In history of the earth, there have lived at least two million different species of life. But no other species like human beings have so much impact on the earth, on the environments, and on other lives. It is because of making and using of tools that make us so powerful and distinguish us from animals.
Tools extend our biological capabilities. For example, cars extend our capability of walking, telephones enable us to hear people from thousands of miles away, and telescopes make it possible for us to see far away in the space.
A microscope is a tool or an instrument that helps us to see objects that are too small to be seen with the naked eyes. Here shows a picture of a microscope. The main parts of a microscope are eyepiece lens and objective lens. And both eyepiece and objective lens are magnifying glasses.
It is recorded that as early as 2000 years ago, people already knew that some glasses or crystals with thicker in the center and thinner at the edge could make things look larger. And that was why they were called magnifying glasses. But magnifying glasses were not used much until invention of spectacles in the end of the 13th century.
In about 1590, two Dutch spectacle makers, while experimenting with several lenses in a tube, discovered that objects appeared greatly enlarged. That tube containing several lenses in it was the forerunner of both microscopes and telescopes.
Two remarkable contributions were made with microscopes in science: discovery of cells and discovery of microorganisms such as bacteria and virus. Discoveries of cells and microorganisms were milestones in development of science and had great influence in development of biology and medicine.
There are many different kinds of microscopes. But basically they belong to two kinds: optical microscopes and electron microscopes. Optical microscopes use visible light to image objects, and electron microscopes use electron beams to image objects. The magnification of an optical microscope is usually 500 to 1000 times. The maximum is 2000 times. An electron microscope can reach magnification of 2,000,000 times, under which virus and large molecules can be seen.
Here are images of pollens under microscopes. Pollens are male cells of plants. They are reason or culprits for allergy many people suffer in the spring. The left is an image of pollens under a optical microscope and the right is an image of pollens under an electronic microscope.
Microscopes are indispensable tools in fields like cell biology, microbiology, pathology including plant pathology, animal pathology and human pathology, nanoscience that deals with materials at micro level and forensic science that deals with criminal investigation etc.
Human beings have actually found another world with microscopes.
---
The above is one of my Toastmasters speeches. The speech is based on a project titled "Technical Briefing".
