Move back and forth in time( TIME DILATION)

Time dilation leads us to time travel!! Sounds great, but kinda weird to explain. Your concept of relative speeds doesn’t work here.

If you and superman are flying with the same speed, then with respect to you, the superman is at rest. This isn’t the case with light, as long as your speed is less than light( though your speed is so close to light), the speed of light doesn’t change with respect to you.

If speed isn’t changing with respect to you, though you are moving, then what is changing? Well… The time is changing. So, this is the key for time travel.

Have you watched the movie “Interstellar”? Yeah you must. When the hero returns to his daughter from another planet probably in other solar system, his daughter becomes more than 90 years old( that is much older than her father). This is time dilation, because of his journey through wormhole.

You could do a flyby of a nearby star and return to Earth at nearly the speed of light, and a few years would pass on Earth while possibly only a few weeks or months would pass for you, depending on how fast you were going and how far away the star was.

Few of my recent articles are related to this one.  RELATIVITY (all about the Einstein’s special and general relativity) and the previous one Stars ( which proves that, even light with such great speed takes “Time” to reach us;)

There is another extension to this article, can you guess one?






Here’s the third and the last reblog of my own age old articles, to those who are new, I have stared this kinda reblog thing to make my blog active in my exams time. Here we go from next Wednesday, there will be regular articles.😊😊

Of the many philosophical assumptions in physics about the nature of reality, none is more mysterious than the existence of time. Unlike space, time does not have any of our five senses assigned to it. Our primary sensory mechanism, sight, creates a 3D world around us. Even in the absence of vision, hearing can place point […]


what’s a leap second?

The time it takes for earth to rotate around the sun actually isn’t consistent, it differs few fractions of seconds. This is the reason why we add leap seconds once in a while. Recently on june 30th 2015 we added a new second.

Time keeping!!

So, we created the time. We can’t actually sense time with our senses. Learn more about the nature of time right here Nature of time. So, Before we talk about time keeping which is so long indeed, let’s quickly see

Since ages we humans are trying to make time more and more accurate. So let’s get to the history, in 3500BCE Egyptians started measuring time using sun. By placing a tall stick or something, which casts shadow in a particular place according to the suns position. But this isn’t accurate because this doesn’t work on a cloudy day and this changes the durations according to the season change.

So, to overcome this problem “Mechanical clocks” were built. As the time is calculated based on a relative change, these clocks also work on the same principle “Measuring time using a repeated process”. The first in that kind were Water clocks, which measure time according to the volume of water dropped at a constant rate in a marked container. And these mechanical clocks became sophisticated and we started using notched wheels for the constant movement but there was a problem in regulating the speed of the wheel. Now here come the concept of Pendulum. Galileo in 1600 studied the motion of a pendulum, which states that no matter what the mass of the pendulum is, it makes back and forth motion rate constant depending on the length of the pendulum. And this concept was used to build a pendulum clock.

These pendulum clocks were great, but these clocks were a problem to the sailors who often were on the moving ships. To solve this problem John Harrison invented a pocket clock which works on a spring mechanism.

After a long gap, in 1960 Quartz clocks were invented. Quartz crystal is a Peizo electric material, which gives out electricity by applying pressure and vice versa. Learn more about working of Quartz watches on my previous post How a Quartz watch works?. It changes only 15 seconds per month which is pretty much accurate than the precious clocks.

But we need still more accuracy, we depend on time more and more these days, for example the stock market.

For still more accuracy we invented Atomic clocks. Previously a second =1/32,000,000 of an year according to the rotation of the Earth. Scientists felt that, even this is not accurate, the rotation of the earth in its orbit also varies every year due to many factors like moon.

So, to get the most accurate time, the second was defined based on the INTRINSIC property of CESIUM. In these atomic clocks the Cesium is used to tune the waves to a specific frequency. Which has 9,192,631,770 Hz frequency when ever the clock hits that number it counts one SECOND..

For still more accuracy scientists invented Optical clocks which will not show even a second difference for 13 billion years!!!

So let me know your feed back…


Of the many philosophical assumptions in physics about the nature of reality, none is more mysterious than the existence of time. Unlike space, time does not have any of our five senses assigned to it. Our primary sensory mechanism, sight, creates a 3D world around us. Even in the absence of vision, hearing can place point sources in a 3D space. We have no built-in mechanism to perceive or sense time.

So what makes us sense time? 

Time is sensed through change. We can best sense objects and movements at scales comparable to our body dimensions and speed. We can clearly see a person running, but not a bullet coming at us. We can appreciate the difference in size between an adult and a child, but not between two celestial objects or micro-organisms.  Our sense of time is modulated by our life expectancy.

Time is Relative.

 For suppose, if we lived forever, would we have a sense of time?  If we did not have a sense of time, would that mean there was no time? Does time have an existence independent of our minds? More to our purpose in this book, would it be possible to do physics without a notion of time? Physics, as we know it today, (e.g., Newton’s laws of motion and the special theory of relativity) has time figuring prominently as an essential ingredient. A physics with no explicit time was attempted by Julian Barbour (in The End of Time), which shows that time is not essential. Time, however, makes it far more convenient to do physics.

Do animals have a sense of time? It is unlikely that they are conscious of their death. So, by our conjecture, they should not have a sense of time.
If you grew up on an island, without contact with other human beings, would you have a sense of time? It seems obvious that you would not have a language in the conventional sense of the word. Some philosophers believe that you would not even have any thoughts at all. But does the sense of time come before or after thoughts?

Time is unreal assumption like Mathematics we use. But that’s an extremely convenient tool, which we use to solve many problems in Physical Sciences.

This is the topic where we get more questions than answers. This is a never ending process. All of it cannot be discussed in a single post. This is just a part of it. Expect still more posts on Time.

I hope you like this above information about the Nature of Time.  All that information is taken from bunch of different sources and if you are interested in learning more about TIME, check out the PDF of “A BRIEF HISTORY OF TIME BY STEPHEN HAWKING”