Skip to main content

TIME DILATION



TIME DILATION: A review of The Twin Paradox


“Time and space are modes by which we think and not conditions in which we live”
-Albert Einstein

Time measurement began with the invention of Sundials as early as 1500 B.C. Till now humans have defined time by a set of rules which seemed convenient to them. Several Concepts have been surrounding this physical quantity since then. We shall take a look at one of those concepts named “TIME DILATION”.

 
Time dilation is a famous phenomenon featured in various sci-fi movies including the popular one, Interstellar. It may be defined as the difference in the elapsed time between two clocks because they have a relative velocity between them.

A simple thought experiment which can validate this is the twin paradox which shows that time passes at relative speeds when relative velocities are involved. Here, two twins (X and Y) are taken - Y flies in space at nearly the speed of light (90%) to an object 9 light-years away while X remains on earth. Theoretically, it is seen that, when Y returns from space, he is aged only by a few years while X is aged by a large number of years.
 The example can be explained  as follows:


Let us assume that the time needed to bring the spaceship back towards earth is negligible. Y argues that time moves slowly for X while X states the opposite. So who is actually correct?
X has 0 acceleration and hence remains in the same inertial frame.
Yon, the other hand has a non-zero proper acceleration as he makes a turn and decelerates to a stop. Thus he has two inertial frames of references, one while moving away from earth and the other while moving towards it. Time dilation should be used in a single frame of reference. Hence, Y’s result is wrong.
Thus, here there are three segments to the process:
1)       X and Y are at the origin.
2)       Y is nearly 9 light-years away (Measured from X’s frame)
3)       Y returns back to origin.

According to the calculations of X,


we use a gamma factor which comes out to be 1/0.436. (Gamma)

 For the segment 2,
 time passed for X = 9/0.9=10yrs
                            
time passed for Y = 10x(Gamma) =4.36 years
For segment 2 to 3 their time ticks by another 10 and 4.36 yrs respectively.

Thus when they are back at the origin, X has aged 20 yrs but Y is 8.72 years. This will be the correct answer as he calculates from a single inertial frame of reference. Thus, Y’s assumptions will be wrong as he is using two frames of reference for his calculations (as stated earlier).

An example of this effect was also studied by NASA on the twin astronauts Scott Kelly and Mark Kelly. Scott Kelly stated after returning from space, "I came back from space younger than my twin."

Albert Einstein’s theory of Special Relativity has been verified with unprecedented accuracy. Experiments with the help of the particle accelerator in Germany has also proved the dilation effect with great accuracy.



 
Space and time are still one of the most intriguing and complex problems faced in the field of science. This paradox is one of the different attempts taken to understand the mysterious nature of the physical quantity “TIME”.

Saptasya Mukhopadhyay
Ritwick Banerjea
Department of Chemical Engineering (HIT-K).

Sources -
1)       A Brief History of Time ( S. Hawking)
2)       einstein-online.info
3)       Youtube videos
4)       scientificamerican.com
5)       www.nasa.gov.in

Comments

Post a Comment

Popular posts from this blog

NEUROIMAGING IN IDENTIFYING DISORDERS

NEUROIMAGING IN IDENTIFYING DISORDERS Neuroimaging deals with the in vivo applications of various techniques to illustrate and study the structural & functional characteristics of the nervous system. Neuroimaging can be classified into two categories: • Structural neuroimaging, which involves the imaging of the structure of the nervous system and the diagnosis of intracranial injuries and tumours. • Functional imaging, which involves the study and diagnosis of metabolic diseases and cognitive research. The most widely used techniques involved in the process of neuroimaging are: 1. Computed Tomography (CT) or Computed Axial Tomography (CAT), in which X-ray images of the brain from various directions are taken and presented as cross-sections of the brain. 2. Magnetic Resonance Imaging (MRI), which uses magnetic fields and radio waves to obtain high-resolution 2D or 3D images of the brain. 3. Positron Emission Tomography (PET), which measures emissions from radioac...
3 comments
Read more

EMOTION SENSING TECHNOLOGY

Emotion is a mental state associated with the nervous system brought on by chemical changes variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or displeasure. Reading and understanding emotions can lead to wide-ranging opportunities. Emotion sensing technologies are being widely used in many applications to effectively understand the users' mood and use that information to do something productive. EMOTION SENSING TECHNOLOGIES can be used in various fields such as personal robots, driverless cars, educational software, consumer electronic devices, video games etc and is on the verge of becoming the next big thing. THE TECHNOLOGY INVOLVED: SKIN CONDUCTANCE SENSORS: Skin conductance (SC) is an index of sympathetic nervous system (SNS) activation and emotional arousal. To measure skin conductance, a small electrical potential is applied between two electrodes strapped or taped to the palmer side of the hand, and the amount of ...
2 comments
Read more

BLACK HOLE & SPACE-TIME RELATION

BLACK HOLE & SPACE-TIME RELATION                                 W e are all pretty familiar with the term  'Black   Hole' . Well, what does it really mean? Firstly, the 'Black Hole' is not black at all. It is a kind of void from which light cannot escape. According to the general theory of relativity, proposed by Sir Albert Einstein, the black hole is that region of space and time, where the gravitational attraction is so strong that nothing can escape from or through it. A huge, enormous amount of mass is concentrated over a very small volume. And, consequently, the density of the black hole becomes incredibly strong. ⮚       Formation of the 'Black Hole':  Well, so far as the creation of the black hole is concerned, it is speculated that if the centre of an enormously distributed star collapsed and, as a result, the 'SUPERNOVA EXPLOSION' occurred. The...
Post a Comment
Read more