Natural Science

Key Vocabulary

• prolific - 多产的 (producing much fruit or foliage or many offspring; very productive)
• empirical - 基于经验的 (based on, concerned with, or verifiable by observation or experience rather than theory or pure logic)

Articles

The Birth of Photography (摄影术的诞生)

Source: TPO22 Reading Passage 2

Photography represents one of the most significant technological innovations in human history. The development of photographic techniques revolutionized how we capture and preserve images, replacing traditional artistic methods and creating new possibilities for visual documentation.

Vocabulary

• camera obscura - 照相暗盒 (a darkened room or chamber with a small hole, producing an inverted image of the scene outside)
• silvered copper plate - 镀银铜板 (copper plate coated with silver, used in early photography)
• daguerreotype - 银版照相法 (an early photographic process using a silvered copper plate)
• calotype - 碘化银纸照相法 (an early photographic process using paper coated with silver iodide)
• revolutionary - 革命性的 (involving or producing radical change)
• authenticity - 真实性 (the quality of being genuine or real)
  • authe- prefix meaning truthfulness
• obsolete - 过时的，废弃的 (no longer in use; out of date)
• portrait - 画像，肖像 (a painting, drawing, or photograph of a person)
• emulsion - 乳液 (a fine dispersion of one liquid in another, used in photographic film and paper)
• candid - 坦率，真诚 (truthful and straightforward; frank)
• unposed - 未摆姿势的 (not deliberately arranged or positioned)
• cropping - 裁剪 (selecting or cutting part of an image)
• trimming - 修剪 (removing excess from an edge or border)
• imposed - 强加于 (forced to accept or endure something)
• accidental - 偶然的，无意的 (happening by chance rather than by intention)

Key Sentence

The rapid technical development of photography—the introduction of lighter and simpler equipment, and of new emulsions that coated photographic plates, film, and paper and enabled images to be made at much faster speeds—had some unanticipated consequences.

This sentence highlights how technological improvements in photography led to unexpected social and cultural impacts, as the equipment became more accessible to the general public and photography could capture candid, unposed moments in everyday life.

Lightning (闪电)

Source: TPO18 Reading Passage 3, Question 1 (100% accuracy, 30 minutes)

Lightning is a natural phenomenon of extraordinary power, representing one of nature’s most visible and dramatic electrical events. Understanding the physics behind lightning has important implications for safety and meteorology.

Vocabulary

• lightning - 闪电 (a flash of bright light produced during a thunderstorm)
• electrical discharge - 放电 (the release of electrical energy)
• take place - 发生 (occur; happen)
• metal flagpole or tower - 金属旗杆或塔 (tall structures that attract lightning due to their conductivity)
• attractive tension - 吸引力，张力 (the force pulling opposite charges together)
• ice pellets - 冰粒 (small particles of ice in clouds)
• ice crystals - 冰晶 (frozen water crystals suspended in clouds)
• updraft wind currents - 上升气流 (upward-moving air currents in clouds)
• thickness - 厚度 (the extent of something from side to side; vertical measurement)

Explanation of Lightning Formation

Lightning is a brilliant flash of light produced by an electrical discharge from a storm cloud. The electrical discharge takes place when the attractive tension between a region of negatively charged particles and a region of positively charged particles becomes so great that the charged particles suddenly rush together. The coming together of the oppositely charged particles neutralizes the electrical tension and releases a tremendous amount of energy, which we see as lightning. The separation of positively and negatively charged particles takes place during the development of the storm cloud.

Key Process:

1. Charge separation - Ice pellets and crystals collide in the updraft, creating positive and negative charge regions
2. Tension buildup - The attractive force between opposite charges increases
3. Electrical breakdown - The attraction becomes so strong that electrons rush between the regions
4. Energy release - This rapid electron flow releases enormous energy as light and heat

The Mystery of Yawning (打哈欠)

Source: TPO18 Reading Passage 2

Yawning is a common human behavior, yet its true function remains a scientific mystery. Despite numerous theories, research has consistently challenged popular explanations for why we yawn.

Key Terms

• yawn - 哈欠 (n./v. to open the mouth wide involuntarily as a sign of tiredness or boredom)
• empirical - 基于经验的，经验主义的
  • Definition: Based on, concerned with, or verifiable by observation or experience rather than theory or pure logic
  • Key concept: Based on actual observation and real-world testing

Understanding “Empirical”

Empirical knowledge is based on observation, measurement, and experience—not just abstract theory. For example:

• In medicine: Most medicine is empirical—doctors give patients medication and observe whether they improve
• In language learning: An empirical approach emphasizes listening and speaking practice over pure grammar theory
• In science: Theories are tested empirically through real-life experiments
• In statistics: We gather observational data to verify hypotheses

The core principle: If something is empirical, it’s based on observation of real life, not just theoretical prediction.

The Tiredness Theory and Its Flaws

One common theory suggests that yawning helps us stay alert by increasing physiological activity. However, research has consistently contradicted this.

Research Findings:

When researchers measured heart rate, muscle tension, and skin conductance before, during, and after yawning, they found:

• Minor physiological changes in skin conductance following yawning (slight increase in activity)
• However, similar changes occurred when subjects simply opened their mouths or breathed deeply
• Conclusion: Yawning had nothing special to offer for physiological activity

Oxygen Theory Debunked

Another hypothesis proposed that yawning responds to drops in blood oxygen or rises in blood carbon dioxide. Experiments definitively showed this was false.

Experiment 1:

• Volunteers were told to think about yawning while breathing:
  • Normal air
  • Pure oxygen
  • Air with above-normal levels of carbon dioxide

Expected results (if theory was correct):

• Extra CO₂ should trigger yawning
• Pure oxygen should suppress yawning

Actual results:

• Neither condition made any difference
• Yawning frequency remained constant at approximately 24 yawns per hour

Experiment 2:

• Subjects performed vigorous physical exercise that doubled their breathing rate
• Result: No effect on yawning frequency

Implication: Yawning has little or nothing to do with oxygen levels in the blood.

The Unanswered Question

Despite ruling out several theories (tiredness, increased alertness, oxygen regulation), the actual function of yawning remains unknown. Scientists continue to investigate:

• Evolutionary perspective: Why has yawning persisted in human behavior?
• Social function: Does yawning serve a communicative purpose (yawning is contagious)?
• Neurological role: What brain mechanisms control yawning?
• Thermoregulation: Some recent research suggests yawning may help cool the brain

The mystery of yawning demonstrates how careful empirical research often reveals that common assumptions about human biology can be wrong.

Study Notes

Research Methodology in Science

When studying natural phenomena, scientists follow the empirical method:

1. Observation - Notice a behavior or phenomenon
2. Hypothesis - Propose a theory explaining it
3. Prediction - State expected outcomes if the hypothesis is correct
4. Experimentation - Test the hypothesis through controlled experiments
5. Analysis - Compare predictions with actual results
6. Conclusion - Accept, modify, or reject the hypothesis based on evidence

Key Takeaway

Good science relies on empirical evidence—not assumptions or intuitive beliefs. The studies on yawning and oxygen levels show that even widely accepted beliefs can be overturned by careful experimentation. This is why the scientific method remains so powerful: it constantly challenges us to verify our assumptions against reality.