## Photon have mass?

• Photon is an elementary and stable particle.
• It have no mass at rest.
• It have no charge.
• In empty space, it travel at the speed of light(c)
It's energy and momentum is related by below equation:

E=PC

Where-  E= energy of photon
P= magnitude of the momentum
C= speed of the light

The equation foe relativistic relation is given blow:

A photon have dual nature: Wave and Particle. A photon is described by wave vector in quantum field theory.
The energy and momentum of a photon depends only on its frequency or inversely, its wavelength

E=hv =hc/λ
P=h/λ

So, Photon have no mass but it have momentum.

Photon have also a different quantity called spin angular momentum which not depends on frequency. The magnitude of the spin is root2h and the component measured along the direction of motion, it's helicity, must be +or-h. There are two possible helicity which called right handed and left handed.

Many people say that photon have mass. If a photon did have mass then it would not move at the speed of light in vacume. It would slower than c and depends on its frequency and also coulomb's law would be modified and the electromagnetic field would have an extra physical digree of freedom.

The Maxwell theory predicts that the energy of light wave depends on its intensity, not on its frequency. But after some time, many experiment show that energy of light wave depends only on its frequency, not on its intensity. After that time, investigation of blackbody, according to Einstein thge energy of any system that absorbs or emits electromagnetic radiation is an integer multiple of an energy quantum:

E=hv

After that Einstein received the Nobel prize in physics in 1921.

## How Many Dimensions Do We Live In ?

One of the most confusing, complex and debated question is how many dimensions do we live in ? At first, our common sense tells us that we live in 3 dimensional world as we perceive 3 dimensional things easily but is it some illusions ? Is there some extra dimension that is unknowingly being used to perceive 3 dimensional world ? how many dimensions are there exactly ?
Think about this for a moment, imagine you yourself as a single point and there’s nothing else other than that. As you being a single point, you won’t be able to see yourself ever and no one else could as there’s absolutely nothing else. Imagine there is a line and you are a point on that line. Whether you look to left or right, you would only see single point but never actually a whole line. That’s you being in single dimensional world.

Now, consider there’s a 2 dimensional plane and you as a point part of it. You won’t be able see yourself but from other points you could be seen. On higher level it won’t be possible for anyone being part of that 2 dimensional plane and seeing it completely. To see 2 dimensional plane viewer has to view it from outside of plane. Since, the plane is 2D, to see it completely you need to have a vision from 3rd dimension. For example, say there’s a piece of paper which has rectangle drawn on it. Stick that paper on the wall and try to see drawn rectangle from top view or side view. You always will see a line and not the whole rectangle. But if you see rectangle from front view you will see whole rectangle.
In short, in order to perceive 1 dimensional world, we need access to 2nd dimension and to see 2 dimensional world, we need access to 3rd dimension. So if you want to see nth dimension, you would need vision of n+1th dimension. As we know we can perceive 3 dimensional things, there has to be 4th dimension and this 4th dimension is time !
If you ask us how many dimensions do we live in ? our answer would be we live in 4 dimensional universe with 3 spatial and 1 temporal dimension. But how come time being a 4th dimension ? Imagine you are looking at car that is not moving. You can not be sure weather it is a 2D picture of car or a actual car unless it moves with reference to some point. Its a movement that allows us to infer that our world really does have 3-dimensions, we can move around and we see things moving in a way that clearly must be representative of a 3D world.
Now think about this: What is it that allows movement to be perceived in the first place? Of course, it is time, because movement doesn’t make sense to us without time. So, in a sense, we do experience a 3D world using our vision, but not directly a world with 3 spatial dimensions, instead we perceive directly a world with 2 spatial and 1 temporal dimension which allows us to infer the existence of the third spatial dimension.

## The Great Attractor: Gravity Anomaly Pulling Us Us Towards It At 600Kms/s

There’s something out there known as The Great Attractor SO massive that it’s pulling on every object within hundreds of millions of light years. But we can’t see it! But Why ? No, it’s not a black hole if you are thinking about it.
There’s a direct relation between mass of an object and gravitation pull produced because of that mass. So, more the massive object (not huge always) , more the gravitational pull. Simplest example is black hole who has huge mass concentrated in tiny little size but has gravitation pull so strong that even light can’t escape from it.
The Great Attractor – an object with such a ultra huge mass that it’s pulling on everybody withing range of hundreds of millions of light years. We cannot see it as our own galaxy’s plane is blocking the radiations coming from that massive body. Scary thing about this is that it’s only 200 million light years away !

Initially, scientists thought that this pull is because of Virgo Supercluster which we are part of but problem was, this super cluster’s mass is not sufficient enough to drag us there at such enormous speed. That implied there had to be something even BIGGER than the super cluster.
Currently, there’s one super cluster known as Shapley Supercluster which is millions of times massive than our milky way galaxy and compared to virgo super cluster, it’s like small peanut to burj al (dubai’s tallest skyscraper). Scientists believe that it’s the most massive thing in the entire observable universe.
So question is, who is giving us the Peculiar velocity (who is pulling us) . This Shapley supercluster ? is it great attractor or there’s something else which is currently hidden to us ? Fact is we don’t know yet !

## Time Runs Slower In Space – The Time Dilation Effect

Having fun with your friends but time seems to fly so fast. You are close to complete a level in a game but suddenly the timer starts moving super-fast. But in some cases you think time is not passing by. Best example would be when you sit for a lecture in school or college but time does not pass by.
We all know the rate at which time passes is constant for all of us. So whether it is a lecture or a game you are playing the time moves at the same rate. But certainly we don’t feel it that way.
Suppose you are shown five boxes from a distance one after the other and from the five boxes one box is shown to be moving towards you. One would certainly feel the box that was coming to you appeared to be there for more time than the other four boxes. But it was not so. The time for which each individual box that was shown to you was the same that the box which was coming towards you appeared to be. This is nothing but the time dilation effect in psychology.
Time Runs Slower In Space ?
Einstein’s theory of relativity also shows that faster something travels the slower time appears to move. Suppose you are on earth holding a clock and a friend of yours is in a space rocket which is passing by at nearly 150000 miles per second and she also has a watch with her. If supposing you are able to see your friends watch you would notice that the time moving in her watch is very slow as compared to yours.
To test this time dilation effect various experiments were conducted where atomic clocks were used on airplanes going around the world. The timings of these clocks were compared to the time of clocks kept at a national observatory in Washington, DC. And what Einstein has thought it was actually found the clocks in the airplane seemed to move slower.
Scientists have found various mathematical or space travel techniques to prove this time dilation effect. It is found that if a person travels for a year at 95% the speed of light, he would age one year, but people on earth would age 3.2 years. And even if the person travels at 50% the speed of light, people on earth would age 1.15 years. This effect cannot only be studied through space travel. But now scientist have also found a way to prove the same thing on earth in a lab.

## What If You Were Born In Space ?

Imagine someone asked you which is your birthplace? And you are like I’m born in space. Doesn’t this sound interesting?
First let us look at how many people are already there in space. The first person who went to outer space 52 years ago, after that more than 500 people have left the earth and have gone as far as the moon. So from the past few years there has been a continuous uninterrupted presence of humans living in space. But all these people who have gone out or are present on earth are born on this planet earth.
But what if someone is born in space? How suited is our biology for the outer space we were born into? But where do we consider this outer space to be? Outer space is about one hundred thousand meters above your head.
We all believe that the people who are in space are floating around because there is no gravity. But this is a very big misconception as there is plenty of gravity as it is on earth. They are not floating, rather they are just falling due to the orbital speed. An orbital speed is a speed which is so fast that even while falling you don’t, because the earth literally curves away from you as fast as you fall towards it. So we cannot say that there is no gravity in space but we can say that it is a zero g environment where g is acceleration.
So if the gravity is pretty much the same as earth how would a human look like if they were born in space? To understand how humans would look, it would require us to understand first what effect weightlessness has on the human body. Even mere hugging each other in space is difficult but a recent invention called the ‘2-suit’ might make it easier. This invention provides effortless intimacy in a weightless environment.
A baby inside mothers needs the development of the vestibular system. Canals in the inner ear that uses the flow of fluid to determine movement and balance. In a zero g environment i.e. Space the fluid required would just float around and this can lead to motion sickness, visual illusions and disorientation. This was experimented with the help of pregnant rats. Pregnant rats taken to space when gave birth to babies struggled with directions. Vestibular fluid is not the only fluid that would affect the babies born in space, but there are other fluids as well, which would get affected by a zero-g environment. So this zero-g environment gives the babies a puffy face due to the floating fluids and all of those fluid pressure on your face can also affect the vision.
These are not the only side effects of space. Even astronauts who had long flights and returned back to earth were tested. Almost everyone had visual problems. An astronaut can even lose about 22% of their total blood volume while in space. Also the radiation from the sun and the rest of the universe can be dangerous for the human body and we are still not sure how to safeguard ourselves from these radiations.

As for the shape of the human body, full grown astronauts in orbit, no longer pressed down by earth typical gravitational force experience spinal expansion as much as 3 percent before they come back to earth. Even a person as tall as 6 feet can go to space and return as tall as 6 feet 2 inches. In a weightless environment you don’t need much muscle strength to move around, so your muscle strength in space to weaken. All of these reasons sound scary to live in space.
We all understood that these problems affect the adults in space and pretty much the same way it would affect a developing baby in space. So a baby born in space would might look like this because of the active forces required for developing healthy bone structure would just not be there.
Many studies have been done on this topic and some are even planned for the future as we don’t even know that a healthy fetus can develop in space or even conception can even occur in space. So let’s wait and see if all this can happen in future.

### Albert Einstein and the Theory of Relativity

Elbert Einstein gives his Special Theory of Relativity in 1905 and his General Theory of Relativity in 1915. The first showed that Newton's three laws of motion were only Approximately correct,breaking down when velocities approached that of light. The second showed that Newton's Law of Gravitation was also only approximately correct, breaking down in the presence of very strong gravitational fields

## Newton vs. Einstein: Albert's Turn to Kick Butt

Here, I only summarize the differences between Newton's theory of gravitation and the theory of gravitation implied by the General Theory of Relativity. They make essentially identical predictions as long as the strength of the gravitational field is weak, which is our usual experience. However, there are three crucial predictions, where the two theories diverge, and thus can be tested with careful experiments.

 Precession of Perihelion
1. The orientation of Mercury's orbit is found to precess in space over time, as indicated in the adjacent figure (the magnitude of the effect is greatly exaggerated in this figure). This is commonly called the "precession of the perihelion", because it causes the position of the perihelion to move. Only part of this can be accounted for by perturbations in Newton's theory. There is an extra 43 seconds of arc per century in this precession that is predicted by the Theory of General Relativity and observed to occur (a second of arc is 1/3600 of an angular degree). This effect is extremely small, but the measurements are very precise and can detect such small effects very well.

2. Einstein's theory predicts that the direction of light propagation should be changed in a gravitational field, contrary to the Newtonian predictions. Precise observations indicate that Einstein is right, both about the effect and its magnitude. A striking consequence is gravitational lensing.

3. His General Theory of Relativity predicts that light coming from a strong gravitational field should have its wavelength shifted to larger values (what astronomers call a "red shift"), again contrary to Newton's theory. Once again, detailed observations indicate such a red shift, and that its magnitude is correctly given by Einstein's theory.

4. The electromagnetic field can have wave in it that carry energy and that we call light. Likewise, the gravitational field can have waves that carry energy and are called gravitational waves. These may be thought of as ripples in the curvature of space-time that travel at the speed of light.

Just as accelerating charges can emit electromagnetic waves, accelerating masses can emit gravitational waves. However, gravitational waves are difficult to detect because they are very weak and no conclusive evidence has yet been reported for their direct observation. They have been observed indirectly in the binary pulsar. Because the arrival time of pulses from the pulsar can be measured very precisely, it can be determined that the period of the binary system is gradually decreasing. It is found that the rate of period change (about 75 millionths of a second each year) is what would be expected for energy being lost to gravitational radiation, as predicted by the Theory of General Relativity.

## Why fire burns upward?

• We all know that fire burns upward. But why?
• We can understand this with a candle example.
• When we burn a candle, then we saw that fire burns upward. In this process, base of flame not so hot than upper flame. So atom arround of upper flame get very hot and its density will decrease atoms arround of base of the flame get low heat and its density will increase. So, there is work a force due to difference in density, which apply opposite to the gravitational force. It is called Buyonacy Force.
• The color of the flame is spooky blue light.
• So, fire burns upward due to buoyancy force.

## How fire Burns On The Earth?

• Basically, Fire needs three requirements. In the nature, if three requirements are fulfilled, then fire is possible. Three requirements are heat, fuel and oxygen.

• Oxygen only helps to burn fire. Oxygen helps to combine with fuel.
• If any fuel gets heated in the presence of oxygen then atoms of fuels vibrates and after then if we continue to give then atoms doing dance and after that in the presence of the more heat bond of atoms are broken and then fuel reduce heat and light. This process is called Fire.
• Fire color is orange and yellow.

• For example, we took a wood. If we give heat to a wood, then atoms of wood are broke and fire will burn.
• In wood C, H, O and some other elements are present.
• When wood burns then it reduces C and H and happened their oxidation.
• C change in CO2 due to oxidation and H change in H2O due to oxidation. We all know H2O. It is called water vapor.
• So this process is called burns a fire.

For more information view our video on YouTube.

## 1. Autonomous Robots

We all know that #robots make easy our lives and help us for any hard work. But think a little about smart robots who can think independently. A robot, who can think smart and great new idea and felt everything and can give emotions, is called Autonomous Robots.
Scientists are working on this type robots. Many robots have built for army mission, but #scientists try to make a helper robot which can help people in their daily life.
Think, When you wake up, then Robot offers you coffee and if you have any problem and you are saying then robot ask you for telling your problem and then the robot will give perfect solution and try to happy you. This is cool.

## 2. Screenless Display

This is an amazing and advanced #Technology to display anything. It has 3d images and HD revolution images. It is automatically revolution entertainment. Hologram is the most common example for visual images on Screenless Display.

## 3. Wireless Electricity

You will think that this is impossible, but it is possible.
You need two coils, a transmitter coil and a receiver coil. AN alternating #current in the transmitter coil generates a magnetic field which includes a voltage in the receiver coil. This voltage can be used to power a mobile device or charge a battery.
It is very amazing. It is possible by MIT. It is transforming  of electromagnetic pulse. So now you understand it.

## 4. Invisibility

When a person sees an object, the seeing is made possible by the effect of light bouncing off that object and back to your eyes. Different surfaces reflect light in different ways, depending on how they are shaped at the microscopic level. So if we designed some things in such a way that they cancel out the effect of these things that allow you the to see things, then your things become is invisible.

## 5. Flying Cars

It is a dream, but near 2050 it is becoming in reality. Scientists are trying  to make a #Flying car.
In many fiction film flying cars predict. It will very safe and cool. No traffic problem and no more need of road.

For more technology and Top 10 Science Fact view our video on YouTube.
https://www.youtube.com/watch?v=do0HxBUB_ZM

### 1. What is dark energy and dark matter?

Scientist calculates that, In the universe 73% dark energy, 23% dark matter and 4% normal matter. Now, you know that dark energy and dark matter both are very important because they have almost 96%. When scientist use the telescope for seeing in the universe, then they feel something which invisible (something dark) and then they called it 'Dark Matter'.

Now we talk about dark energy. Dark energy is the biggest mystery of the universe. It is everywhere. It will determine the fate of our universe. And we still not idea what it is.

So what is existence of dark energy and dark matter. And why it is invisible?

### 2. What extra dimensions are possible?

We all know that there are three dimensions possible. When we describe the size of an object, or of a space like a room, we use three numbers; the height, the width and the depth. The height, width and depth of a room are numbers that can vary independently from one another. That is one way to see that space is three dimensional.

When mathematicians or physicists talk about dimensions, they mean the number of independent coordinates needed to specify any point in a given space. In presently there are three dimensions (x, y, z,).The gravitational force between two planets and the electrostatic force between two electric charges were both observed to vary as the inverse square  of the distance between the two objects. So if you twice as far away, the force will only be one fourth as strong. But the numbers of the coordinates in a mathematical equation are easy to increase on paper. When the gravitational and electrostatic equations are solved in a space with D dimensions, then the force varies with distance. This gives physicists an interesting way to do fine measurements of the numbers of the dimensions of space. And time will be an extra dimension.

So, what is possible? if this possible then howmany dimensions?And what mean of dimensions?

### 5. How did the universe begin?

It is the biggest question. Many scientists try to solve this mystery but what is real? it nobody know.
Like, Stephen Hawking give many theories and a big bang model come. So many models come, but no any one knows about beginning the universe.

### 6. How is balance universe?

Everyone believes in the balance of the world. But we don't know that why are we alive and which thing is supporting us. Every man is born but die. The universe is balanced. But we did not know that what is our existence? The nature has many thing and balanced, but what is the reason that we alive?

So,Why we alive and balanced and after some time die? And where we gone?

### 7.What is Gravity?

So, Where does gravity come from?And what cause gravity?

### 8. What is the lifetime of the proton and how do we understand?

We know that every atom has a Nucleon and every nucleon have proton and neutron. Proton has a positive charge and mass, but neutron is neutral. But due to proton decay, one day destroy the whole molecule. But,in real this not possible.

So, Why proton is not losing their charge and energy and don't destroy?