Why We Can Never Build The Time Machine

how to build a time machine impossible physics science

It has been a long, unfulfilled dream of humankind to obtain control over the passage of time. One cannot help but fantasize about bending time backwards, pause its eternal flow and dodge the inevitable death if technologically possible.

Clearly, time is a captivating phenomenon. That is why, a common theme in all science fiction is time travel. However, is building the time machine so trivial as depicted in the movies, like Back to the future? Is it theoretically as well as practically allowed?

What we gather about time travel from fiction is that it is either going back to a bygone era or jumping forward in the future. Time travel is a trip not in space which has three dimensions, but it is a journey in the fourth time dimension, the one we do not understand fully.

Theory of relativity


In non-relativistic physics, time was absolute, independent of the observer and same throughout the universe. This was proposed by English scientist Sir Isaac Newton when he thought that time progressed at consistent pace for everyone everywhere.

But in relativity, as theorized by German physicist Albert Einstein, time is no longer an absolute concept.

Firstly, time is treated like an alternate dimension to spatial dimensions of length, width and height. In other words, time is a new corridor to pass through.

Secondly, time is not the same for everyone everywhere as Newton had assumed. Time slows down as you travel faster, for example.

In fact, when subatomic particles are accelerated to nearly the speed of light, their lifetimes expand dramatically. They would usually decay faster, but when moving at relativistic speed inside the particle accelerator, they experience time more slowly (relative to other particles) and live longer.

Furthermore, from general theory of relativity, an upgraded version of special relativity, it is known that time passes more slowly for objects in strong gravitational fields, than for those objects which stay far from such fields.

As a result, if there were twin brothers and one of the twins orbited a black hole while the other around the earth, can you guess which of the twins would be older?

is time travel possible why time machine is impossible

Coming back to the question: Is time travel as shown in the movies like Looper or Back to the future practical? Many scientists agree that the idea of time travel at the push of a button is not possible as it would violate the law of causality.

The paradox


Time's flow is like a river as it speeds up, meanders and slows down. Time can also have whirlpools and fork into two or more rivers, says American physicist and futurist Michio Kaku.

As soon as the button of the time machine is pressed, it may be possible for one to go backwards in a parallel world. Therefore, deprived of the opportunity to change the turn of events in the reality one came from. A new reality would be built from scratch, avoiding the grandfather paradox.

This idea of time travel was proposed by British physicist David Deutsch who used the terminology of multiple universes to solve the widely debated grandfather paradox.

The paradox comes from the idea that if a person travels to a time before their grandfather had children, and kills him, it would make their own birth impossible.

Deutschian time travel solves the paradox only theoretically. The time traveler emerges in an alternate universe, but very similar to his own. Can such universes pop in and out of existence merely on the whim of the time traveler? The idea sounds good on paper but its practical possibility is highly doubtful.

What is possible


As per most scientists and engineers, time travel is impossible as you have seen in the movies. The late English astrophysicist Stephen Hawking once joked: "I have experimental evidence that time travel is not possible." Hawking hosted a party for time travelers in 2010, but no one came.

Yet, we have observed that time slows down and does not always run at the same pace everywhere, which can help to travel forward in time, at least, relative to another. As shown in the realistic movies like Interstellar (2014).

Also, when we observe the universe, we are looking back in time. Our own Sun’s light, for instance, takes about 8 minutes to reach on earth. We see the Sun the way it was 8 minutes ago; so if the Sun disappeared this instant, we wouldn't know.


You will be surprised to know that NASA's James Webb telescope can study light that was emitted by the most ancient galaxies 10 billion years ago. This means, we can peek at the birth of the universe, more or less, if we design an even larger, better telescope.

Summing up


Time travel at the push of a button is out of the question. To construct such a machine violates not only the laws of physics but also common sense. It is much like building a perpetual motion machine, a hypothetical machine that can do work infinitely without an external energy source.

Lastly, reiterating that time travel is far more impossible technically than it is theoretically. There may still be undiscovered physics that allows construction of a time machine. It might be possible but would involve vast amounts of energy and money.

10 Inspiring Quotes From Richard Feynman's Letters

quotes by richard feynman letters

Richard Feynman was a Nobel Prize winning American physicist whose letters have grabbed the attention of media far and wide. They included jokes, anecdotes, puzzles and news for his parents while he worked at institutions across America.

The following 10 quotes by Richard Feynman are extracted from the book titled, Don't you have time to think? edited by his daughter Michelle Feynman. The book, published in April 2005, is a unique collection of Feynman's letters.

1) Letter to mom Lucille Feynman, Oct 1939: Professor Wheeler was called away suddenly last night so I took over his course in mechanics for the day. I spent all last night preparing. It went very nicely and smoothly. It was a good experience - I guess someday I will do a lot of that.

Physicist John Wheeler was Feynman's doctoral advisor. This was probably Feynman's first lecture he gave in the absence of Prof Wheeler, as mentioned. He seemed to have enjoyed teaching and wanted to share that feeling with his mother.

2) Tell pop I have made out a time schedule so as to efficiently distribute my time and will follow it quite closely. There are many hours when I haven't marked down just what to do but I do what I feel is most necessary then or what I am most interested in.

quotes by richard feynman letters

Like most students Feynman also struggled to manage time. At the time this was written Feynman was quite early in his twenties. As suggested by his father, Feynman made a time table to achieve maximum level of productivity in a day.

3) 1940: I am listening to a course in physiology, study of life processes, in the biology dept. It is a graduate course. I don't know at all as much as the 3 other fellows in the class but I can understand and follow everything easily.

Just like this, Feynman was led to new adventures in life by his curiosity. In a 1979 interview given to Omni magazine Feynman said: I don't know anything, but I do know that everything is interesting if you go into it deeply enough.

4) Letter to Arline, the love of his life, year 1945: I feel I am a reservoir for your strength. Without you, I would be empty and weak, like I was before I knew you... but your moments of strength make me strong and thus I am able to comfort you with your own strength when you are down.

5) Study hard what interests you the most in the most undisciplined, irreverent and original manner possible. Letter to J. M. Szabados (November 1965)

6) Letter to Koichi Mano, February 1966: You say you are a nameless man. You are not to your wife and to your child. You will not long remain so to your immediate colleagues if you can answer their simple questions when they come into your office.

You are not nameless to me. Do not remain nameless to yourself — it is too sad a way to be. Know your place in the world and evaluate yourself fairly, not in terms of the na├»ve ideals of your own youth, nor in terms of what you erroneously imagine your teacher's ideals are.

7) Do not read so much, look about you and think of what you see there. Letter to Ashok Arora, January 1967.

8) The real question of government versus private enterprise is argued on too philosophical and abstract a basis. Theoretically, planning may be good. But nobody has ever figured out the cause of government stupidity — and until they do (and find the cure), all ideal plans will fall into quicksand. 1963 letter to his wife, Gweneth.

9) Tell your son to stop trying to fill your head with science — for to fill your heart with love is enough! Note to the mother of Marcus Chown.

10) Last letter to Arline, written in 1946, after her untimely death due to prolonged tuberculosis: I adore you sweetheart. I find it hard to understand in my mind what it means to love you after you are dead. But I still want to comfort and take care of you — and I want you to love me and care for me.

I want to have problems to discuss with you — I want to do little projects with you. My darling wife, I do adore you. You, dead, are so much better than anyone else alive. I love my wife. My wife is dead. PS: Please excuse my not mailing this but I don't know your new address.

5 Women Who Deserved To Win Nobel Prize In Physics

women who deserved to win nobel prize in physics

The Nobel Prize can be as controversial as it is prestigious. There is a long history of women going unrecognized, especially in the field of physics. Many female scientists have made ground-breaking contributions that should have won them a Nobel Prize, but they never became laureates.

Since 1901, of the 219 Nobel Prize winners in physics, only 4 were women. The following is a list of at least five more women who deserved to win the Nobel Prize but did not receive the top honor. Instead, the prize was either awarded to their male colleagues, advisor or not considered at all.

Chien-Shiung Wu


Chinese-American experimental physicist is best known for conducting what is called the Wu experiment. She showed that parity, which is conserved for electromagnetic and strong forces, is not conserved for weak force.

The violation of parity meant that if there was a mirror version of the real world then it would be possible to distinguish between the two. Before the Wu experiment, it was assumed by physicists that parity was always conserved.

Her male colleagues Tsung-Dao Lee and Chen-Ning Yang received the 1957 Nobel Prize in physics for the idea, whereas Wu's contribution in the discovery only got a mention in the Nobel Prize acceptance speech.

Jocelyn Bell Burnell


Astrophysicist from Northern Ireland picked up an interesting signal as a research student that turned out to be the first rotating neutron star, Pulsar, ever known. The discovery was recognized by the award of 1974 Nobel Prize in physics. However, Bell was excluded from the recipients.

Astronomers Martin Ryle and Anthony Hewish (doctoral advisor of Bell) won the Nobel Prize which was the first physics award given in recognition of astronomical research. Fellow astronomer Fred Hoyle strongly objected to Bell's omission, but to no avail.

Emmy Noether


German mathematician Amalie Emmy Noether made extraordinary contributions to both physics and mathematics. In physics, among many discoveries, Noether's theorem is the most famous that explains the relation between conservation laws and symmetry.

women who deserved nobel prize in physics

Her expertise in mathematics was sought after by famous mathematicians such as David Hilbert to understand the theory of general relativity. Albert Einstein described Noether as the most important woman in the history of mathematics.

Unfortunately, the scope of Noether's exceptional work in physics was not recognized during her lifetime. She died in 1935 at the relatively young age of 53 which is probably one of the reasons why she never won a Nobel Prize.

Lise Meitner


Austrian-Swedish physicist Lise Meitner was among the first to discover nuclear fission. In nuclear fission, atoms are split apart, which releases zero-emission clean energy, as the total mass of the resultant particles is less than that of the initial reactants.

Nobel committee for chemistry decided that German chemist Otto Hahn should be the sole winner of the Nobel Prize in chemistry for his role in understanding fission. The committee members failed to understand why the physics community regarded Meitner's work as seminal.

Lise Meitner spent most of her scientific career in Germany. She was the first woman to become a full professor of physics in Germany. Albert Einstein nicknamed her as the German Marie Curie when she discovered the radioactive element Protactinium.

Vera Rubin


American astronomer discovered a discrepancy in the predicted and observed angular momentum of galaxies which was the first evidence for the existence of dark matter, which makes 27% of the universe. In fact, the matter we know of makes only 5% of the universe.

In 1970s, with her long time collaborator Kent Ford, Vera Rubin found that there was more gravitation in individual galaxies than normal matter could account for. They showed that there must be at least six times more dark matter than visible mass, which is an accepted fact today.

Dark matter research gained momentum after their discovery but neither Ford nor Rubin won the Nobel Prize. Rubin fought hard to gain credibility in a traditionally male-dominated field of astronomy. Rubin died in 2016 after waiting over 40 years for a Nobel Prize recognition.

First Images From NASA's Webb Telescope Revealed

first image nasa james webb telescope hubble deep field image

First image (credit: NASA, ESA, CSA) by the Webb Telescope is of galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago, the time when our planet Earth just began to form. Surrounding the cluster are tiny unseen objects of the universe as they were 13 billion years ago, shortly after the Big bang.

SMACS 0723, a massive object, is bending the light rays coming from the distant galaxies behind it. The Webb telescope has brought those galaxies into sharp focus. This phenomenon is called gravitational lensing and is based on Einstein's theory of relativity.

The image was taken by Webb's near-infrared camera and took about 12.5 hours to be assembled from a collection of images taken at various wavelengths. When the Hubble Space Telescope took a similar deep field image it took several weeks!

The first deep field was unveiled by the president of the United States Joe Biden during a White House event. “It’s hard to even fathom,” he commented.. “It’s astounding. It’s an historic moment for science and technology, for America and all of humanity.”

Thousands of galaxies that have come into Webb's infrared view for the first time would fit in a single grain of sand held at arm's length by someone on the ground. These images will help astronomers to calculate the compositions of the earliest galaxies.

The telescope, named after the longest serving NASA administrator, took over 30 years for completion and could revolutionize our understanding of the universe. Its infrared capabilities will allow humans to see back in time to the first galaxies and study their evolution.

hubble vs webb telescope first image deep field nasa

Webb is the official successor of the Hubble space telescope. Its operations are led by NASA with its partners: ESA (European Space Agency) and CSA (Canadian Space Agency). The camera that took this image was built by the University of Arizona and Lockheed Martin’s Advanced Technology Center.

5 Nikola Tesla Quotes For Making A Better World

nikola tesla engineer physics quotes by tesla

Nikola Tesla was a Serbian inventor and engineer who is best known for his contribution to the development of alternating current system and his feud with American inventor Thomas Edison over whose electricity supply method would power the world.

Tesla was also a deeply spiritual and a forward thinking man of culture. He consumed Mark Twain's works early on in life and was highly influenced by eastern philosophies in the latter part of his life. In this post, let us take a look at 5 of Tesla's famous ideas that may change the world.

Enjoy solitude

For much of his life, Nikola Tesla was lonely and he was never married. Some of Tesla's best work came out of solitude and he acknowledged this, saying: The mind is sharper and keener in seclusion. No big laboratory is needed in which to think. Originality thrives in solitude free of outside influences beating upon us to cripple the creative mind. Be alone, that is the secret of invention; be alone, that is when ideas are born.

Think reasonably

Nikola Tesla was born and raised in an orthodox Christian family. Later in life he did not consider himself to be a believer in the orthodox sense. Tesla said: To me, the universe is simply a great machine which never came into being and never will end. The human being is no exception to the natural order. Man, like the universe, is a machine.

Tesla favored rationality and always opposed religious fanatism. He believed: Nothing enters our minds or determines our actions, and what we call soul or spirit, is nothing more than the sum of the functionings of the body. When this functioning ceases, the soul or the spirit also ceases.

Preach equality

Nikola Tesla advocated strongly for women to pursue scientific endeavors. Women will startle civilization with their progress, Tesla predicted. He said in an interview: The female mind has demonstrated a capacity for all the mental acquirements and achievements of men, and as generations ensue that capacity will be expanded. The average woman will be as well educated as the average man, and then better educated, for the dormant faculties of her brain will be stimulated to an activity that will be all the more intense and powerful because of centuries of repose.

Future of energy

Nikola Tesla was a visionary who endorsed renewable energy sources like solar, wind and water. Of the three, Tesla was most in favor of sun's practically infinite untapped energy. He said: The sun's rays beat the earth incessantly and supply energy at a maximum rate of over four million horsepower per square mile. The average energy received per square mile in any locality during the year is only a small fraction of that amount, yet an inexhaustible source of power would be opened up by the discovery of some efficient method of utilizing the energy of the rays.

To achieve peace

Nikola Tesla realized much later in his life that the fights between individuals, or even among governments and nations, result from misunderstandings, that are always caused by the inability of appreciating one another's point of view.

Tesla's way of accomplishing peace is simply, understanding and acknowledging the differences. To resist our inherent fighting tendency, the best way is to dispel ignorance of the doings of others. The most important step is to aid exchange of thought and ideas.

4 Unsolved Mysteries About The Higgs Boson

higgs boson god particle 10 years higgs LHC cern

On July 4, 2012 the Higgs Boson particle was discovered at the Large Hadron Collider that is operated by CERN, the European organization for nuclear research. It took 60 years to first detect the elusive particle and there is still a lot to learn about it, scientists say.

CERN closed the largest particle accelerator for maintenance work that was extended due to delays caused by the pandemic. In 2022, scientists celebrated the 10th anniversary of Higgs Boson discovery. They now hope to uncover more as LHC has gotten back in action after 3-year hiatus.

1. Is the Higgs connected to dark matter?


Since dark matter makes up about 30% of the universe's mass and considering Higgs boson's relation to mass, scientists want to find if the two are connected somehow. They may explore, for example, whether or not the Higgs boson particle decays into a dark matter particle.

As of current understanding, scientists know that the Higgs boson particle can decay into boson, fermion and muon. The goal is to see which other kind of mysterious particle the Higgs boson particle can decay into. So far no unusual particles have been detected in collider experiments.


2. Does the Higgs boson interact with itself?


Matter particles (such as electron) move through the Higgs field and acquire their characteristic mass. More interaction means more the mass attained by the particle. Scientists hope to run experiments to find if the Higgs boson particle interacts with itself as predicted by the standard model.

This is the main question about the Higgs particle right now, say scientists working at the council for nuclear research. According to the standard model, when the Higgs particle self-interacts, it would create pairs or triplets of Higgs bosons, that are yet to be detected in the experiments.

3. Are there other Higgs particles?


The Higgs boson is an excitation of the all-pervading Higgs field that helps other particles pass through it and acquire mass. For this reason, it was nicknamed the God particle by the media, although some scientists refer to it as the Goddamn particle as it took so long and multi-billion dollars to find it.

The particle which was found in 2012 has zero spin and no electric charge. Theories alternate to the standard model predict the presence of more than one kind of God particle. Detection of additional Higgs particles in the collider experiments would mean that there must be new physics out there.

4. How does the Higgs interact with matter?


One thing scientists know for sure is that the more massive a given particle, the greater its interaction with the Higgs field must be. The nuances of this are yet to be understood even though the measurements thus far match the predictions of the standard model, the precision of these measurements isn’t great enough.

Models other than the standard model propose the existence of one kind of Higgs particle that interacts only with heavy particles and another that interacts with only lighter particles. Similar exciting challenges in particle physics await scientists working at the large hadron collider.
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