Relativity Law ( Albert Einstein)

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels.
Two objects exert a force of attraction on one another known as "gravity." Sir Isaac Newton quantified the gravity between two objects when he formulated his three laws of motion.

1. Welcome to Our Presentation

2. Topic: Relativity

3. Group Members Name ID Ariful Islam Arif 162-15-7885 Mohammed Mahmudul Hasan 162-15-7760 Pritam chandra shil 162-15-7882 Aklasur rahman robin 162-15-7708 Farok hossain 162-15-7937 Mehedi hasan 162-15-7804 Md Rakibul hasan 162-15-7735 Md .Abu- Sufian Abdullah 162-15-7869

4. Relativity Theory By : Albert Einstein

5. About Albert Einstein

6. Einstein was born in:- 14 March 1879 At:- Wurttemberg , Germany. And died on:- 18 A pril 1955(aged 76) At :- Princeton , New jersey , USA

7. What is relativity?? The way that anything except light moves through time and space depends on the position and movement of someone who is watching.

8. Space & Time

9. Theory of relativity Albert Einstein’s theory of relativity is actually 2 separate theories : His special theory of relativity postulated in the 1905 paper, the electrodynamics of moving bodies & his theory of general relativity, an expansion of the earlier theory , published as the foundation of the general theory of relativity in 1915. Einstein sought to explain situations in which N ewtonian physics might fail to deal successfully with phenomena , and in so doing proposed revolutionary changes in human concepts of time , Space an gravity.

10. Theory of Relativity Special theory of relativity General theory of relativity

11. Special theory of Relativity It is a theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of Physics are invariant in all inertial system. Special relativity is a theory of the structure of space time . It was introduced in Einstein's 1905 paper "On the Electrodynamics of Moving Bodies."

12. Special theory of Relativity: There are two postulates of special relativity. The Relativity Postulate : The laws of physics are the same in every inertial reference frame. The Speed of light Postulate : The speed of light in vacuum , measured in any inertial reference frame , always has the same value.

13. The Reference frame A Reference frame is the point of view , from which we observe an object. A Reference frame is the observer it self , as the velocity & acceleration are common in Both. E.g.:- Let’s us see how the observation changes , with the change in observer or we can say The Reference Frame. A car moving on the Earth. A bomb dropped from a Rocket.

14. CONSEQUENCE OF RELATIVITY The Major Consequences To This Theory are:- Length Contraction Mass Expansion Time Dilation

15. LENGTH CONTRACTION “ It is the phenomenon of shortening of Length which is the relative motion with respect to the observer” Thus the length of a body appearing to an observer depends upon the relative velocity of the body with respect to the observer. And the Proper Length of a body can known by measuring it’s length when it is at rest w.r.t the observer. It is given by  

16. MASS EXPANSION, E=M   Mass–energy equivalence: E = m , energy and mass are equivalent and transmutable.  

17. TIME DILATION “ Time dilation is the phenomenon of showing down of a clock as determined by an observer who is in relative motion with the clock” ** As it is an relative thus the Extent of Dilation depends on upon the relative Velocity of the clock w.r.t the observer. It is an very important consequence of the special theory of Relativity . And given by : t =  

18. General Theory of Relativity..

19. What is General Relativity? Albert Einstein’s general theory of relativity is one of the towering achievements of 20 th century Physics, p ublished in 1915. It is a generalization of special relativity to include gravity(based on the principle of equivalence). The basis of general relativity describes how mass and space are related to each other and states that matter can bend and warp the fabric of space and time due to the effects of gravity.

20. Einstein proposed that objects such as the sun and the earth change this geometry . In the presence of matter and energy it can evolve , stretch and warp , forming ridges ,mountains and valleys that cause bodies moving through it to zigzag and curve . So although earth appears to be pulled towards the sun by gravity , there is no such force . It is simply the geometry of space-time around the sun telling earth how to move.

21. The general theory of relativity has far-reaching consequences . It not only explains the motion of the planets . It can also describe the history and expansion of the universe, the Physics of black holes and the bending of light from distance stars and galaxies.

22. Major application of General Relativity Newtonian Physics predict an elliptical orbit of a planet , with the sun in one of the focal points.

23. For the same situation , Einstein’s theory predicts a slightly different orbit : not an ellipse , but a kind of rosette . As mercury orbits around the sun , the two points of each orbit closest to the sun and furthest away from it,(in astronomical lingo : perihelion & aphelion) should every-so-slightly shift from one orbit to the next . The following figure show an exaggerated version of movement:

24. In the solar system, where there’s more than one planet orbiting the sun, the situation is a bit more complicated . There, the mutual gravitational pull of the planets on each other leads to a slight shift of perihelion and aphelion points , even without Einstein’s results . However for Mercury , where the relativistic effect should be strongest , the shift that we observe is slightly larger than expected . Even when the influence of all the other planets taken into account , a slight extra contribution is left.

25. Impacts of relativity GPS (Global positioning system):In order for your car's GPS navigation to function as accurately as it does, satellites have to take relativistic effects into account. This is because even though satellites aren't moving at anything close to the speed of light, they are still going pretty fast. The satellites are also sending signals to ground stations on Earth. These stations (and the GPS unit in your car) are all experiencing higher accelerations due to gravity than the satellites in orbit. if no relativistic effects were accounted for, a GPS unit that tells you it's a half mile (0.8 km) to the next gas station would be 5 miles (8 km) off after only one day .

26. Color of Gold : Gold is a heavy atom, so the inner electrons are moving fast enough that the relativistic mass increase is significant, as well as the length contraction. As a result, the electrons are spinning around the nucleus in shorter paths, with more momentum. Electrons in the inner orbitals carry energy that is closer to the energy of outer electrons, and the wavelengths that get absorbed and reflected are longer .

27. Longer wavelengths of light mean that some of the visible light that would usually just be reflected gets absorbed, and that light is in the blue end of the spectrum. White light is a mix of all the colors of the rainbow, but in gold's case, when light gets absorbed and re-emitted the wavelengths are usually longer. That means the mix of light waves we see tends to have less blue and violet in it. This makes gold appear yellowish in color since yellow, orange and red light is a longer wavelength than blue.

28. Old TVs: Just a few years ago most televisions and monitors had cathode ray tube screens. A cathode ray tube works by firing electrons at a phosphor surface with a big magnet. Each electron makes a lighted pixel when it hits the back of the screen. The electrons fired out to make the picture move at up to 30 percent the speed of light. Relativistic effects are noticeable, and when manufacturers shaped the magnets, they had to take those effects into account.

29. Electromagnets : Magnetism is a relativistic effect . Only some metals are naturally magnetic, like iron, for example. That being said, it is possible to create a magnet out of any metal by turning it into a coil of wire and running an electric current through it. These electrified metals have a strange property: they only magnetically affect objects that are moving and they don't have any effect on stationary objects. This is an electromagnet, and it is thanks to special relativity that this phenomenon is possible.

30. Without the relativity theory, We would not have GPS on our phones and in our cars. Our understanding of the Big Bang and black holes would also be different.

31. Thank You!!!