# “Is time travel possible ?” asks Lachie (9)

Thanks for the question Lachie . My friend is correct, Albert Einstein thought that time travel would be possible because of something he called relativity. It seems to be about the time it takes to move through a given distance (space) and the speed of light. The faster you go the slower the time that has past. That is a very, very difficult idea to understand. Even I find it difficult ….. but lets try and give you an example

Suppose you could move through space at or around or about 186,000 miles per second, which is the speed at which light travels?

Say you were 9 years old when you left Earth in a spacecraft traveling at about the speed of light (which is much faster than we can achieve now), and celebrated only five birthdays during your space voyage. When you get home at the age of 14, you would find that all your classmates were 59 years old, retired, and enjoying their grandchildren! Because time passed more slowly for you, you will have experienced only five years of life, while your classmates will have experienced a full 50 years.

So, if your journey began today in 2018, it would have taken you only 5 years to travel to the year 2068, whereas it would have taken all of your friends 50 years. In a sense, this means you have been time traveling.

According to Einstein’s ideas you can only move forward in time you cannot move backwards. However we do not at the present time have any vehicle that could reach the speed of light so if you want to travel in time you might have to wait a little while.
(revised 23rd May 2018)

# What happens to your eyes when you die? asks Olivia (12)

You did suggest Olivia that the eyeball might explode when a person died.  This is very unlikely. Look at the eye image below and try to identify the muscles in the eye. they will be attached to the two things that are constantly changing in the eye.

There are muscles attached to the lens and the iris.

When you die, your muscles relax. This causes the iris muscle contracts when this happens the eye is said to dilate ….like the image below

This is probably what your eye would look like  when you are asleep. Thanks for the question.

# Some Questions about the Solar System by Rishi, Ned, Maya, Thomas, Jackson, Adam and Pug.

Many thanks for the questions, and they are all about the Solar System. Amazingly I have just (three days ago) visited the Kennedy Space Centre in Orlando so they come at a time when I am excited by the science associated with space and space travel. I had questions before my visit and after it I had more. That’s the brilliance of these exhibitions, they raise questions. So let’s look at yours.

Rishi asked “How does the solar system work?”

I immediately think of why does it work in the way it does? The centre of the Solar System is the Sun. The Sun is one of a group of stellar objects called stars. Our star was named, by somebody, in the past, as the Sun.  Our star (the Sun) seemed to have attracted to it some massive lumps of matter/material which we call planets (planets are the biggest ‘lumps’ , the smaller ‘lumps’ are called asteroids and meteorites. What has given the Sun the ability to attract these ‘lumps’?

You then have the amazing thing that these lumps move around the Sun. They are attracted to the Sun but do not fall into it. They rotate around it, why do they do that? . Or does the Sun rotate around them?

So Rishi, your question is a great science question. From it lot’s of other questions arise, and that is what science is really about.

Ned asked “If the world split in half, would there still be a gravitational pull?”

Ned, thanks for the question. Gravity is one of those strange things called ‘forces’. Most forces are easy to define. You push things, you pull things by physically applying a force. Magnets  can push and pull so they can apply a force. So how can you explain the fact that things are somehow ‘pulled ‘ towards the Earth?  This seems to be something called a gravitational force. It’s strange. Nothing seems to be pulling or pushing you. Scientists have created a word called ‘gravity’ which describes the process of one object (of a big mass) pulling towards it a smaller mass.

We know that there is this force called gravity that exists. I am not sure that we have yet found out what causes it. We know that a very big object (of great mass) will attract a much smaller object (of smaller mass), however we have no idea why.

So at last to your question. My hypothesis (find out what that means). Slitting the world in half would mean that both halves of the Earth would move closer to the Sun because, the Sun is the biggest object in our Solar System.

Maya asked “What is the milky way?”

Maya, it’s a good question. I wonder who first used the name ‘the milky way’ and why? I firstly think about stars in the night sky, they produce white light (I wonder why – why not red or yellow light?). Does our star (the Sun) produce white or yellow light?

It is for a lot of us to really observe the night sky in all its glory. Why? It seems to be all the background light that we are experiencing when we look at the night sky. Go to a very dark place, away from the city, away from a near town and look at the night sky. You will see things you have never seen before. It is magical. You will see more stars than you have ever seen in your life. Only then will you see the Milky Way and only then will you know what it means.

Thomas asked “How many Suns are there in the universe”?

Thomas, thanks for the question. My first question is . What do you mean as Universe? As yet the investigation of the Universe in which we live is incomplete. We do not know how big it is. We do know, that the Universe consists of groups of stars that we have called Galaxies. We are in a Galaxy called the Milky Way (see Maya’s question). There are millions of stars in our Galaxy. So Thomas, in answer to your question ….we do not know …but the important thing is that you asked the question. By asking the question the quest and research for an answer continues. That is science.

Jackson asked “How big is Jupiter?

Jackson, a great question. It raised a question which I tried to find the answer to “Why do we want to know the size of Jupiter?’ I suspect it is to try to answer an even bigger question linked to Risha’s question. Why do the planets orbit the Sun? Is there some reason in there order of orbit …Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune?   Jupiter is the biggest planet in terms of mass and size in our Solar System . It would be nice if the size and mass of the planets and their orbital position was a straightforward order …but not so. That seems to be the outline of another question.

Adam, an interesting question, thanks.  It is thought that the Sun is 4.6 billion years old that is …would you believe it 4,600,000,000 years. Scientists reckon it was formed by the sudden compression of hydrogen and helium gas caused by the explosion of nearby star. Wow. This leads to lots of other questions …..think about them and let me know. The scientists also reckon that the Sun is about halfway through it’s life.

Pug asked “If all planets crashed into each other would it affect other Solar Systems?”

Pug, a good question. What do you think would happen if all the planets crashed into each other? How would it happen? Here is ia hypothesis. The most likely scenario would be the outer planets moving into a lower orbit and crashing into the lower orbit planets. They would then be affected by the gravitational pull of the Sun. They might then crash into the Sun. The Sun may therefore gain more energy and explode into a supernova. Pug, a hypothesis is an idea, can you come up with an alternative one? Let me know.

# “Why does the sky go green when it hails?” asks Swifty (11)

What a question? Thanks  team for your thoughts. To me it seems to be a unique mixing of the colours from our sunlight. We know that the blue sky is because of the blue part of the spectrum of colour that comes from the white light from the Sun.

Some of the blue part of that spectrum of light is scattered when it hits the molecules of Oxygen and Nitrogen in Earth’s atmosphere. So blue coloured light illuminates the daytime sky. We know that when we see a sunset we can see a red sky in the distance and that is because we are looking at the Sun through a lot more atmosphere than we would do in a normal day. This is the dust that is in the atmosphere. In the experiment the milk acts as a ‘dust’ in the water.

I attach a NASA video that explains this then I will tell you my ideas about a green sky.

My thinking, and that of some others, is that the green sky is linked to the storm clouds (the background image above, was a pause in the hailstorm that the cyclists were experiencing). These were preventing some of the sunlight reaching the viewer who saw a yellow light mixed with the blue sunlight. the mixture of these lights could have caused the green light (a cyano type of light, like that below).

Very happy to hear comments and questions. Remember science development is about admitting your ignorance and my thoughts above are just thoughts. You and I need to do some further investigations.

Revised 10/1/18 to include experiment and colour example.

# Keith (13) asked a question about thermal papers in cash machines.

Keith’s question
More and more places are using thermal paper as a form of receipt paper for customers. With time the information fades. How can one scientifically go about recovering information which may have faded from thermal paper.

Keith, many thanks for the question. I never realised that thermal(heat sensitive) paper was used in so many places and that it is also the basis on which the polaroid camera worked.

Thermal paper is made using a collection of dyes which exist as colourless crystals that become coloured when they interact with an acid.

For those who enjoy their chemistry you might have come across adding a dye called phenolphthalein to an acid solution. The dye changes from colourless to a deep purple.

The applied heat (from the cash register machine) melts a layer in the paper which contains acid crystals. The liquid acid then interacts with the layer below it which contains a colourless crystalline dye which changes colour as the acid interacts with it.  The print then shows. The acid quickly becomes crystalline again.

Over time the print does begin to disappear.

A little investigation.

Obtain an old till receipt which your adults do not want to save. Put it onto an ironing board and with a hot (care) iron, iron it.

Stop

To make it more scientific predict what you think might happen before you carry out the experiment. Any ideas, if so you have a hypothesis.  Now find a very old (fading) receipt and using a hair drier blow warm air onto the BACK of the receipt. Again predict.

I think I’ll stop there. Many thanks for the question Keith. Please comment or ask another question.

# Alice, Daisy, Eliza (10) asked “What chemical makes objects glow in the dark?”

Thanks team. I think we will start by looking at the meaning of the words that end in the term ‘escence’.

Fluorescence is the the almost instantaneous emission of light by a chemical that has absorbed light or some other form of energy and  then re-emits it.
Chemiluminescence is used to describe the production of light from a chemical reaction.
Bioluminescence is used to describe the production of light from a living organism. It is a form of chemiluminescence as it is chemicals within the organism’s body that produce the light.
Incandescence is the emission of light from a hot body. A heated piece of iron will glow.
Phosphorescence is the slow emission of light from a compound that has absorbed some energy, in some form…might be radioactive energy.

Note all of them involve , at one time gaining energy and then re-emitting it or chemicals moving from one state to another where the final state is of lower energy.(If you want to find out a little bit more on energy go to this Science Master Special)

If you have access to a low intensity UV torch ( check with an adult) you can look at at the compound Quinine for an example of fluorescence. Quinine is a compound in Tonic Water. In a dark room shine the torch (a UV torch produces BLACK light) on the bottle of tonic water and watch what happens. You can then make some ice lollies using the tonic water and again see if they are fluorescent.

Thanks for the question. If you want to make a comment feel free to do so in the box below…or maybe…you have a further question?
(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

# Ava (7) asks “Why do mirrors change words ?”

Ava, can you see how the image of the dog in the mirror is different from the dog. Look at the dogs raised ear. What side of the head is it on? NOW imagine you are the dog in the mirror, what side of the head is the raised ear on.

Try this, look in a mirror and point your right finger at the mirror. Now try to put yourself in the position of you in the mirror and what side of you is your finger. Is it your right finger or left finger, in the mirror???  Wow. The mirror has inverted your image (the dictionary says inverted means  – put upside down or in the opposite position.)

Now try a mirror with some words. Try it with this word  Mirror Me. Write it on a piece of card or paper and look at it in a mirror. What does it look like …..is it like this?

Think about what you are seeing. Why can you see the image in the mirror? Think about reflection? This is a very difficult area of understanding BUT you can have a lot of fun with it.

Updated 12/6/17

# “I know I can see myself in a mirror but why cannot I see myself in other things?” asks Isabella (8)

Many thanks team. I have some ideas about investigations that you could do at home. People say that light travels in straight lines. How can we test this idea. Firstly we need a source of light. How about a torch.

Now we know that a torch sends out light in all directions but how do we know if it is travelling in a straight line? Think……..

Now lets ‘capture a little bit of the light from the torch. Let’s use a piece of card with a hole in it and see if we can make the light from the torch go through the hole.

Now what do we have to do to show that, the little beam of light coming through the hole is travelling in a straight line?
Supposing we had another piece of card with a hole in it in exactly the same spot do you think you could arrange it so that the little beam of light goes through the hole in the new piece of card?

Do the same for a third piece of card arranging it so the little beam goes through it’s hole. Now draw a line between the torch and the third hole. What do you notice?

Now lets quickly look at your question about not seeing reflections in materials that are not mirrors.

Reflections are wonderful things and they happen, or do not happen because light travels in straight lines. A reflection occurs when a beam of light bounces off a surface. You could set up your torch and card above to make a reflection, using a mirror or something flat and shiny.

Now do the same for a different type of surface.try it with a piece of material. What happens? Try with all sorts of flat surfaces – shiny metal (use flat aluminum foil and then crinkle it), cardboard, paper, plastic, water, leather……..
What do you notice? Maybe reflection requires a flat shiny surface? Think about the results.

Thank you team. Some excellent observations. You noticed that the shadow had no detail on it, no colour, no lines, no images of seeds in the fruit. It was just black. On a dark night, under street lights look at your shadow. Other than your shape what detail does it have? It changes now and again, but why?

Now the reflection? If you look into a mirror what do you see? Is it like your shadow? How different is it?

Look at the two images of the fruit. The first image of the the fruit is the ‘real’ image. What about the image just below it (on the shiny surface)? Is it the real image? How did it get there?

You can create you own image of a reflection and a shadow. Get a mirror and a small screen. Put the object on the mirror and the screen behind it and use a torch to shine on the object.

Jack, this a great question. Lot’s to think about. Do you want to ask another question? Then click on the Reply button below.

# Beatriz (7) asks “What happens to the the light at night?”

How do we tackle this question Beatriz? Lets tackle it by looking at light being used.

Let us see if we can make light move around a table. For this experiment you will need 3 plastic mirrors some plasticine and a torch. Light can be ‘bounced off’ an object so can it be bounced off mirrors?

So your task is to bounce the light from the torch around the four sides of the table. Think about what you did to make it happen.

Also let us look at shadows. Collect a variety of objects, a torch and a screen (maybe mounted in some way). Shine the torch at the object, what do you see on the screen.

Why do you think the shadow is formed? Can you change the shape of the shadow? Can you get more than one shadow?