## What is Determinism?

Determinism refers to the idea that the future is not up to chance, the future can be predicted. Determinists claim that if you had sufficient knowledge of the current situation, then you could in theory predict the behavior of a system into the future. Certain systems are indeed deterministic, many others are not.

In this edition we will have a look at the concept of determinism. In a deterministic system the initial conditions of the system determine the future behavior of the system. The behavior of both a falling apple and a rolling die depend on the initial conditions. Even the same laws of physics apply, namely classical mechanics. Both falling apple and the rolling dice are deterministic systems. But I am able to calculate the landing position of a falling apple, but I am not able to calculate the result of a die roll. Why? How are these two examples different? Why does the die seem to behave according to chance, but not a falling apple? A rolling die is chaotic and it is unpredictable, even though it is deterministic. Even if we know all the physical laws and the starting conditions of a system, it is still not possible to predict the future behavior of chaotic systems.

## What are Thought Experiments?

It is not always necessary to conduct real-life experiments to reach a valid scientific conclusion. Thought experiments may in some cases also suffice. In this edition I will illustrate you a thought experiment from physics: In a vacuum, all objects accelerate the same way and they both have the same velocity. Heavy objects will not fall faster. But how can we test this? We do not have a large vacuum chamber to test this. A thought experiment can be useful in this case.

In this edition of TOK-Talk I will explain you what a thought experiment is. Is it always necessary to conduct real-life experimets to reach a valid scientific conclusion? Listen to find out!

## What is the Observer Effect?

Every measurement changes the object that we want to measure. This is called the Observer Effect. When we stick a thermometer into a glass of water to measure its temperature, then the thermometer will change the temperature of the water as well. Similar effects can be observed when measuring voltage or current in electrical circuits. Also in the social sciences we have a similar problem: people will not behave naturally when they feel that they are observed.

In this edition of TOK-TALK we will explore if it is in principle possible to measure anything accurately. How does a measurement change the value of that what you want to measure? Listen to find out!

Here in front of me, I have a cup of hot water, and over here we have a thermometer. Let’s put the thermometer into the glass, we have to wait a bit for the temperature reading to adjust. For our listeners, it’s a digital thermometer with a metallic probe. You use similar thermometers to measure the inside temperature of a cake to check if it is finished baking. Continue reading »

## What is the Mpemba Effect?

In this edition I would like to explain why hot water freezes faster than cold water, when put into the freezer. It is a very counter-intuitive observation, it’s a paradox. This is called the Mpemba Effect. The effect is named according to Tanzanian high-school student Erasto B. Mpemba who re-discovered the effect while making ice-cream, back in 1963. The Mpemba Effect is a nice example how the change of one variable, the temperature, can have unexpected side effects. Most people assume that the difference between a hot glass of water and a cold glass of water is only the temperature. But this is not the case. Just by heating the water we are introducing a range of other variables that have an unexpected effect on the outcome.

In this edition of TOK-Talk I would like to explain why hot water freezes faster than cold water, when put into the freezer. How is this possible? Listen to find out! Continue reading »