Why Do Insects Fly Towards Lights?

Episode Summary

Executive Summary: This CrowdScience episode is a Q&A roundtable with physicist Malcolm Fairburn, entomologist Erica McAllister, and plasma physicist Kate Lancaster. It covers whether gravity can change, why insects are drawn to light, how plasma TVs differ from fusion reactors, why mosquito bites itch, and what the Higgs boson does. The episode blends clear explanations, admitted scientific uncertainty, and practical caveats.

Main Topics: Can gravity ever change? (Priority: 5/5): Malcolm explains gravity as a universal force linked to mass and the gravitational constant. He says Earth’s gravity changes only negligibly with mass changes, and that no evidence shows big changes in Newton’s constant over 13.7 billion years, though some speculative theories allow it. Why insects are attracted to light (Priority: 5/5): Erica outlines competing theories: navigation by moonlight and confusion from nearby lamps, possible pheromone-related attraction, and UV/light-spectrum effects. She emphasizes that insect attraction to light is still not fully understood and needs more research funding. Plasma TVs versus fusion plasmas (Priority: 4/5): Kate Lancaster distinguishes cold plasmas in TVs from the truly hot, equilibrium plasmas required for fusion. She explains that plasma TVs use ionized gas to generate UV light, which phosphors convert to visible RGB display colors. Why mosquito bites itch (Priority: 5/5): Erica explains that itch is caused by the human immune response to mosquito saliva anticoagulants, not by the mosquito intentionally. Scratching worsens the reaction by triggering more inflammation and swelling. What the Higgs boson does (Priority: 5/5): Malcolm says the Higgs boson gives mass to particles like electrons and quarks, enabling atoms and chemistry. He argues it is foundational to understanding the universe, while practical applications may emerge only much later, as happened with quantum physics. Science communication and listener questions (Priority: 3/5): The episode uses listener-submitted questions from Uganda, Belfast/Sydney, Geneva, and Kampala to connect abstract physics and biology to everyday curiosity, while also highlighting ongoing uncertainty and the need for more research.

Key Arguments: Gravity is not just an Earth-pulling force; it acts between all masses in the universe, though most effects are tiny unless one body is very large. Earth’s mass can change slightly, but not enough to noticeably alter gravity for everyday life. Speculative frameworks like string theory could allow gravity’s strength to vary if extra dimensions changed size, but experiments show no evidence of such variation. Insect attraction to light remains unresolved; current explanations are incomplete and may depend on species, spectrum, and night-navigation behavior. Mosquito itch is an immune-side effect: saliva introduced during feeding triggers antibodies, histamines, and swelling in the host. Scratching mosquito bites makes them itchier because it intensifies inflammation and signals the body to send more immune activity to the area. Plasma TVs operate with cold plasmas producing UV light, while fusion reactors require extremely hot, equilibrium plasmas at hundreds of millions of degrees. The Higgs boson is central because it gives mass to fundamental particles, making atoms and therefore chemistry possible. Major discoveries like quantum mechanics often appear useless at first but later enable transformative technology, so the Higgs may have future applications we cannot yet predict. There is still value in continuing large experiments like the LHC because subtle discrepancies may reveal physics beyond the current Higgs model.

Data Points: Age gravity has remained essentially unchanged: 13.7 billion years - Malcolm says gravity has been pretty much the same for the age of the universe. Possible historical change in Big G after the Big Bang: about 10% - He notes that early-universe constraints limit how different Newton’s constant could have been. Temperature of hot electrons in a plasma TV: about 1000 degrees C - Kate explains energetic electrons in a plasma TV can be very hot even though the overall cell is much cooler. Overall temperature of a plasma TV cell: about 30 or 40 degrees - Kate contrasts the cold-plasma environment of a TV with fusion plasmas. Temperature of fusion reactor plasmas: hundreds of millions of degrees centigrade - Kate describes the extreme heat needed for fusion reactors. Insect travel distance to find a corpse: 15 kilometres - Erica uses this as an example of the strong scent-based range of some flies. Time scale for plasma TV changes: every millionth of a second - Kate says the plasma in a TV changes extremely rapidly. Research time on insect vision: about 50 years - Erica says scientists have studied the problem for decades without a definitive answer. Drosophila use in vision research: about 100 years - Erica notes fruit flies have long served as model organisms for vision studies. Time since first quantum theory breakthroughs: 1900 to 1925 - Malcolm references the period when quantum mechanics was developed before later applications like transistors.

Pivotal Quotes: "I recommend to people, by all means, try and come up with a better theory than Einstein. But first of all, learn what Einstein did first." — Malcolm Fairburn: He responds to people who send in claims that they have disproved Einstein. "Well, we don't know." — Erica McAllister: Her blunt answer on why insects are attracted to lights, before outlining competing hypotheses. "So in short, if all of that is passed you by, fusion devices contain truly hot plasmas... Plasma TVs contain cold plasmas..." — Kate Lancaster: She summarizes the essential difference between fusion and TV plasmas.

Implications: Listeners learn that many familiar phenomena still have unresolved scientific questions, and that foundational physics discoveries can take decades or centuries to become useful. The episode underscores the value of basic research and continued funding.