“Questions about the Universe” by Lewis Jordan Sexton (13)

Questions about the Universe??????

Lewis, thank you very much for your thoughts and the questions in your own mind that you are thinking about. Wow.

I’m tempted to tell you a story about a question that my wife asked to her mother when she was about your age. “Mother what is the Universe and what was the big bang?” Her mother’s reply was “They are very big questions, I think your time is better spent making sure that this planet we are living on lasts as long as possible, rather than worrying about the Universe”

For readers who are interested here is the what Lewis submitted. Lewis, if you would like me to remove it send a request in the comment box below.

My thinking is that we have no idea, at the moment, whether any of the the thoughts put forward by various scientists are valid. It seems to me to be a classic case of a set of developing scientific ideas as the tools and thoughts of the the scientists develop.

For example notable scientists like Newton and Einstein developed ideas relating to your thoughts  which were effectively disproved. This is in fact the way that all scientific arguments progress. For example ……When Albert Einstein was formulating his ground-breaking theory of gravity in the early 20th Century, at a time when astronomers only really knew of the existence of our own galaxy, he used the simplifying assumption that the universe has the same properties in all its parts, and that it looks roughly the same in every direction wherever, in the Universe, an observer happens to be located. Like Sir Isaac Newton two hundred years before him, he assumed an infinite, static or “steady state” Universe, with its stars suspended  motionless in a vast void.

One of the driving forces behind the development of science thinking is to disprove earlier scientific thinking. It is called falsification.

It was a philosopher,Karl Popper who said you can only have a scientific theory if it can be proved to be false. This is what has happened to the scientific theories of Einstein and Newton. Some of their ideas/theories on gravity and the nature of the Universe have been successfully disproved. New theories by Hubble (the telescope scientist) disproved the stable Universe idea’s of Newton and Einstein. This led to new scientific ideas of an expanding (rather than a stationary static state)  Universe …which could be false? To illustrate how scientist are challenging Hubble’s ideas it is now known that the Universe is expanding at an accelerating  rate than rather than a steady rate …….the mystery continues. 

Have a look at this website The Physics of the Universe.

I shall continue thinking and possibly updating.

Thanks again for your thoughts.




Lachlan(12) asks “How does a trebuchet work?”

Lachlan – my first question is what is a trebuchet?

Simple answer …It’s a type of catapult.

Here is an image of  a very early trebuchet


Here is an image that may help your understanding and give you some clues on how the trebuchet works. When the mass 1 is released it begins to accelerate towards the ground. In doing so a force is applied to the beam pulling it down. That force is then applied, via the beam to the mass 2. What do you think will happen to Mass 2?

The support for the beam, the fulcrum, is in a particular position. Any thoughts on that? You could create a see-saw and investigate the application of forces when the fulcrum  changes position ……altering d1 and d2.

Ronan (10) asks “How do stars form?”

Ronan ..this is my thinking about your excellent question.

Yes it is all about Gravity – There was a previous question by Tegan on Gravity. Have a look at it.

It is thought (it is therefore a hypothesis – an unproven idea)  that dust and hydrogen gas from the ‘Big Bang’ was gravitationally attracted to each other.

As the mass of the dust and gas got bigger it’s gravitational pull got bigger and the more dust and gas it attracted.

Eventually  the compact squashed ball of dust and gas started to heat up. It got hotter as it got bigger and eventually the particles of dust and gas began to break up in this hot environment and the hydrogen particles began to come together to make new particles … an atomic FUSION reaction began to occur and the star was born.

Yet more questions on Space and the Solar System from William, Kylan, German, Rob, Aidan, Gavin, Lucas, Jake, Thomas and Kylie.

Hello, yet more interesting questions. Many thanks. It is brilliant that you continue to ask questions. By doing so you maybe think that you are showing your ignorance, and you are. However it is important that you do show your ignorance because that is the way that knowledge and science develop. Scientists are constantly saying “I do not know how that happens” then “I will try to find out why it happens”. My answers to your excellent questions below might therefore not be direct answers but may be directed to helping you to find the answer yourself. You can be the scientist. Here we go …..

William asked “How many stars are there in space not including the Sun and what is the hottest planet in the solar system?”

William, the difficulty I have with this question is what do you mean by Space? Space is endless so for an investigation it is better to start with a smaller known area …such as our Galaxy, the Milky Way. Even then the answer is only an estimate ….about 1000,000,000 (a billion stars) and apparently it has been estimated that there are over 1000,000,000 Galaxies in Space.

Maybe the second part of your question has an easier route to an answer. Initially one might have thought that Mercury would have been hottest – it is the closest planet to the Sun! But I am wrong, Venus is the hottest, because of its atmosphere. Why do you think this is?

Kylan asked “Is Space endless?”

Kylan, the answer to this is YES. To us humans this must be a difficult thing to grasp. We are constantly living within confined areas. To think of something as endless is difficult to comprehend.
Kylan, a great but disturbing question.

German asked “Como se origino el universo?”

German, another difficult question. You are obviously in a group who specialise in asking difficult questions. That is brilliant, because that is what science is about, asking difficult questions. There is evidence that the Universe began some 14.8 billion years ago, the Big Bang. This evidence apparently comes from a something called CMB (Cosmic Microwave Background). I think I will leave it there. I have no doubt that the Big Bang idea will at sometime in the future be challenged. Another thing about science is that scientists are always trying to falsify other scientist’s theories (prove them wrong).

Rob asked “Why no one can go to the Mars?”

We will get there Rob. When I was at the Kennedy Space Centre there was a lot of talk about the proposed trip to Mars. They are even now investigating how astronauts can live in a small self contained environment for a number of years. We have got to the Moon, which is 384,000 km away, for Mars we will have to a travel a minimum distance of 54,600,000 km. Why do I say ‘minimum’ distance for the Mars trip and not the same for the Moon trip?

I think it may happen in your lifetime.

Aidan asks “Why doesn’t NASA use a Saturn V rocket to go to Mars?”

They have a Saturn V rocket at the Kennedy Space Centre. It is massive. However they will need a more powerful (notice I don’t say bigger) rocket to launch a Mars probe which includes astronauts. The living module will have to be a good deal bigger than that used to get to the Moon and back.What do you think will be necessary for the astronauts survival?

An image of the engines of the Saturn 5 rocket  at the Kennedy Space Centre


Gavin asked “How does the Solar System work?”

Gavin, great question. I have already answered a similar question in a previous post. This was my answer to Rishi:

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?

Lucas asks “How big is our solar system and do humans know if there are other solar systems?”

Lucas, NASA has a project called Keppler that is looking at other planetary systems. Below is an image of the space telescope that is doing this work. Note that our planetary system is the only one called the Solar System. All others are called planetary systems. The Kepler telescope has identified a number of other planetary systems and some of them are very strange. One system has two stars. Quite a few have Earth like planets. I wonder what it would be like living on a planet with two stars?

Jake asks “Will Mercury crash into the Sun in a million years?”

Jake, it is unlikely that Mercury will crash into the Sun. It is thought that as the Sun gets older, it is now about 4 million years old, it will begin to expand  and eventually destroy Mercury and Venus and the Earth. It is reckoned that this is likely to occur in 4.5 million years time.

Thomas asks “How does the Sun create radiation?”

Thomas, how many types of radiation do you know about? There is visible light radiation,  ultraviolet light radiation, and infrared radiation.  However, there is another type of radiation which produces all of these types of radiation.

The Sun’s radiation is created by a nuclear fusion reaction in its core. This nuclear reaction produces very high energy gamma radiation which, as it passes from the inside of the Sun to the outside, is converted to the other types of radiation listed above.

Kylie asks “Why does Saturn have rings?”

Great question Kylie. Saturn is one of the largest planets in our Solar System. It therefore has a great gravitational attractive force. It has 60 Moons! It is thought that the rings have been created by this gravitational force attracting lots of the bits and pieces that each year enter our Solar System. Bits and pieces like asteroids and meteorites. Gravity is an important feature of our Solar System. Have you any questions about Gravity? I would like to hear them.

Some more questions about the Solar System and Space by Seb, Luke, Luca, Sammy and Bowen

Many thanks for your questions. I told the last group that, 3 days ago I visited the Kennedy Space Centre in Orlando. It was brilliant. I was particularly interested in their idea to visit Mars in the near future. However let us look at the other superb questions and see how many other questions they create….that is what science is about.

Seb asked  “What does Mercury orbit?”

Seb, many thanks for the question. Not long ago, in our history, everybody thought that the Sun orbited the Earth. Why shouldn’t they? You see the Sun rise everyday and move across the sky and then disappears on the opposite horizon. It moves, we don’t.

Or could it be the other way – the Earth moves and the Sun stays in the same place? This was a question that a early scientist Copernicus (1473-1543) thought about and and then Galileo Galilei (1564-1642) confirmed ..it was the Earth that orbited the Sun. With this knowledge other scientists (we call them astronomers) worked out what Mercury orbited. What do you think?

Luke asked  “Do Saturn,Neptune or Venus orbit any planets other than the sun/orbit each other?”

A question I think that is linked to Seb’s. What evidence would you think would show that a planet orbited another planet? Think about the Moon, what does that orbit? Does it orbit the Sun? Supposing it did, what would you observe?  It was Galilei who built a telescope that would enable observations of the planets and therefore provide evidence which would answer the question. Like all science once the hypothesis has been made it can only become an accepted fact after relevant observation and production of evidence.

Luca asked “What is the furthest distance of a spaceship travel?” and “What is space made of?”

Luca, two great questions. For the first question I must admit I have no idea. From my visit to the Space Centre I know that NASA is planning to go to Mars. I see no reason why humankind will not be able, in the future, to leave the Solar System. We can already send satellites and other objects beyond the Solar System.

To your second question, the easy answer is ‘nothing’, other than stars, planets, asteroids, satellites and other bits an pieces. It does however contain what would be called ‘radiation’ of different types, otherwise we would not be able to see stars, the Moon or the Sun. Do you think it could contain anything else?

Interestingly, in Earth orbit, you would not be able to see any stars in space? Any ideas why?

Sammy asked “Can a black hole swallow Earth? If so when could this happen?”

Sammy, what do you think a black hole is? Why do you think it is called a black hole? I think it is something to do with that magical force called gravity. Think about gravity.  What does the gravitational force that an object has, depend upon?  Think about the force that pulls you to the ground. Think about the force that keeps the Earth in orbit around the Sun. Think about the force that holds the Moon in orbit. A black hole is a hole which light has been pulled into it, by a gravitational force. Think about a gravitational force that can pull light into it …….will it be able to swallow the Earth?

Sammy …something I didn’t know. It is thought that all galaxies have a black hole. Even our Milky Way galaxy has its own black hole.

A NASA photograph of a black hole. There is one…its a dot in the middle of the bright circle in the middle of the picture.

Bowen asked “Why do humans still think that there are resources on the moon? I think there are none.

A interesting question Bowen which I would like to challenge. Why do you think there are none? My thinking is that the Moon seems to be made of rocks and rocks are sources of all sorts of things. A lot of rocks contain silicon, what do we use silicon for? A lot of rocks (moon rocks included) contain aluminum which is used in a variety of ways, the rocks also contain hidden oxygen, a lot of rocks exist in the form of oxides (iron oxide is an example). Probably the biggest resource that the Moon has  is a low gravity. Any ideas why that is so important? Let me know.

Tegan (10) asks “How does gravity work?”

Tegan, a very interesting question. This question was asked some time ago and this is what my team said.

In the 17th Century Newton and another scientist called Hooke did some great observations and experiments on falling objects and proposed that gravity was an attraction between any two masses AND the attraction was dependant on the size of the masses involved.

For example you are attracted by the Earth and the Earth is attracted by you BUT your attraction is so much smaller than that of the Earth it does not affect the motion of the Earth. The attraction between you and the Earth is also dependant upon how far away you are from the Earth. The Moon is attracted by the Earth and the Earth is attracted by the Moon. They are both big bodies so gravity does affect the way they move with respect to each other and this dictates how the Moon orbits the Earth.

Some scientists including Einstein have put forward ideas on how gravity operates but even these are being challenged. There a lots of things which are still unanswered. The questions just have to be asked. Thank you for asking it.

revised 15/01/08 …experiment added.

“If I was sucked into a black hole what would make me die?” asked James (12)

James, thank you for your question. I had a similar question from  Sheereen  click here to see my, and my friends answer.

It is thought that a ‘black hole’ is produced when a rather large star comes to the end of it’s life. It collapses in on itself and forms an object of incredibly concentrated matter. As ‘gravity’ is a property of the quantity of matter (see my answer to Ernie’s question) the collapse causes an immense increase in the gravity from the  smaller collapsed star.  

It is unlikely that our Sun would end in this way as it is classified as a smallish star. It is likely to become something called a ‘Red Dwarf’ star.

The ‘black hole’ is explained by the fact that this concentration of gravity ‘pulls’ light into it, thus the ‘hole’.

Now if you were close to the collapsed star in your spaceship you would also be pulled into it and unfortunately be added to the mass of the collapsed star. Sorry, you will be crushed.

(slightly revised 20/4/2016)

“If I do a headstand will my brain get too much blood?” asks Susan (8)

Susan , I asked my friends about your question and this was their thoughts.

Thanks team, some interesting thoughts. Firstly let’s confirm that it is the heart that pumps the blood around our bodies. In a normal situation the heart is strong enough to pump the blood up to our head, so it might find it easier to pump the blood to our head when we are upside down. Any idea why? Think of gravity.

When you are doing a headstand the heart will not need to fight gravity to get the blood to your head, so it might find it a bit easier. It does however still need to get the blood to your feet (which are now above your heart) but it is strong enough to do this.

There might be some visible signs in the way the blood circulation changes. If blood has a little difficulty getting to the feet they might go a little pale. If the blood does not leave the head as quickly as usual, the face might go a little red. You might also get a change in the pulse rate if the heart has to work harder. These can all be tested with a healthy volunteer.

(edited 19/01/2017)

Ernie(13) asks -“What is at the centre of a black hole? What would happen if you fell into one?”


We obviously know something about gravity. We know that it is a force that is generated by the mass of an object. The bigger the mass the bigger the force that it exerts on other objects. So we feel the force of Earth’s gravity on us and the Earth feels the force of the  Sun’s gravity on it. The Sun’s gravitational force keeps the Earth on an orbit around it. If it didn’t exist the Earth and all the other planets would start wandering in space.

Black holes are thought to be a source of a massive gravitational force, because of their mass , which is constantly increasing, and they don’t just pull other matter to them they pull light in as well …thus a black hole. No light – darkness.

So to your question.  I think you could now answer that yourself.

“Can u jump off the world into space?” was Austin’s question.

A great question Austin however I think you are going to be a little bit disappointed by my friends answers.

falling to earth

What a way to hand over to me!

To think about gravity you have to think about the really big things. the gravity of the Earth pulls on the Moon and keeps it in orbit. The gravity of the Moon pulls on the Earth and causes the tides. So gravity doesn’t end when you leave the Earth. Austin, jump and you will fall a long, long way.


Those astronauts are falling all the time but because they are moving around the Earth the ground is constantly moving away from them. If there spaceship stopped moving around the Earth it will fall and hit the ground. (revised 10/09/16 -miscalculation 13/09/16 new animated gif)