Experts weigh in on basic scientific principles and what they really mean

Lightning is an example of the plasma state.
Lightning is an example of the plasma state.PHOTO: AFP

How many states of matter are there?


There are three states - solid, liquid and gas.


"There are more states of matter that are present in extreme environments, such as plasma.

"Plasma is a state consisting of partially ionised gas, usually at high temperatures. As heat is added, the electrons fly off the atoms, resulting in a 'sea' of free-moving electrons, giving it the ability to conduct electricity.

"Lightning, electric sparks and stars are examples of the plasma state.

"The opposite of this is Bose-Einstein condensates, a state of matter in which atoms are cooled to near absolute zero, and they move so closely to one another that they combine and behave like a single atom."

- Dr Abel Yang, physics lecturer,

National University of Singapore.

Which colours are primary?


Red, blue and yellow are primary colours - which cannot be created by mixing other colours.



"The primary colours of pigment are cyan (greenish-blue), magenta (purplish-red) and yellow. The primary colours of light are red, blue and green.

"Red and blue are traditionally taught as primary colours... While cyan and magenta are technically correct, they can also be considered different shades of blue and red.

"The primary colours of light are red, blue and green because humans have three main receptors for these colours. Receptors are cells that are sensitive to light and relay messages to the brain.

"Combining red and green light, for instance, creates yellow light. These colours are used by light sources such as computer screens." - Dr Abel Yang, physics lecturer, National University of Singapore.

How many senses do humans have?


There are five senses - taste, touch, sight, hearing and smell.


Senses are bodily systems consisting of sensory cell types which respond to a specific physical phenomenon and correspond to a region in the brain, according to a Harvard Medical School report. Neurologists say there are up to 21 human senses.

"There are more than five senses. It's more a matter of categorisation and how much you want to split the senses. There are other senses, such as for temperature and pain, and being aware of the position of our bodies. These senses have different receptors, but they are all controlled by the somatic sensory system."

- Dr Ling Shuo-Chien of the Department of Physiology at the National University of Singapore's Yong Loo Lin School of Medicine.

"What we call senses are, in fact, extremely complex interactions between our physiological systems.

"The role of these systems is to detect changes in both our internal and external environment, and help prepare the body's response to maintain homeostasis (a state of equilibrium)."

- Dr Ciaran Forde of the Clinical Nutrition Research Centre at the Agency for Science, Technology and Research's Singapore Institute for Clinical Sciences

Is there gravity in space?


There is no gravity in space, which is why astronauts float around.



"Gravity is everywhere in the universe. On Earth, we feel gravity because it is pulling us towards the ground. In space, shuttles are in a state of continuous free-fall towards Earth, so astronauts appear weightless because they and the shuttle are falling at the same speed.

"The strength of gravity depends on the mass of the two objects and the distance between them. An object with larger mass has more gravitational force; that is partly why all planets and comets in our solar system orbit the Sun." - Dr Abel Yang, physics lecturer, National University of Singapore.

How does the tongue taste food?


Various parts of the tongue are exclusively responsible for different tastes. The taste buds for bitter, for instance, sit at the back of the tongue, and those for sweet are right in front.


Tongue taste maps first appeared in 1942, after American experimental psychologist Edwin Boring from Harvard University misinterpreted a German study from 1901. The theory was discredited in 1974, but tongue taste maps still appear in biology textbooks.

"Taste buds are distributed all over the tongue. Each taste bud contains between 50 and 100 taste receptors, capable of detecting one of the basic tastes of sweet, sour, salty, bitter or umami (pleasant savoury taste).

"No distinct region of the tongue is more sensitive to one of these tastes than other parts."

- Dr Ciaran Forde, the Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research.

A version of this article appeared in the print edition of The Straits Times on July 03, 2015, with the headline 'Experts weigh in on basic scientific principles and what they really mean'. Print Edition | Subscribe