind all unknown facts? While several unknown of past are trivial today. Why this craving for mystery? 

Q: Can ghosts write?

Krishna: :) If you can imagine something, you can as well imagine several things about it. There is no evidence of ghosts, according to science. Now if you imagine ghosts, also imagine they can write! And imagine they can write poetry, stories, can create art, sing songs, play games, win medals and run for President. Who can stop your wild imagination?

Science and the paranormal

Q: How do paranormal investigators remove the negative entity from a haunted house?

References:

1. https://www.sciencedirect.com/science/article/pii/S0273117701800211...

2. https://www.researchgate.net/publication/307874917_Long-term_variat...