WORMHOLES AND WHITE HOLES : A JOURNEY TO UNPROVEN THEORIES OF RELATIVITY

Wormholes and white holes: a journey to unproven theories of relativity

It has been a wonderful journey from knowing nothing to knowing something about this universe. Never thought I would dive so deep into this subject’s ocean that it’s hard to come back to shore.

We entered this decade with lots of things which we thought were impossible to prove. We got the proof that dark matter exists from the bullet nebula, proved gravitational lensing exists predicted by Einstein’s relativity and also the most important part of relativity i.e. black holes, we were successful in capturing the image of it and proving that it existed. But, there are some theories of relativity which are yet to be proved and in this blog I’ll take you all to that part of journey with bit of my assumptions and theories on them.

Wormholes:

There are only two theories of relativity that are yet to be proved, one is wormholes and the other is white holes. Wormholes as scientists describe is a shortcut in space-time fabric which can be used to travel from one universe to the other or from one place in the universe to the other place in the same universe. But for me and all other sci-fi geeks these are objects to time travel and explore a different universe. 

To explain wormholes in a simple way I’ll take an example which was shown in the movie interstellar. Consider a sheet of paper as space-time fabric and mark two points ‘a’ and ‘b’ at the two ends of the paper. As you bend the sheet, you will see that the two points are one above the other, if you take a pencil and make hole at both sides, you will get a shortcut connecting these points.

These holes are nothing but wormholes, connecting two points in the same universe or connecting one universe to the other. These have two openings or mouths of spheroidal shape connected by throat which is usually cylindrical or it can also be winded. These are highly unstable and collapse as soon as they form, to stabilize them we need exotic matter or in other words negative energy density matter which is dead opposite to the normal matter we have. We hardly know this kind of matter exists or not and even if exists it would not be sufficient to hold these wormholes. What I think is large rotating supermassive black holes (explained about these in my blog on time travelling, check out that blog to understand what these are) can act as wormholes. Rotating supermassive black holes have less dense singularity because they lose their force due to angular momentum. 

Anyways, there are still no practical evidences for us to prove that these things exist but relativity has mathematical solution that these are present and since almost everything has been proved, it would not be a surprise if this one gets right. 

The interesting thing about wormholes is, they not only connect two points but the objects travelling through them has their speed more than the speed of light. This gives us the chance of time travelling through these but as Nobel Laureate theoretical physicist, Kip Thorne suggests it is highly complicated and it somewhat breaks the laws of physics. As a sci-fi geek I would love to see this come true.

White holes:

Everyone has heard about black holes and know how fascinating they are but the most underrated and less known are white holes. I have never seen anybody show lot of interest in them. I personally find white holes a lot more amusing then black holes, because it has complete opposite characteristics of black holes. A black hole sucks everything which is near to it whereas a white hole emits everything and takes nothing in. Many physicists say that a black hole radiates itself and forms white hole. But I completely disagree with it, I feel black hole and white hole are two faces of a same coin, they have to exist at the same time. If you look closely into the nature everything exists in pair. Positive-negative, good-bad, matter-antimatter, protons-electrons, etc. But why not this?, a very fundamental question.

 A white hole can be defined as time-reversal of black hole, if you reverse everything going on around and inside of the black hole you get wh at a white hole does. As I was reading about these I found out that white hole can be an end to black hole. Everything which gets sucked into a black hole might come out of a white hole. Which is pretty similar to wormhole i.e. two points connected by a path. But a wormhole travels through space whereas in this an object falling into a black hole and coming out of a white hole would travel through time.

It would take quadrillions of times of the age of universe to come out of a white hole. We may not be able to detect them because they maybe at the other end of the black hole, like the second face of a coin. There is lot of quantum physics and correction of relativity equations going on in the research of white holes but in the end it all comes to the fact that these are hypothetical. I don’t know whether to laugh or cry because explaining all this stuff and finally saying its hypothetical is kind of joke and disappointment at the same time. It took 40 years to prove the existence of black holes, maybe we have to wait another 40 years or so to witness this.

I remember an incident of discussing about wormholes and time travelling with my room mate, where we created our own theories and were finding flaws in them. The discussion started from black holes and I still don’t remember how it escalated to these things, it started in the afternoon and ended at night. There is no count how many nights and days I have spent discussing and arguing about these stuff. At a point I was so deeply involved in it that I started dreaming about black holes and wormholes.

I can go on and on, on these topics and write about it but that would make this blog unbearable because of its complexity. So, I will stop it here and get back to dreaming about black holes.

INTRODUCTION TO STRING THEORY AND MULTI DIMENSIONS

Introduction to String Theory and Multi-dimensions

The universe as we know is very bizarre, no matter how hard we try to understand it still we miss out something or the other which is far more mysterious than the previous. From my previous blogs we tried to understand the universe in large scale i.e. stars, black holes, dark matter and dark energy, etc. In this blog we will try to understand it in smallest scale possible, going to the very depth of the it. Join me in this voyage to explore the unheard topic of the universe.

The modern physics stands on the 2 main theories which we call pillars of the modern physics. Einstein’s general and special relativity which helps us in understanding the universe in large scale ( ex; planets, stars, galaxies), about which we studied in my previous blog and the other one is quantum mechanics which helps us in understanding the universe in small scale (ex; atoms, electrons, neutrons). Over the years many physicists tried to unify these both into one, trying to find a single equation which gives us the entire understanding of the universe which we like to call “The Theory of everything”. But when we combine both the theories, physics begins to shake, rattle and in the end what we get is a nonsense equation. The immediate question which strikes us is why can’t we combine both?

When we study the universe, we either study on the large scale I.e. relativity or on the small scale of the universe i.e. quantum mechanics but we never study both at the same time. This becomes the reason for the above conflict in the physics. But the string theory solves this conflict, it unifies these both theories. So, what is string theory?

To understand string theory, we need to go back to basics, i.e. universe at the small scale. Ancient Greeks believed that universe was made up of small undividable particles called atoms. Over 2000 years everyone believed that its true, then J.J. Thompson, Rutherford, Neils Bohr, James Chadwick gave us the atomic model which gave us the constituents of the atom i.e. Protons, electrons and neutrons.

Everybody believed that this cannot be reduced further, these three were the fundamental particles. But in 1968 scientists at the Stanford linear accelerator center, making use of increased capacity of technology to study the microscopic depth of matter found out that protons and neutrons were made up of three smaller particles known as quarks. Proton consists of 2 up quarks and 1 down quark whereas neutron consists of 2 down quarks and 1 up quark. Before that in 1950 2 scientists Frederick Reines and Clyde Cown discovered fourth fundamental particle known as neutrino which is known as ghost particles. These are massless particles which have no charge; therefore, these are called as ghost particles.

Back in 1930’s physicists found another particle called muon identical to electron but is 200 times heavier than the electron. This shook the entire physics community, what we thought as fundamental particles were not the one.

Using more powerful technology physicists continued to study matter in depths by recreating the situations of big bang and reducing these particles further, to our surprise we found 4 more quarks called; charm, strange, bottom and top. Another heavier cousin of the electron called tau.

Later two other particles like neutrino were found (called muon-neutrino and tau-neutrino). These particles are produced through high energy collisions. But the story doesn’t end here, each of these particles has an antiparticle partner ( a partner with identical mass but opposite charge) for example: electron has an antiparticle called positron whose mass is same as electron but charge is +1. I bet you all are going crazy by reading this, so were the physicists after discovering all these particles. So, they found a pattern among all these particles and divided them into 3 groups which are called families. Each family consists of two of the quarks, an electron or its cousin and one of the neutrino species.

So how does this help us to understand what string theory is?  The particles we see in the above table is the ultimate level to which an atom can be reduced. If atom is a sentence, then these are the letters which further cannot be reduced or broke down.

 

But, string theory suggests that if we could examine these particles or reduce further with even more precession- precession which is beyond our current technological capacity, we will find that these particles are not point like but tiny 1- dimensional loop, like infinitely thin rubber band. Each particle consists of vibrating, oscillating filament which physicists called strings. Exciting isn’t it?

String theory says that whatever properties we observe in a particle is a reflection of how a string vibrates in various ways. Just as string in a violin and guitar have a resonant frequency at which they vibrate, the strings of the particles too vibrate at a frequency which determines the property of that particle.

Which in turn suggests that whatever we observe, every atom, every element is basically made up of fundamental vibrating strings which decide their properties, if somehow, we find the strings frequency and change it, the property of each and every particle changes. In fact, the fate of the whole universe changes. Because of this, string theory stands at top for the theory of everything. As it deals with both relativity and quantum mechanics.

If the string theory is right, the microscopic fabric of our universe is a richly intertwined multidimensional labyrinth within which the strings of the universe twist and vibrate rhythmically beating the laws of cosmos. But the mathematics of the string theory is so complicated that no one even knows the exact equations of the theory. instead physicists use approximations and even approximate equations are so complicated that they have been partially solved.

String theory completely changes our understanding of the universe, it suggests that our universe has 11 dimensions. Einstein’s relativity tells us that there are 4 dimensions that is 3 space dimensions and 1 time dimensions, then what are other 7 dimensions? How string theory changes our perspective of space and time? What other implications does string theory have?

To all these questions we will find the answers in the next blog, until then wonder about this amazing theory and our strange universe…  

SPACE-TIME: UNDERSTANDING THE TRUE NATURE OF TIME

space-time: understanding the true nature of time

In my previous blog I discussed about how Einstein’s theory of relativity changed the perspective of space and time and discussed about how space and time are not independent but they are combined as space-time continuum. It was just an introduction to the space-time concept, in this blog I will discuss about how this unification helped us in understanding the true nature of time and another mind-blowing concept called time dilation.

Time as I described in my previous blog is very confusing, each and every person has their own measure of time which we don’t observe due to the speed with which we are moving is less. What is nature of time then, how can we describe past, present and future in space-time? is there any difference between these three or is it just a persistent illusion? let us find out answers for these questions.

Visualizing a 4-dimensional structure of space-time is very difficult, so most of the time to understand the space-time, it is converted to 2-dimensional structure. Before understanding the graph, knowing what an event is important. An event is something which happens at a particular place in space and at a particular time, one can specify it by using four numbers or coordinates.

Maxwell’s equation says that speed of the light should be constant irrespective of the source. Whenever a pulse of light is emitted from a point in space at a particular time, it is observed that as time goes on, the pulse becomes sphere of light spreading across the space. For ex: when ripples are formed when you throw a rock in the pond. If we take the snaps of this event at different time periods and kept above each other we would notice that it forms the shape of a cone. Tip of the cone would be the place at which pulse of light was emitted and then slowly spreading as sphere of light just as ripples of water.

The light which is spreading in the space forms a 3-dimensonal cone in the 4-dimensional space-time structure or graph. This cone is what we call future cone of the event, similarly we can also draw another cone called past cone below the future cone.

Now, we can divide the given event into three classes or three types. The events which can be reached from point P (P is the point where event takes place) by a particle or wave traveling at or below the speed of light is said to be in the future of P. whatever takes place at P has an effect on the future of P. similarly past of P can be defined as set of all events which leads us to reach the event P traveling at or below the speed of light. The below diagram shows the light cone in space-time graph

Some of the events neither lie in the future cone nor in the past cone, these events are said to be in the elsewhere section of P. whatever happens in this neither affects or gets affected by P. To understand this let’s take an example which happens daily. when the rays of sun start its journey at this very moment, it would not affect the things on earth at this moment, because it would be in the elsewhere event. We can only observe its affect after 8 minutes, as the light from the sun takes this much time to reach the earth. Only then we will be in the future light cone of the event that took place. In the same way the light which we see from the distant galaxies and stars are actually of past and our earth has now entered the future cone of the event. This tells us that what we are seeing is actually a past, a kind of time traveling.

Now, we saw the representation of past, present and future in the space-time but the real shocking revelation done by Einstein in his theory of relativity is that, there is no difference between past, present and future. All of this is just a persistent illusion which in turn says that time what we see is just an illusion. when I got to know about this, I was like Archimedes yelling in the streets “Eureka, Eureka”, but I was doing it inside my mind. Now, you might be thinking how’s it possible. Let me explain this in a simple way.

Consider all the things happening at right now moment, for ex: right now, I’m in front of my laptop writing my blog, my roommate is sleeping, flight is taking off from an airport, a star exploding somewhere in the universe. These are some of the events which are taking place at the very moment, in the common-sense point of view we all agree that these are happening right now. But when motion comes into play this common-sense view of time goes out of window. Imagine space-time as a loaf of bread. There are different ways to cut this loaf into slices, in the same way space-time can be cut into different ‘now’ slices. As motion affects the time and we all are moving with a particular speed, we cut the space-time loaf in a particular ‘now’ slice. But the person who is far away from us and has his own motion will have his own perception of ‘now’ slice. Which tells us that his ‘now’ is different and my ‘now’ is different. Let me give you an example to understand this confusing thing.

Imagine an alien sitting still some billion light years from earth. And here on earth I’m sitting on the bench reading a book. Since we both are still and our clocks are ticking at the same rate, we both share same ‘now’ time on slice.

Now, imagine alien sitting on bike and moving away from earth, this makes our clocks ticking at different rates and we no more share same ‘now’ slice. Alien’s ‘now’ slice will be cut into a different angle. Even if the angle is small, due to vast distance it creates such a large difference that Alien will be seeing 200 years past of earth. What’s even stranger is direction makes the difference too. Imagine alien moving towards the earth now, this makes alien’s ‘now’ slice cutting into the future. His ‘now’ would be seeing the future of earth. I would no longer be sitting on the bench there and the alien would be seeing my great, great, great grand daughter or son time traveling or teleporting.

This says that your ‘now’ can be my past, your ‘now’ can be my future and we both are at our own ‘now’ time, then the past is real and the future is also real. Which concludes that past, present and future all exist at the same time. there is no difference between these three and it’s just an illusion. everything that has ever happened or will happen all exists in this big loaf of space-time bread.

The universe in which we are living is lot stranger than what we thought, its beyond of our thoughts and imagination. As my favourite astrophysicist Neil deGrasse Tyson says “we are stardust brought to life, then empowered by the universe to figure itself out and we have only just begun”.

SPACE-TIME CONTINUUM

Space-time continuum: An introduction to the baffling concept of

Albert Einstein

  

On 25^th November 1915 a theory was released by a scientist which shook the whole world of classical mechanics, ‘The theory of relativity’ by Albert Einstein. Until this date we had heard of space and time as independent things but in this theory, Einstein unified the space and time as one i.e. space-time continuum.

Before moving towards the concept of space-time continuum, let us study space and time independently and a brief touch upon history of classical mechanics or as it is said Newtonian physics.

So, what is space?

When I say space most of us picture the outer space which is far away from earth, but space can be found everywhere. Atoms which are the basic ingredients of everything we see, actually contains 99.99% of space. So, the chair you are sitting on, the computer you are using is nothing but empty space. We understand what space is but we don’t know what exactly space is. Mathematically space is 3-dimensional with the co-ordinates x, y, z. Now, you must be thinking how can empty space be 3-dimensional. Empty space is not really empty it has lot going inside. In simple words we can say space is real i.e. it contains something which we can’t see. space can bend, it can twist and it can ripple. Space is still a mysterious book with lots of hidden stories which are yet to be told.

We know what space is now but the most confusing and unanswerable question is what is time?

We encounter time every day in our life, we can tell what time it is now but we can’t tell what time itself is. What if I say “we don’t have time we have time’s”, that’s a bit difficult sentence to grasp so let’s put it in simple words. Each individual or each one of us have different measures of time and it is affected by our motion i.e. how we move. but why don’t we see the difference? Why our clocks are ticking at the same rate?

Its because the speed with which we move is so tiny that we don’t see any difference.

 So, how was time born?

Time is said to be born at the very moment of big bang. There was no time before this, that’s the reason we can’t imagine what was before big bang. We still find it difficult to answer what exactly time is but all we can say is time is just an illusion.

So, now we have idea of what space and time are, but to understand space-time continuum we must know what was Newton’s view on space and time which we call as classical mechanics or Newtonian physics.

Aristotle and Newton both believed that time is absolute i.e. time would be same whoever measures it but the difference between both is Aristotle had a preferred state of rest or we can say absolute space, he thought earth is at rest but according to newton’s laws earth was rotating this, led to lack of absolute rest or space in his laws. Lack of absolute space means that one could not determine whether two events that took place at different times occurred at the same position in space. Newton refused to accept the lack of absolute space and continued his work. Time is separate form and is independent of space. it holds good for apples, planets which move slowly but we have to change our ideas on space and time when things are moving at or near the speed of light.

 The first attempt to tell that light had definite speed was done by Danish astronomer Christensen Roemer in 1676 but his answer was not accurate but it was near to it. later James clerk Maxwell gave us the exact speed of light which is 186,000 miles or 3*10^8 m/s. Newton had got ridden of the idea of lack of absolute space which was implied by his own laws to which he got lots of criticism. So, if light is moving with a definite speed then it must be moving with relative to something which is at rest. So, they came up with the idea that light moved relative to ‘ether’ which is present all over the space. When we measure the speed of light relative to ether it would be same but different observers moving relative to ether would measure different.

But in 1887 Michelson and Morley showed that speed of light measured along with the rotation of earth and right angle to the rotation of earth were same, which meant speed of light is exactly same whoever measures it, which questioned the newton’s and Maxwell’s work. This what we saw is a brief history of classical mechanics where Newton says time is absolute and there is no absolute space.

Now, we will see what is space-time continuum and how it destroyed the Newtonian physics.

In 1905, Albert Einstein said that time is not absolute, everyone has their own measure of time which is affected by the motion in space. For ex: imagine I’m moving at the speed of light and I have clock with me, you are standing with another clock in your hand observing me. When I move, you would see that my clock is ticking slower than yours and for me your clock would be ticking faster than mine. He also noticed that space would adjust itself according to the speed of the object. This made him realize that space and time are not independent, they are actually one and called it space-time continuum. 

Space-time continuum is like a fabric or rubber sheet which is spread all over the space. All the planets, stars are actually rotating on the space-time fabric creating a bend in the fabric. Einstein said that gravitational force is not produced by “two bodies having masses m1 and m2 separated by some distance r” [which was said by the newton in his law of gravitational force F=Gm1m2/r^2] but instead it is produced by the bend in the space-time which is made by heavier objects like planets and stars. To make you people understand this, I have an example. Imagine a stretched rubber sheet or fabric. when you put a heavy ball on it, it creates a bend on the fabric. Now, put a smaller and lighter ball inside that bend, what happens is the smaller ball rotates around the heavy ball with a constant velocity. It neither falls in the bend nor moves away from it, the ball just keeps rotating around the heavier ball in a certain position with constant velocity. This is exactly how planets rotate around the sun and moon’s around planets. The heavier the object is, larger the bend in the space-time fabric. Black holes are so heavy that they actually wrap the space-time around them. That’s why gravity is more and time stops around them. This discovery from Einstein destroyed the entire classical mechanics created by Newton. Yet today we still study the law of gravitational force created by Newton, it’s because we are comfortable with it and easy to understand and also it holds good in common sense point of view. Mathematically space-time is 4-dimensional with 3-dimensions of space and 1-dimension of time, therefore it is very difficult to imagine a 4-dimensional structure.

 After this there were many tests conducted to check whether Einstein’s theory was correct. One such test was conducted by NASA in 2004 which tested whether space-time fabric produced gravity. The mission was called gravity probe-B. NASA sent a satellite called gp-B which had 4 gyroscopes attached to it and gyroscopes were aligned in such a way that their tip pointed straight at the nearest star. If gravity is produced due to the bend in space-time fabric then due to it, gyroscopes would change the angle. And after continuously observing them they found out that the tip which was pointing straight at the nearest star was actually tilted at some angle. This proved that Einstein’s theory was right.

What we have studied until now is just an introduction to the space-time continuum of theory of relativity. In my next blog I will be telling how space-time continuum gave us the true nature of time, difference between past, present and future and time dilation. So, be ready for more mind boggling theories in my next blog.  

DARK MATTER AND DARK ENERGY

Dark matter and dark energy

The surroundings we see and the materials we use contains of matter. The matter as we know is something which occupies space and has some mass, these matters contains atoms and molecules. These atoms contain particles such as protons, electrons and neutrons. In other words, we can call this matter as baryonic matter. But the interesting and shocking fact is that the matter we see i.e. the visible universe, the sun, other stars and the galaxies which contains these baryonic matters comprises less than 5% of the entire mass of the universe. The question which arises here is, what is that thing which occupies 95% of the mass of the universe?

The answer for this question is, In the entire universe baryonic matter comprise 5% of mass and the rest of the universe contains mysterious and invisible substance called dark matter (25%) and a force which counteracts gravity called dark energy (75%). This is probably the most shocking discoveries of the 20^th century. 

Let us learn about this mysterious and invisible thing in the space which we call it as dark matter and dark energy.

Dark matter

Dark matter has no particular definition, we still don’t know exactly what dark matter is but our scientists are pretty sure that it does exist because we can see the effects of it on galaxies. Scientists are not able to directly detect the dark matter as it doesn’t interact with the light and is invisible. But after a lot of study scientists have few ideas what dark matter can be, dark matter contains exotic materials which doesn’t react with the normal matter and light but still exerts a gravitational pull. The question which haunts us the most is from where do this dark matter came from, according to Dr. Stephen hawking at the beginning of the big bang, universe is thought to have zero size but as it started expanding temperature of the matter or radiation decreased. One second after big bang temp would have fallen about thousand million degrees. At this time universe would have contained particles like photons, electrons, neutrinos and their antiparticles with few protons & neutrons.

As it continued to expand and temp dropped, the rate at which electrons and anti electrons produced fell and these both annihilated with each other to form more and more photons leaving behind only few electrons. The particles which remained after this are neutrinos/anti neutrinos, these cannot be annihilated with each other as they don’t interact among themselves and with others very weakly. So, they should be still around today and it is believed that they may be in the form dark matter. But is it true or false we don’t know yet.  Now, let me tell you the effect of dark matter on some of galaxies and its stars. According to standard physics stars near edges of the spinning galaxies should move much slower than the stars near the center of the galaxy but according to recent observations stars which are present near the edges have more or less equal speed as the stars near the center of the galaxy. 

This result shows that stars near the edges are getting affected by gravitational field by unknown mass i.e. dark matter. Now, let us move on to learn about dark energy.

Dark energy

Dark energy is even more strange and mysterious, as of dark matter even dark energy has no particular definition for itself. it cant be detected, it cant be measured and it cant be tasted but we can see its effects clearly. All we know is it’s a repulsive energy which counteracts gravitational force.

 In 1929 Edwin Hubble said that light emitted from distant galaxies shifted to the red end of electromagnetic spectrum, this shift is what we call as red shift. It usually occurs because universe is expanding and wavelength of the light goes on decreasing. According to recent studies it has been seen that universe is expanding at a faster rate than what scientists expected, which is really a shocking news for them, because earlier it was believed that pull of gravity would slow down the expansion or even retract at some point and collapse on itself. The increase in the speed of expansion is due to a repulsive force present in the empty space and the interesting fact about it is, it increases as the universe expands. this invisible force is governing the expansion of the universe and is called as dark energy. sounds bit scary, right? 

The idea of dark energy dates back to 1917 when Einstein gave a cosmological constant as a mathematical aid for his static universe theory after applying general theory of relativity to it. According to Albert Einstein universe is static i.e. its not expanding and has uniform distribution of matter across the universe and is spherical in shape, to support this he gave a equation called Einstein field equation which is λ = 1/R² = κρ/2  where k is called as cosmological constant. It is a force which counteracts gravitational force, which controls or stops the collapsing of universe on itself. But later he discarded it as experiments showed that universe is continuously expanding.

 It is very interesting how ‘cosmological constant’ was called one of the biggest blunders of Einstein is now called as dark energy. Dark energy is something which is mainly found in empty space and this energy is stronger than any energy in the world. Therefore, empty space is not really empty but contains more energy than everything else combined in the universe. Till today we are unable to know what exactly dark matter and dark energy are and what are its properties. I hope we discover about it sooner and solve the mystery of it.

We think that we know everything about this universe but we are still apes holding smartphones in the tiny island called as earth in the ocean of universe.