How radioactivity was studied

today I want to write about radioactivity. It is rather new concept which is not very surprising as the process of radioactive decay is not very visible and the effects (on health for example) are not so clearly connected since they usually have long time span. Probably largest work done on this topic was by Marie Curie and her husband Pierre.

This is how radium dials looked like, cute!

Curie was from Poland. She had kind of difficult childhood since women were persecuted at that time in the east and it was hard for her to find place to study. Later on, she was able to move to Paris with her sister. There she met Pierre with whom she had two kids.

The first time she encountered with radioactivity was when she measured pitchblende [1] and uranium and how much radioactivity they  were “giving off”.

She expected that pure uranium would be much stronger but this was not what happened, what she found was exact opposite. Later on, thanks to this she found out two new elements: Polonium and Radium.

At this time it was not yet known that you can get pretty easily cancer by being close to radioactive stuff. Curie and Pierre were buying tens of kilograms of pitchblende to do their research and prove those two new elements since lot of other scientists were kind of sceptic about it.

In November of 1898 they extracted compound that was 900x more radioactive than uranium, you can see where this was going.

In 1902 it was announced that one decigram of radium chloride was succesfully isolated.

Four years later Pierre died when wheel of carriege run over his skull, this was because of the effects of radioactivity, at this point he was not really able to use his hands, they were pretty much destroyed by the pitchblende and his whole health was in very bad state.

In 20′ it started to be more and more clear that there is something wrong with the stuff. There was actuall factory that painted dials with radium (not pure of course), this is because it glows nicely and everyone liked it. The brushes that were used for this had to be kept sharp and this was done by lips. For this work about 4,000 people were hired, the so called “Radium Girls” was a group of women that also painted for fun their nails, face and teeth, noone knows how many sacrifices this caused.


[1] Pitchblende is mineral that is radioactive since there is uranium and other heavy elements. Lot of miners in extreme conditions died because they were mining it.


Your phone is NOT killing you

today I want to write about ionizing and non-ionizing radiation and also mobile phones as serial killers.

When somebody says radiation they mean electromagnetic radiation. Light is of course an electromagnetic radiation but only small part that we can see.

Visible light makes only very small part of whole spectrum.

The energy of light is connected with its frequence, as it rises (to left) energy increases as well. Gamma rays are the most energetic part of spectrum, they appear in radioactive decay and the are also created in Sun. Radiowaves on the other hand have enormous wavelength and very small energies, this is very good because it means that they are easy to create and also not harmful to human.

When we talk about radiation we can say that it is either ionizing or non-ionizing. If it is ionizing it means that it can create ions. Ions are either positively or negatively charged atoms, ions are created when they get or lose an electron which happens when photon hits the electron, but not always. If the energy of the photon is high enough then it will happen (ionizing) but if it is not the nothing will happen (non-ionizing).

How does this corresponds to your phone?

Well there have been some studies that showed that frequent phone users had higher chance of getting brain tumor. This would be caused by the photons that are transmitted from your phone. They should apparently hit DNA and other stuff in your cells and by ionizing these atoms, make change and possibly develop cancer.[0]

The radiation that is used in your phone is with the wavelength of tens of centimeters which means something like low radiowaves. Photons in this part of spectrum would not be able to knock electrons from atoms at all [1].

While for example study from Sweden showed that brain tumors and phone usage correlates, the study was not so well made. The problem is that you need gigantic sample since brain tumors are very rare (3/100,000 people). In short, the best thing you can do is to look on the number of brain tumors before “everyone” started to use cell phone and compare it to the number brain tumors right now…


There is no correlation whatsoever!


If you want more detail about the studies and so on, check out these two videos:

[0] I was just thinking that if radiowaves cause cancer than we should probably be much more conserned about ultra violet that is roughly million times stronger!

[1] Einstein got Nobel prize for finding the photoelectric effect which is basicly the knocking of electrons by photons. He found out that under certain frequency the atoms will not be ionized because the energy is not high enough (this critical point is different of course for different elements).



Gravitational waves

before I start to write about gravitational waves, let me explain how electromagnetic waves work.

Electromagnetic waves are just light which we see from candle for example. The thing is that in such a candle atoms oscillate and in the process of burning electrons are jumping on more energetic levels, orbitals. When this happens they want to go back right away, so they emit photon and fall back on the lower orbital. Such a photon then travels towards you and you can sense it with your eye.

But all of those atoms oscillate because there is huge temperature in the candle (800°C). They move back and forth creating waves of photons because some photons are closer together as the atom moves to the maximum of oscillation. As it goes back the photons are more stretched apart creating the gap in the wave. This is called electromagnetic wave.

If you had really good eye and somebody would walk away from you with candle, the light would not stop but you would observe the light come towards you in wave, in quantum. The frequency would get smaller and smaller but it would never disappear and would always appear with the same luminosity.

Now when you have gravity this can happen too in what is called gravitational wave. Such a wave is a result of shaking with something that interacts with gravity. The problem here is that gravity is such a weak force that you just can not observe it on candle and you need some kind of star.

Here comes two neutron stars which were found to be rotating rapidly around each other. As they rotate they create the ripples in space time, gravitational waves. In 1993 the Nobel prize was awarded to two guys who were able to indirectly observe how this system of two neutron stars was losing energy emitting those waves, they were observed to be slowly getting closer and closer to each other.

Physicists are trying to observe gravitational waves directly with tremendously precise methods using lasers but it was not yet achieved.


Picture is from here.


Moons of our Solar System: Europa

here comes the post about another moon of our Solar System. This time it is Europa. Europa the awesome moon with so white surface and those red streaks across but still the smoothest crust, Europa another Galilean moon!

Europa is very famous moon. It is also very large, sixth moon in whole Solar System and 15th object in size in whole System.
Europa-moon.jpgLike all other Galilean moons this one was also discovered by Galileo Galilei who named it Jupiter II and independently by Simon Marius who called it Europa after Zeus’s lover.

I think that Europa is very well known do to popularization of high chance of extraterrestrial life there. Probably also because of that enormous water ocean under its surface.

First of all lets look at its enormous size.

On the right you can see for comparison the size of Europa, Moon and Earth.

Mean radius of Moon is 1,737 km while for Europa it is 1,560 km. Mass of course is lower. This corresponds with density. There is 0.3 g/cm3 difference, which is not much.

Moon orbits at 380,000 km while Europa at 670,000 km. As I said in previous posts Ganymede, Io and Europa are in orbital resonance.

This means that Europa’s interior is heated by friction.

Surface of this moon is the smoothest in whole Solar System. This seems to be from the process of water running from under the crust of ice and smoothing everything out. While there are no high features, you can find there things called penitentes. Those can appear on Earth in high altitudes when snow sublimates in temperatures below zero. It creates those snowy spikes.

If you look on the first picture of whole satellite you can see that there are those red stripes.
It seems that they are created by “hot” ice flowing sometimes from under the surface. This also hints to plate tectonics on other object than Earth.
There is extreme radiation on Europa, about 5,400 mSv which is a lot and it would kill you in about a day.

Under the surface which is made of silicate rock and ice is gigantic ocean of liquid water. It is liquid because of pressure and the friction which causes its temperature to rise.
This is why astronomers think that there could be life.
There are some missions planned, one of them is very interesting and it requires some robot to land on Europa and by heating to melt down through the ice crust towards the ocean. The heat would be made by radioactive fuel.
This thing would have to be very well sterilized so it wont find its own bacteria in the ocean. Hydrobot (on the right) would be dropped there and then it would collect samples and analyze them right in the ocean.

The volume of the ocean is more than twice as much as on Earth and it may be 100 km deep.

Because of enormous tides made by Jupiter, there are water plumes of water vapor which are 200 km high. Those plumes may carry about 7,000 kg/s of material.

Europa has atmosphere but it is not very thick with pressure of 0.1 micro pascal. This atmosphere is made by ionizing radiation hitting the ground and leaving some free atoms which than become the part of atmosphere. Part of the oxygen in atmosphere is made by process called radiolysis.

To date there were already couple of missions which saw Europa from close distance, while yes, we can see Europa even from Earth because when its whole surface turned to us is lighted its apparent magnitude is 5.27 which is pretty good.

First picture taken from close distance was this one on the left. It’s Pioneer 10s picture.
Also Pioneer 11 saw him year later (1974) and after this Voyager 1 and 2 took much better pictures. First satellite to orbit Jupiter was Galileo which was working for 8 years and then it’s course was changed towards Jupiter’s atmosphere.

For now there are planned some missions that would again orbit Jupiter and collect data about its moons especially Europa because of the ocean.
For direct studying of Europa there is planned mission called Europa clipper, which would investigate its habitability and also planned is JUICE – Jupiter Icy Moon Explorer, but this one would be mostly observing Ganymede.


All pictures are from here.

Gamma-ray bursts

today I want to look on some pretty energetic stuff. This time it will be gamma-ray bursts or GRBs.
I was inspired by episode of Crash Course which you can watch here.

GRBs are the most energetic and violent events which as far as we know can occur in our Universe.
They were discovered by accident. In the late sixties USA was trying to detect if Soviets are using nuclear tests even after Nuclear Ban Test Treaty. This treaty was signed by Soviets, UK and USA. It banned to test nuclear weapons except underground. Mostly to reduce the amount of radioctive waste released into atmosphere and to slow down nuclear progress during cold war (on the picture president Kennedy signs the treaty).

So USA was checking if there is any radiation from the atmosphere from Soviets. Indeed there was some radiation but too strange to be from nuclear bomb. It was just a short very strong glimpse of gamma burst.
Soon it was clear that it comes from space but noone was sure what is its source. All of those bursts were far too short so before any telescope turned to the source they disapeared.
Until 1991 when Compton Gamma Ray Observatory was launched practically no progress was made. CGRO was fast enough to rotate when some GRB occured and then it sent coordinates to telescopes on Earth which found out that the sources of GRBs are billions of light years away! This was such a breakthrough because those events was found out gammarayburstenergies2a.gifthat have to be extremely powerful.
But nothing so powerful exists so what they came up with was that when supernova (or hypernova) explodes the energy is lensed in two beams opposite to each other.
This is one type of GRB, the more studied. As you can see on the picture GRBs are only visible if they are pointed toward you which is much smaller fraction of those which actually occur.
The other type is long GRB, those make up of 30% of all GRBs and they are created by merging of two massive objects like two neutron stars or neutron star and black hole.

GRBs are really dangerous. The energy they emit is so high (for example the energy GRB can equal to energy of Sun, released in seconds) that if one of them in Milky Way would be pointed right towards us it would definitely cause mass extinction, like really large one.
Luckily the probability of such event is so low that we will most likely be killed by something else.

While we can see about one GRB per day they happen about once 100,000-1,000,000 years in galaxy of Milky Way’s size. The most distance one was detected to be 30,000,000,000 light years away.


WTF? A conspiracy? 3) Van Allen radiation belt

one of arguments by hoaxers is that astronauts would never be able to pass Van Allen radiation belts.

First of all, what are the radiation belts.
Those are belts around whole planet created by interaction of Earth`s magnetosphere and solar wind.
Solar wind is flow of energetic particles from Sun. Those belts were first discovered by James Van Allen.
There are two parts of them. Outer belt which is less dangerous and inner belt where is much more charged particles and especially protons.
It was also proved that there is antimatter in those belts but it is just such a low amount that we would not be able to use it anyway.

Well so hoaxers made up that if human being tried to cross this radiation belt it would kill him. The problem is that it would not, if he went fast enough.

Van Allen`s radiation belts are not stationary which means that there are days when there is more radiation and days when there is less.
Quess when NASA wanted Apollo to fly, huh?
So Apollo 11 went in angle of 30° from equator where the concetration of charged particles was smallest.
The fatal dose of radiation is 1000 rads while the astronauts got from the most dangerous part about 26 rads, which they survived.
This site more deeply explains it.
Most of the charged particles would not be even able to penetrate the space craft. Those which would, would give astronauts a dose about 50mSv. Which is something but it even counts with “higher” number of protons to not going through but all of them shooting the body.
The dosimeters you can check here.


Why won´t we visit Mars?

Hi guys!
Because yesterday I saw movie Interstellar I have got an idea! Lets write something about space traveling!

Btw. Interstellar is really awesome movie and I highly recommend you to watch. There are some things that does not make any sense but whole movie is really great, and long (165 minutes).

So, there are some plans to visit Mars (with people), maybe you already heard about it.
First of all: Why should we visit it?
1) Prestige, country which would create this expedition would gain prestige, like with Apollo 11 mission
2) Science, we would gain lot of informations about Mars if people would stay there
Second of all: What are the problems?
1) Radiation, because astronauts would not have ozon layer like on ISS they would get huge amount of radiation from Sun. We would need probably some amazing material or faster plane.
2) Energy, Mars is far away.. which means that you need lot of energy. Yes satelites can get there with solar panels but humans would get too much radiation from that time in space.
3) Food, for half a year there needs to be lot of food for those people.

As you can see problem 1,3 could be solved by faster plane… which would probably rise problem 2.. we would not be able to store so much energy considered to reasonable amount of space.
For me, I would quess that It will take more than 70 years to get somebody to another planet.

If you can come up with another idea, feel free to share it down below in the comments.