Category Archives: Quantum Physics

Sunil Roys collection of poems titled Sisyphus on the SeeSaw is inspired by everything from psychology to quantum physics to art and philosophy

As an adventure consultant, Sunil Roy, a resident of Hennur, would work in the midst of nature for most of his time. Travelling to very remote locations, surrounded by nothing but trees, water, sands, forests meant that he got a lot of time to muse and contemplate over the mysteries of life.

And so, for the past few years, Roy would jot down his thoughts in the form of poems. Inspired and based on psychology, philosophy, art, quantum physics all of Roys favourite reading topics the poems, titled Sisyphus on the SeeSaw, often resemble Rorschach inkblots to readers: subject to interpretation.

Going to all these remote locations meant that he got a lot of time to reflect. For the last 15 17 years, I have been travelling, he says.

At first glance, the poems seem extremely obscure. But on closer scrutiny, they have nuggets of truth hidden. Even Roys name (Nil Ryo) is a clever pseudonym of his initials.

But writing poems, especially when they deal with heavy topics like quantum particles and psychology, is not an easy feat. Roy says that he had to consciously dumb down the concept to make it decipherable to everyone. If one is looking for some literary value in these poems, he/ she may not find it. But if you want some anomalies and conundrums, and a bit of psychology hidden, this book may fascinate you, he explains.

Drawing hands by Escher is an apt paradox of what his book is about

Excerpts...

The Naxal A circle is formed by points if a single point starts to push or pull then soon all the points will roll on to each other and end up in a pile or fall flat as a line or even, perhaps, set the circle in a revolution.

Are you an East Bengaluru resident? Wed like to hear from you. email: seena.menon@timesgroup.com

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The Towns Mirror Special: Delving into the sleight of mind - Bangalore Mirror

Hear ye, hear ye! The gravity of the matter discussed in this article will be unprecedented! The mass of the topic - insurmountable! The velocity of thoughts spinning in your heart after reading - that of light! The shocking, awe-inspiring, and unbelievable topic is *drum roll* - physics jokes! And here you thought that we were going to be discussing how cute cats are That, of course, is also a case of great mass, but let's leave it for some other time.

So, physics jokes are probably the science jokes that test your smarts the most. To truly understand them, you have to at least know the basic functionalities of our world. For instance, the fact that apples fall down from a tree instead of floating right into the cosmos. Also, it would be good to understand the basic principles of mass, velocity, electromagnetism, thermodynamics, and quantum mechanics, of course. However, even if you're just a physics newbie, we are itching to show you these scientific jokes - we are so sure that you will find them to be a real riot!

Okay, so now it is time for you to gravitate towards the clever jokes we've prepared for you. They are, as per usual, just an atom down below. Once you're there and have checked out the funny jokes, vote for the ones that gave you a massive case of laughs. After all that is done - be sure to share these cool jokes with anyone who will understand their true gravity!

Whats the most terrifying word in nuclear physics?

Oops.

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Why is it best to teach physics on the edge of a cliff?

Because thats where students have the most potential.

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Why was Heisenbergs wife unhappy?

Because whenever he had the energy, he didnt have the time.

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Have you heard of the physicist who got chilled to absolute zero.

Hes 0K now.

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What a physicist hears when he watches Star Wars:

"May the mass times acceleration be with you!"

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Einstein developed a theory about space.

And it was about time too.

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"I was studying frequency in my physics class. Now my brain Hertz."

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Did you hear about the physicist who was reading a great book on anti-gravity?He couldn't put it down.

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A helium atom walks into a bar.

The barman says: "Sorry, we don't serve noble gas."

The helium atom doesn't react.

Trozuns Report

Do you know why physicists are bad at sex?

Because they cant find the position when they have momentum and when they find a position, they lose the momentum.

justforfunreddit Report

How many general-relativity theoretists does it take to change a light bulb?

Two. One to hold the bulb and one to rotate space.

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What did the Nuclear Physicist have for lunch?

Fission Chips.

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What did one electron say to the other electron?

Dont get excited. Youll only get into a state!

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Why is quantum mechanics the original "original hipster"?

It described the universe before it was cool.

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Why is electricity an ideal citizen?

Because it conducts itself so well.

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A man at a bar tells the bartender, "I'll have some H2O"

The man next to him says, "I'll have some H2O too"

He dies.

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Why does a burger have less energy than a steak?

Because its in its ground state.

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"I have a new theory on inertia, but it doesnt seem to be gaining momentum."

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Where does bad light end up?

In prism.

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A string theorist gets caught cheating on his wife and says, "Wait, I can explain everything."

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Why cant you trust an atom?

They make up everything.

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A neutron walks into a bar and asks, How much for a whiskey? The bartender smiles and says, For you, no charge.

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Physics is the science where it takes long, complicated equations to explain why round balls roll.

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Schrodinger and Heisenberg were out driving together when they were pulled over by a policeman.The cop walks up to the window and asks, Sir, do you know how fast you were going?Heisenberg replies, No, but I know exactly where I was.The cop is unamused and orders the physicists to open their trunk. He looks in and sees a dead cat.Do you know there is a dead cat in your trunk?Schrodinger replies, Well, I do now!

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Two atoms were walking down the street. One turns to the other and says,Oh, no! I think I lost an electron!

The other responds, Are you sure?!?

Yes, Im positive!

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What do you call 1 kilogram of falling figs?1 Fig Newton.

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How many physicists does it take to change a light bulb?

Eleven. One to do it and ten to co-author the paper.

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Old physicists dont die; their wavefunctions go to zero as time goes to infinity.

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What does E = mc2 mean?

Energy = milk chocolate squared.

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Definition of a tachyon: A gluon that hasnt dried completely.

Alternate definition: A subatomic particle devoid of taste.

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What did the male magnet say to the female magnet?

"From your backside, I thought you were repulsive. However, after seeing you from the front, I find you rather attractive."

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What is an astronomical unit?

One hell of a big apartment.

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How many astronomers does it take to change a light bulb?

None, astronomers prefer the dark.

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The facts about electricity might shock you.

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All the physicists meet up in heaven and decide to play a game of hide and seek. They decide that Fermi will be the seeker, so he closes his eyes and begins counting to 100.

All the physicists scatter, except for Newton, who calmly reaches into his pocket, takes out some chalk, and draws a square one metre on a side.

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96 Physics Jokes That Might Give You A Massive Case Of Laughs - Bored Panda

Credit: Pixabay.

Einsteins theory of general relativity was revolutionary on many levels. One of its many groundbreaking consequences is that mass and energy are basically interchangeable at rest. The immediate implication is that you can make mass tangible matter out of energy, thereby explaining how the universe as we know it came to be during the Big Bang when a heck lot of energy turned into the first particles. But there may be much more to it.

In 2019, physicist Melvin Vopson of the University of Portsmouth proposed that information is equivalent to mass and energy, existing as a separate state of matter, a conjecture known as the mass-energy-information equivalence principle. This would mean that every bit of information has a finite and quantifiable mass. For instance, a hard drive full of information is heavier than the same drive empty.

Thats a bold claim, to say the least. Now, in a new study, Vopson is ready to put his money where his mouth is, proposing an experiment that can verify this conjecture.

The main idea of the study is that information erasure can be achieved when matter particles annihilate their corresponding antimatter particles. This process essentially erases a matter particle from existence. The annihilation process converts all the [remaining] mass of the annihilating particles into energy, typically gamma photons. However, if the particles do contain information, then this also needs to be conserved upon annihilation, producing some lower-energy photons. In the present study, I predicted the exact energy of the infrared red photons resulting from this information erasure, and I gave a detailed protocol for the experimental testing involving the electron-positron annihilation process, Vopson told ZME Science.

The mass-energy-information equivalence (M/E/I) principle combines Rolf Launders application of the laws of thermodynamics with information theory which says information is another form of energy and Claude Shannons information theory that led to the invention of the first digital bit. This M/E/I principle, along with its main prediction that information has mass, is what Vopson calls the 1st information conjecture.

The 2nd conjecture is that all elementary particles store information content about themselves, similarly to how living things are encoded by DNA. In another recent study, Vopson used this 2nd conjecture to calculate the information storage capacity of all visible matter in the Universe. The physicist also calculated that at a current 50% annual growth rate in the number of digital bits humans are producing half of Earths mass would be converted to digital information mass within 150 years.

However, testing these conjectures is not trivial. For instance, a 1 terabyte hard drive filled with digital information would gain a mass of only 2.5 10-25Kg compared to the same erased drive. Measuring such a tiny change in mass is impossible even with the most sensitive scale in the world.

Instead, Vopson has proposed an experiment that tests both conjectures using a particle-antiparticle collision. Since every particle is supposed to contain information, which supposedly has its own mass, then that information has to go somewhere when the particle is annihilated. In this case, the information should be converted into low-energy infrared photons.

According to Vopsons predictions, an electron-positron collision should produce two high-energy gamma rays, as well as two infrared photons with wavelengths around 50 micrometers. The physicist adds that altering the samples temperature wouldnt influence the energy of the gamma rays, but would shift the wavelength of the infrared photons. This is important because it provides a control mechanism for the experiment that can rule out other physical processes.

Validating the mass-energy-information equivalence principle could have far-reaching implications for physics as we know it. In a previous interview with ZME Science, Vopson said that if his conjectures are correct, the universe would contain a stupendous amount of digital information. He speculated that considering all these things the elusive dark matter could be just information. Only 5% of the universe is made of baryonic matter (i.e. things we can see or measure), while the rest of the 95% mass-energy content is made of dark matter and dark energy fancy terms physicists use to describe things that they have no idea what they look like.

Then theres the black hole information loss paradox. According to Einsteins general theory of relativity, the gravity of a black hole is so overwhelming, that nothing can escape its clutches within its event horizon not even light. But in the 1970s, Stephen Hawking and collaborators sought to finesse our understanding of black holes by using quantum theory; and one of the central tenets of quantum mechanics is that information can never be lost. One of Hawkings major predictions is that black holes emit radiation, now called Hawking radiation. But with this prediction, the late British physicist had pitted the ultimate laws of physics general relativity and quantum mechanics against one another, hence the information loss paradox. The mass-energy-information equivalence principle may lend a helping hand in reconciling this paradox.

It appears to be exactly the same thing that I am proposing in this latest article, but at very different scales. Looking closely into this problem will be the scope of a different study and for now, it is just an interesting idea that must be followed, Vopson tells me.

Finally, the mass-energy-information equivalence could help settle a whimsical debate that has been gaining steam lately: the notion that we may all be living inside a computer simulation. The debate can be traced to a seminal paper published in 2003 by Nick Bostrom of the University of Oxford, which argued that a technologically adept civilization with immense computing power could simulate new realities with conscious beings in them. Bostrom argued that the probability that we are living in a simulation is close to one.

While its easy to dismiss the computer simulation theory, once you think about it, you cant disprove it either. But Vopson thinks the two conjectures could offer a way out of this dilemma.

It is like saying, how a character in the most advanced computer game ever created, becoming self-aware, could prove that it is inside a computer game? What experiments could this entity design from within the game to prove its reality is indeed computational? Similarly, if our world is indeed computational / simulation, then how could someone prove this? What experiments should one perform to demonstrate this?

From the information storage angle a simulation requires information to run: the code itself, all the variables, etc are bits of information stored somewhere.

My latest article offers a way of testing our reality from within the simulation, so a positive result would strongly suggest that the simulation hypothesis is probably real, the physicist said.

Read more here:

Is information the fifth state of matter? Physicist says theres one way to find out - ZME Science

Mar 11, 2022(Nanowerk News) The worlds smallest car race will return to Toulouse (southwestern France) on 24-25 March. Eight international teams will be at the starting line for the competition. Christian Joachim, a CNRS research professor and the event organiser, provides details regarding the issues involved.Event: NanoCar Race II, March 24-25, 2022 at CEMES (La Boule), in Toulouse. The race will be broadcast on the events The nanocars of the eight teams selected for the second edition of the NanoCar Race. (Image: IC/IPMC CNRS Strasbourg ; IMDEA Madrid/Univ. Linkping ; Technical Inst./CFAED Univ. Dresde ; NIMS Tsukuba ; Univ.Paul-Sabatier/CEMES CNRS Toulouse/NAIST Nara ; Ohio Univ. ; Rice Univ./Graz Univ. ; CFM DIPC CSIS San Sebastian/CIQUS Univ. Santiago de Comp.)Five years after the first NanoCar Race, this new and to say the least unique race is finally returning to the CEMES. Why such a long wait?Christian Joachim: The very first molecule-car race in April 2017 required four years of preparation. For this second edition, the call for applications was made in March 2018, with a view to holding the competition in Toulouse in 2020. In late 2019, the international organising committee selected 11 teams from the 23 statements of intent submitted from all continents. Everything was in place for the race to be held in the spring of 2020. Unfortunately the Covid-19 epidemic broke out, forcing us to put the event on standby until July 2021. After this long break, only eight teams remained. We interviewed them by videoconference in September 2021, with support from the French embassies in their respective countries as well as the CNRS offices abroad, in order to confirm their level of commitment. The eight teams then travelled to Toulouse on 23 November, 2021 to officially present their molecule-car during CNANO 2021. Together we set a date for the race.What is the MEechanics with MOlecule(s) (MEMO) project, which this new edition of the NanoCar Race is part of?C. J.: To secure funding for this event, we decided to make it one of the deliverables for the MEMO H2020 project that began in October 2017. This European scheme included six academic partners. Its objective was to understand the mechanical rotational motion of a single molecule-machine on a supporting surface, for instance by constructing gears with a diameter of one nanometre and a rotation axis consisting of a single atom. Developing molecule-motors is another one of the MEMO projects objectives. Among other things, this second component involves measuring the motive force of a single molecule-motor. Connecting the second edition of the NanoCar Race to this project will enable us to more widely disseminate the scientific knowledge gained by controlling a single mechanical molecule, and be more specific than solution-based experiments.How does the scanning tunneling microscope that will capture the images of the race and fuel the molecule-cars operate? C. J.: We are mostly using the imaging function of the scanning tunneling microscope (STM). With a single atom at its tip, this high-precision instrument can scan a materials surface, while keeping that surface less than a nanometre away from the particle. At that distance, a tunneling current is established, on the order of 1 nanoampere for 1 volt of applied voltage. This weak current converted into an amplified voltage can stabilise the distance between the tip and the surface without them touching. This enables us to produce, line by line, an image of the observed material.The Swiss nanodragster from the first race was propelled by electric pulses from the STM microscope applied to a motor located near the back of the molecule (in blue). The dragster moves in different directions depending on the zone that is activated. (Image: Dr. Remy Pawlak and Pr. Ernst Meyer, University of Basel)For greater precision, the scanning should be performed at a temperature near absolute zero, around -270 C. This prevents the atoms that make up the tracks surface from being tossed about by thermal agitation. Once the molecule-car is on the racetrack, the driver uses the tip of the STM to supply energy and move the vehicle forward.To do this, the pilot can increase the voltage between the tip and the surface, or can leave the former at the same place on the molecule-car for a certain amount of time, between 100 milliseconds and a few seconds. In this latter scenario, the tunnel currents small inelastic effect through the molecule-car increases the vibrational energy of some of its mechanical degrees of freedom, which moves the car forward step by step, generally a few hundred picometres at a time (1 pm=10-12 m).Can you describe the structure of the track on which the nanocars will race?C. J.: The track was created on the surface of a pure gold crystal in this case a pastille 8 mm in diameter naturally featuring small grooves. These folds, which minimise the gold crystals surface energy, are arranged in straight lines of 100 to 200 nm, forming lanes for the molecule-cars. Track length differs from one gold pastille to another, as does the arrangement of narrow and wide grooves, which generally vary between 4-10 nm.Gold racetrack on which the molecule-cars move, inside a scanning tunneling microscope. (Image: Hubert Raguet / CEMES / CNRS Photothque)This layout depends on the preparation methods used by each competitor. At the end of each straight line in a given track, groups of atoms on the surface shift slightly, thereby creating a small bend measuring between 4-5 nm with a curve of 20-30 that connects it with the next straight line. This is the chief difficulty of the race, as a molecule-car can easily end up stuck on a bend. During the first NanoCar Race, drivers noticed that the most effective way to negotiate a turn was to bypass it on the right or left by following the next track.Below, experimental image (35 x 50 nm) obtained via scanning tunneling microscopy of the gold surface with 4 complete parallel tracks, recorded on the LT-STM microscope at the CEMES, in Toulouse. Track width varies between 4 and 6 nm. Top, scanning tunnelling microscopy image (2 x 5 nm) of the gold atoms on the edge of track 2. (Image: CEMES / CNRs)This year eight teams will compete. What do their nanocars look like?C. J.: Some molecule-cars, like the one from the Strasbourg Institute of Chemistry, have two wheels and a central chassis. Others, including that developed by the Spanish team from the Nanoscience IMDEA, have four wheels attached to a chassis. Those of the Japanese and French-Japanese teams have two wheels with paddles, and a foot at the back to protect the chassis from being crushed against the tracks surface. A dipole moment can be included in the frame via a small chemical grouping located at the front of the molecule. The prototype from Ohio University has two enormous wheels attached to a narrow chassis. The latter remains an essential feature regardless of the vehicles chemical structure. By raising the molecular structure to which the wheels or paddles are attached, the chassis reduces the molecule-cars interactions with the tracks surface.The chassis raises the molecular structure, in this case that of the French-Japanese team Toulouse-Nara, thereby reducing interactions with the tracks surface. (Image: Universit Paul-Sabatier / CEMES CNRS / NAIST)While most nanocars now rely on the dipole moment to move, some are still relying on the inelastic tunneling effect. What sets these two solutions apart?C. J.: By equipping their nanocar with a dipole moment, most teams will try to precisely steer it by using the electric field between the tip of the microscope and the surface of the track. The dipole moment also makes it possible for the STMs tip to attract the car when it is placed at the right distance. The objective is to cover the longest stretch for each pulse of voltage. The inelastic effect is a more challenging phenomenon to manage. It involves aiming the microscopes tip at a particular zone of the molecule, with a precision of a few dozen picometres. This strategy provides much better control over the path of the car.This years race has a mandatory slalom, which is meant to show the high manoeuvrability achieved by new generations of molecule-cars. While this obligation has been the subject of intense scientific debate among the competitors, it has mostly helped improve molecular designs. We are looking forward to determining whether the dipole moment or the inelastic effect is more competitive in this slalom trial.What changes have the races organisers made? C. J.: The rules for this new edition have firstly banned moving the car by mechanically pushing it directly with the microscopes tip. Unlike the first edition, where four of the six teams used the CEMES 4-tip STM microscope, this time each competitor will use their own STM microscope, which they will remotely control from Toulouse via the Internet. The teams also have to provide a high-definition image of their nanocar, with the help of the microscope, approximately every eight minutes. This new rule, called image by image by the international organising committee, should help the participants better negotiate the turns within a particular track.The drivers control the nanocars and their movement on the track via control screens. (Image: Hubert Raguet / CEMES / CNRS Photothque)As in 2017, the competition will be broadcast live on the Internet. Is there anything new in store in this regard?C. J.: The experimental images generated by the image by image rule will allow each team to produce a short animation film retracing the path of the molecule-car every hour, with a precision of a few picometres. These video sequences will be broadcast on the NanoCar Race YouTube channel, where the public can follow each cars trajectory. At the end of the event, which is planned to last 24 hours, the winner will be named i.e. the team that covered the longest distance in a track and its turns using the same molecule-car. As the features and shape of the gold track vary substantially from one competitor to another, a bonus will be given to teams whose route includes the most turns.Beyond the competition, the NanoCar Race provides an opportunity to advance research on molecular machines. C. J.:This race indeed seeks to elucidate the physical and chemical phenomena that make a molecule-car move in a controlled manner over a surface. In 2017, during training sessions for the first NanoCar Race, the Japanese and German teams were able to move their car without difficulty using an inelastic tunneling effect. But on the day of the race, their vehicle got stuck, for no known reason so far.What exactly are the scientific objectives of this new edition?C. J.: It could shed new light on the Maxwells demon thought experiment. According to this hypothesis, which was posited in 1870 by the Scottish physicist James Clerk Maxwell, it is possible to violate the second law of thermodynamics. To achieve this feat, Maxwell brought into play a small imaginary being smaller than the spatial extension of the thermal fluctuations of the surface meant to support it. Today, this miniscule being could have the chemical structure of a molecule-motor that would work by exclusively capturing energy from its supporting surface.With regard to translational motion, it would rather involve a molecule-car exclusively borrowing energy from the surface, in order to always move in the same direction. In any event, this new NanoCar Race could help us move from the demon hypothesis to an actual experiment, paving the way for developing future molecule machines. The race will see two types of molecule machines competing for the very first time: those equipped with a dipole moment based on a traditional propulsion method, and others with inelastic tunneling effect motors from quantum physics. Detailed analysis of how these two categories of nanocar perform should allow us to confirm whether an intrinsic quantum effect, such as the inelastic tunneling effect, provides greater manoeuvrability without consuming too much energy.

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The second NanoCar Race is off to a good start - Nanowerk

A team of scientists recently published a paper indicating that life on Earth is the result of what can only accurately be described as cosmic teleportation.

Humankind has long sought to penetrate the mystery of how life came to exist on our planet. But what if the only reason were here right now is because the universe cheats?

If we trace the origin of life back to the dawn of biology on Earth, we find ourselves rewinding tothe primordial soup from which our first ancestors rose.

However, the basic building blocks of life had to be present before anything could ooze its way out of the soup and into the future. So the question is: how did amino acids end up on Earth?

According to the research team, which included scientists from the Max Planck Institute and Friedrich Schiller University Jena, our origin story actually began in space.

Per the teams research paper:

Here we prove experimentally that the condensation of carbon atoms on the surface of cold solid particles (cosmic dust) leads to the formation of isomeric polyglycine monomers (aminoketene molecules).

In other words: the researchers experimentally formed complex amino acids in a space-like environment. This is significant because its long been believed that life was only able to form on the Earth because of its proximity to the sun.

This new research doesnt necessarily change that. Its clear life thrives on our planet due to its unique amenities. But if the basic building blocks of life, amino acids, can form into complex chains in the void of space, its possible the universe is practically teeming with the potential for life.

However, getting those building blocks to form in cold temperatures is no easy feat. First, you have to push the boundaries of chemistry by designing amino acids that can form in a waterless paradigm. Then you have to leave the laws of physics behind to overcome whats essentially an insurmountable barrier.

The gist of the problem is that molecules have greater thermal energy at higher temperatures. Thats why combustion engines work.

Here on Earth, its warm enough for atoms to use thermal energy to overcome the energy barriers to their formation into amino acids.

But out there in space? Its cold and molecules are lazy. They dont have enough energy to climb over the energy barrier.

In order to overcome this, the researchers simply relied on the universes natural penchant for cheating.

Instead of giving the atoms more energy, the universe teleports them past the barrier and pretends like it never happened. This is a wacky quantum process called tunneling.

As Chemistry Worlds Katrina Kramer explains:

Tunnelling is actually a terrible word to use because the term conjures up images of a particle boring its way through a wall. But there is no hole, tunnel or any other type of opening involved.

Instead, we need to use the same currency the field of quantum mechanics deals in: probability. A particle can be described as an oscillating wave, its amplitude representing the probability of finding it in a certain place. When encountering a barrier, this wave doesnt end abruptly. Instead, it continues inside and on the far side of the barrier, albeit with a smaller amplitude.

Basically, life on Earth exists because the universe allows particles to glitch through walls like characters in a poorly-modeled video game world.

The amino acids were made out of were very likely formed in space through ridiculous circumstances before eventually being forged into cosmic masses made of improbable organics.

Per the teams paper:

As demonstrated here, a portion of these organics could be in the form of peptides. At later stages, such dust becomes the building blocks of comets or meteorites. The formed organics could therefore have been delivered to the early Earth during the period of heavy bombardment.

Quantum tunneling might sound like the kind of thing scientists make up when they cant explain what happened, but its actually a phenomenon theyre quite familiar with.

The sun, for example, only shines because enough random particles tunnel past their own energy barriers to cause the chemical reactions necessary to keep it burning.

Life, or at least its building blocks, might not be as rare as we once thought. Unfortunately for us, however,it seems like planets that can support it are.

See the original post here:

Scientists think quantum tunneling in space led to life on Earth - The Next Web

There are few thought experiments in science as famous as Schrdinger's Cat, even though most people couldn't explain it to you if they tried.

It's not that the implications of the thought experiment are opaque. In fact, the implications of the thought experiment are the one thing that almost everyone knows: that Schrdinger's Cat is both alive and dead at the same time.

But what does that even mean? What chain of logic could possibly lead to that kind of result?

Fortunately, you don't need a degree in physics to understand what Schrdinger was getting at with his thought experiment, and even Albert Einstein praisedSchrdinger for devising such a simple illustration of some of the more confusing parts of quantum mechanics.

So, in short, don't worry. The Schrdinger's Cat thought experiment isn't nearly as complicated as many seem to believe, and properly understandingSchrdinger's Cat is an essential part of grasping the fundamental features of the bizarre quantum realm of physics.

ErwinSchrdinger was a Nobel Prize-winning Austrian physicist who was instrumental in developing many of the fundamental aspects of quantum theory.

Other than his well-known thought experiment,Schrdinger is most famous for his wave equation, which is used to calculate the wave function of a quantum system at different points in time.

Even though he played such a large role in its formation,Schrdinger didn't always agree with his fellow quantum theorists. In fact, many of the ideas that they proposed for quantum mechanics sounded preposterous toSchrdinger, especially one of quantum mechanics' most famous features: superposition.

Quantum superposition is a feature of quantum mechanics where a particle can exist in more than one quantum state, and it is only when a particle is measured that its definite state can be determined.

Understandably, this adds a layer beneath physical reality that strikes many people as either counterintuitive or painfully obvious.

On the one hand, it hardly seems revolutionary to say that you can't determine a particle's state until you measure it. You can't determine your height until you measure it either, so what's the big deal?

The difference between the two is that you are a certain height, whether you measure it or not. If your height had the quantum property of superposition, you would not have a definite height at all prior to measurement.

Generally speaking, you would have an entirely even chance of being in any given measurable state, so if we restricted that to just the five-foot range, you would have a 1-in-12 chance of being five feet and one inch tall,five feet and two inches tall, and so on, but you wouldn't be any of those heights until we measured you.

This latter part cuts against our own lived experience since we never encounter something in our day-to-day lives that exist in such a superposition. When you descend in scale enough to be dealing with individual atoms and even smaller particles, not only is superposition possible, it's been verified time and again over the decades.

The Copenhagen Interpretation of quantum mechanics isn't one thing specifically, but an assortment of ideas about quantum theory that are closely associated with two major founders of quantum mechanics, Neils Bohr and Werner Heisenberg.

What matters for us is the idea that Bohr postulated in the 1930s that a quantum particle and the instrument used to measure that particle do not act independently of each other, but rather become inextricably linked in the process of taking the measurement.

This has led to the common generalization that a particle "knows" that it is being watched and responds to the presence of an observer by defining its state so it can be measured.

This directly contradicts very basic principles of classical physics and logic, and it's what so flummoxedSchrdinger that he developed his famous thought experiment to show just how absurd that idea is.

In order to show that a particle can't be linked to the observer on a quantum level,Schrdinger devised the idea of a diabolical device in a box. Inside the box, there isSchrdinger's Cat, as we now know it, but there is also a Geiger counter wired to a hammer.

There is also a sealed glass bottle containing poison gas and a tiny amount of a radioactive substance. Quantumly, that substance can either decay or not decay at any given moment.

If the substance decays, the Geiger counter detects the radiation and triggers the hammer to break the glass bottle, releasing the gas into the box, which would in turn kill the cat.If the substance does not decay, nothing happens and the cat remains alive.

But, because of the principle of superposition, the substance can both decay and not decay, so the Geiger counter is both smashing the bottle and not smashing the bottle, andSchrdinger's cat is both alive and dead, all at the same time.

The Copenhagen interpretation would therefore imply that it isn't until the experiment is observed by opening the box that the quantum state of decay or not decay is decided, so it is only after opening the box that the true fate of the cat inside is settled.

This question is exactly whatSchrdinger was getting at with his thought experiment. The implications of the Copenhagen interpretation simply aren't logical when applied to his cat in a box.

The proposed outcome does not match our reality, and so Schrdinger and other opponents of the Copenhagen interpretation argued that it was straying away from science and entering the world of philosophy and metaphysics.

An important distinction that needs to be made is thatSchrdinger was not saying that quantum superposition isn't real.

He was trying to illustrate that the human observers of the experiment are not the deciding factor, since any interaction with a particle in superposition by just about anything can count as an observation in the quantum sense.

Long before a human ever opens the box, the fate ofSchrdinger's cat had already been decided by the Geiger counter.

Of the Copenhagen interpretation, Einstein, writing toSchrdinger in 1950, said;

this interpretation is, however, refuted, most elegantly by your system of radioactiveatom + Geiger counter + amplifier + charge of gun powder + cat in a box, in which the[quantum wave-function] of the system contains the cat both alive and blown to bits. Is the state of thecat to be created only when a physicist investigates the situation at some definite time?Nobody really doubts that the presence or absence of the cat is something independentof the act of observation.

As Dr. Christopher Baird, an assistant professor of physics at West Texas A&M University writes: 'quantum state collapse is not driven just by conscious observers, and 'Schrodinger's Cat' was just a teaching tool invented to try to make this fact more obvious by reducing the observer-driven notion to absurdity. Unfortunately, many popular science writers in our day continue to propagate the misconception that a quantum state (and therefore reality itself) is determined by conscious observers."

So now you know the real story behindSchrdinger's cat, but don't worry, quantum mechanics is weird enough without having to resort to a feline multiverse.

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What is Schrdinger's Cat and why is everyone trying to kill it? - Interesting Engineering

image:Prof. Tomer Volansky view more

Credit: Tel Aviv University

A new study led by Tel Aviv University researchers demonstrates unprecedented sensitivity to an exciting dark matter candidate. As part of the new NASDUCK (Noble and Alkali Spin Detectors for Ultralight Coherent dark-matter) collaboration, the researchers developed unique innovative quantum technology that enables receiving more accurate information on invisible theoretical particles suspected of being dark matter with ultralight masses. The study was published in the prestigious Advanced Science journal.

The study was led by Prof. Tomer Volansky, research student Itay Bloch from the Raymond & Beverly Sackler School of Physics & Astronomy in the Raymond & Beverly Sackler Faculty of Exact Sciences at Tel Aviv University, Gil Ronen from the Racah Institute of Physics at the Hebrew University, and Dr. Or Katz, formerly of the Weizmann Institute of Science (now from Duke University).

Dark Matter is one of the great mysteries of physics. It composes most of the matter in theuniverse, and it is known to interact through gravity; however, we still know very little of its nature and composition. Over the years, many different theoretical particles have been proposed as good candidates to serve as dark matter, including the so-called axion-like particles.

Prof. Tomer Volansky explains: The interesting thing about axion-like particles is that they can be significantly lighter than any of the matter particles seen around us, and still explain the existence of dark matter, which for years was expected to be significantly heavier. One of the main ways of searching for dark matter is by building a large experiment with lots of mass, waiting until dark matter collides with it or is absorbed in this mass, and then measuring the minute energetic imprint it leaves in its wake. However, if the mass of the dark matter is too small, the energy carried by it is so insignificant that neither the collision nor the absorption effect can be measured. Therefore, we need to be more creative and use other properties of dark matter.

In order to discover these particles, the researchers have designed and built a unique detector in which compressed, polarized xenon gas is used to find tiny magnetic fields. Surprisingly, it turns out that axion-like particles which play the role of dark matter, affect the polarized xenon particles as if it is placed in a weak anomalous magnetic field which can be measured. The innovative technique used for the first time by the researchers, enabled them to explore a new range of dark matter masses, improving previous techniques by as much as three orders of magnitude.

PhD student Itay Bloch adds: This is quite a complex operation, since these particles, if they exist, are invisible. Nevertheless, we have succeeded with this study in constraining the possible properties of axion-like particles, by the very fact that we have not measured them. Several attempts have been made to measure such particles by turning them into particles of light and vice versa. However, the innovation in our study is the measurement through atomic nuclei without relying on an interaction with light, and the ability to search for axion-like particles in masses that were hitherto inaccessible.

The study is based on especially complex mathematical methods taken from particle theory and quantum mechanics and employs advanced statistical and numerical models in order to compare the empirical results with the theory.

Prof. Volansky concludes: After five months of sustained effort, we have presented a new method that expands what we thought was possible with magnetometers; therefore, this is a small but significant step towards finding dark matter. There are many more candidates for dark matter, each with its own quantum properties. However, axion-like particles are among the most interesting options, and if we ever find them, that would be a huge step forward in our understanding of the universe. This experiment was the first of the NASDUCK collaboration, showing the promise that lies in our detectors. I have no doubt that this is just the beginning.

New constraints on axion-like dark matter using a Floquet quantum detector

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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For the first time, new quantum technology demonstrates capabilities that may enable detection of ultralight dark matter - EurekAlert

The present has a special status for us humans our past seems to no longer exists, and our future is yet to come into existence. But according to how physicists and philosophers interpret Einsteins Theory of Relativity, the present isnt at all special. The past and the future are just as real as the present - they all coexist and you could, theoretically, travel to them. But, argues Dean Buonomano, this interpretation of Einsteins theory might have more to do with the way our brains evolved to think of time in a similar way to space, than with the nature of time.

The human brain is an astonishingly powerful information processing device. It transforms the blooming buzzing confusion of raw data that impinges on our sensory organs into a compelling model of the external world. It endows us with language, rationality, and symbolic reasoning, and most mysteriously, it bestows us with consciousness (more precisely it bestows itself with consciousness). But, on the other hand, the brain is also a rather feeble and buggy information processing device. When it comes to mental numerical calculations the most complex device in the known universe is embarrassingly inept. The brain has a hodge-podge of cognitive biases that often lead to irrational decisions. And when it comes to understanding the nature of the universe, we should remember that the human brain was optimized to survive and reproduce in an environment we outgrew long ago, not decipher the laws of nature.

Is Einstein still right?Read moreTo date, the most powerful tool we have devised to overcome the brains limitations is called mathematics. Once in a while an outlier such as Einstein or Schrdinger conjures up equations that allow us to describe and predict the external world, independently of whether the human mind is capable of intuitively understanding those equations. We can plug those equations into a computer, which can then pump out predictions about what will occur when, whether or not we (or the computer) understand those equations.

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Much as chess is beyond the grasp of Schrdingers cat, an intuitive understanding of quantum mechanics is probably beyond the grasp of the human brain.

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Mathematics, however, is mostly agnostic to the interpretation of the equations of modern physics. This is particularly clear in the case of Schrdingers equation, which helped master the quantum world of particles that underlies much of our digital technology. No one can really claim to intuitively understand what a wavefunction actually is, or what it means for two photons two be entangled. Much as chess is beyond the grasp of Schrdingers cat, an intuitive understanding of quantum mechanics is probably beyond the grasp of the human brain.

The equations that comprise the laws of modern physics have proven accurate beyond any reasonable expectation, but when we interpret the equations of relativity and quantum mechanics, we often forget to take into account the inherent limitations, constraints, and biases, of the organ doing the interpreting. This point is particularly relevant in the context of what the laws of physics tell us in regard to the nature of time.

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Under eternalism time-travel is a theoretical possibility, as my past and future selves are in some sense physically real. In contrast, under presentism the notion of time travel is impossible by definition.

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While there is no universally accepted view as to the nature of time, the two main views are referred to as eternalism and presentism. In its simplest form eternalism maintains that the past, present, and future all stand on equal footing in an objective physical sense. The past, present, and future all coexist within what is called the block universe. Under presentism, my local present moment is fundamentally and objectively different from the past and future, because the past no longer exists and the future is yet to exist. Importantly presentism is local, and distinct from the empirically disproven Newtonian notion of absolute time, in which clocks moving at different speeds will remain synchronized. While some have argued that the distinction between eternalism and presentism is a false dichotomy, the fundamental difference between them can be easily captured in the context of time travel. Under eternalism time-travel is a theoretical possibility, as my past and future selves are in some sense physically real. In contrast, under presentism the notion of time travel is impossible by definition, one cannot travel to moments that dont exist.

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It is important to note that relativity does not predict that we live in an eternalist universe, rather it allows for an eternalist universe.

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One of the strongest arguments for eternalism was planted in 1908 by Herman Minkowskis geometric interpretation of Einsteins special theory of relativity. In it, time is represented as one axis in four-dimensional space, and movement of a clock along any of the three spatial dimensions will slow the rate at which it ticksMinkowski bound space and time into spacetime. But any geometric representation of time inevitably corrals the brain to think about time much like spacethinking of past and future moments in relation to now, as being as real as positions to the left and right of here. Indeed geometry, as formalized by Euclid over two thousand years ago was the study of static spatial relationships, and it was likely the first field of modern science because it had the luxury of ignoring time. Einsteins theory of general relativity further cemented the concept of spacetime into physics. But it is important to note that relativity does not predict that we live in an eternalist universe, rather it allows for an eternalist universe. Relativity makes no explicit testable predictions regarding eternalism versus presentism. Indeed, it is far from clear that there are any testable predictions that could prove or disprove eternalism or presentism (other than the emergence of a confirmed time traveler). And if advanced aliens ever came to Earth and assured us that we live in a presentist universe, I dont think anybody would claim that proves relativity is wrong (although presentism does set boundaries on the solutions to the equations of general relativity).

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Contrary to our everyday experiences, when interpreting the laws of physics, perhaps the architecture of the human brain imposes a bias towards eternalism.

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While the laws of physics do not assign any special significance to the present, they are ultimately agnostic as to whether the present may be fundamentally different from the past and future. Why then, despite our clear subjective experience that the present is special, is eternalism the favored view of time in physics and philosophy? Contrary to our everyday experiences, when interpreting the laws of physics, perhaps the architecture of the human brain imposes a bias towards eternalism. Thinking about time as a dimension in which all moments are equally real, better resonates with the brains architecture which readily accepts that all points in space are equally real.

The human brain is unique in its ability to conceptualize time along a mental timeline and engage in mental time travel. We can think about the past and simulate potential futures to degrees that evade the cognitive ability of other animals. It is mental time travel that allows us to engage in species-defining future-oriented activities, such as agriculture, science, and technology development. But how did humans come to acquire this ability? Evidence from linguistics, brain imaging, psychophysics, and brain lesion studies, suggest that the human brain may have come to grasp the concept of time by co-opting older evolutionary circuits already in place to represent and conceptualize space. A common example in the context of linguistics is that we use spatial metaphors for time (it was a long day; I look forward to seeing you). Imaging studies show a large overlap in brain areas associated with spatial and temporal cognition, and people with brain lesions that result in spatial hemineglect (generally characterized by an unawareness of left visual space), often exhibit deficits in mental time travel.

Our brains certainly did not evolve to understand the nature of time or the laws of the physics, but our brains did evolve to survive in a world governed by the laws of physics. Survival, of course, was not dependent on an intuitive grasp of physical laws on the quantum and cosmological scaleswhich is presumably why our intuitions epically fail on these scales. But questions pertaining to the reality of the past and future, fall squarely within the mesoscale relevant to survival. Thus, if one accepts that our subjective experiences evolved to enhance our chances of survival, our subjective experience about the passage of time and the fundamental differences between the present, past, and future, should be correlated to reality. A common counterexample to this point is our incorrect intuitions about the movement of the Earth. However, our incorrect perception that the Earth is static while the sun moves around us, pertains to the cosmological scale and is largely irrelevant to survival.

Empirical evidence from physics should always override our intuitions about the world. Yet in the case of the presentism versus eternalism debate there is actually no empirical evidence for eternalism. But there is some empirical evidence for presentism. Our brains are information processing devices designed to take measurements and make inferences about the physical world. Indeed, on the mesoscopic scale the brain does an impressive job at creating a representation of reality by measuring the physical properties of the world. It measures light, weight, temperature, movement, and time, in order to simulate the world well enough to survive in it. Our subjective experience of color or temperature, help us survive because they are correlated with reality.

I suspect that our subjective experiences regarding the nature of time also evolved because they capture some truth about the nature of the universe.

Perhaps one day objective evidence will emerge that we live in an eternalist universe, and we will understand why our subjective experiences are misleading. But until that day, we should accept our experience that the present is objectively different from the past and future as empirical evidence in favor of presentism.

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Einstein and why the block universe is a mistake - IAI

Europes deep tech sector is having its moment and accounts for a quarter of the blocs start-up ecosystem.

Deep technology is the generic term that covers all tech that is based on tangible engineering innovation or scientific advances. It includes technologies such as artificial intelligence, robotics, quantum computing and blockchain.

Europe is seeking to bolster firms in the sector to compete on the global stage. At the Mobile World Congress in Barcelona, Euronews Next spoke to three deep tech start-ups worth keeping an eye on.

The Swiss start-up is developing a technology that measures your facial expressions, such as eye movement and jaw biting through earbuds and then sends those signals to a small box connected to the device, which sits at the back of your neck.

This Internet of Humans technology uses its closed-loop system which translates brain waves and uploads this data to their cloud. Once processed, these signals can tell us a lot about our state of mind, including levels of tiredness, focus and other cognitive activity.

These health insights are then analysed and can help build knowledge about different mental states, which could ultimately help people hear or sleep better.

The start-up is working with the Japanese pharmaceutical company Takeda and is validating the technology for sleep onset neuromarker detection.

For the moment, the start-up is at the end of its seed stage and is a business-to-business company but its aim is to roll out its products to consumers, so that it could be used in multiple scenarios, including selecting your music playlist based on your mood.

The technology is still in development and health regulation is still needed.

People will look back in 100 years and they will say people died from perfectly curable diseases because they just didn't know about it, IDUN Technologies chief executive officer and co-founder Simon Bachman told Euronews Next.

I understood that we need to get better in preventative health and for preventative health you need a technology which is accessible by healthy people, he said.

However, he said one of the largest limitations of the medtech area and healthcare area is because regulation means there's a huge barrier to get into the sector.

Bachman said he welcomes regulation and the company has its own neuroethics committee that discusses issues of data sharing. He also said the company is actively participating in the dialogue on how neurotechnology could and should be regulated and is speaking to policymakers.

As for being a European start-up, Bachman said there is literally no drawback.

Europe is the place to be because we are living in a connected world. And you know, the talents in Switzerland, especially, but also in Europe.

Oxford Quantum Circuits: the supercomputer

Quantum computing is another sector that is taking off in Europe. It works by using quantum physics to create new ways of computing.

Quantum computers typically have an edge over regular computers in situations where there are lots of possible combinations, as they can consider these simultaneously.

Quantum computing can be used across multiple sectors, including by businesses for risk analysis, governments for cybersecurity and the pharmaceutical industry.

One start-up based in the United Kingdom that is making strides with this technology is Oxford Quantum Circuits.

We are a pure-play, quantum computers service company, which basically means we build quantum computers and then operate them in the hands of customers so that they can solve some of the world's most challenging problems using quantum to create this quantum-enabled future, Ilana Wisby, co-founder and CEO told Euronews Next.

The company launched this week with Amazon Web Services Amazon Braket so that for the first time quantum computing is now available by public cloud via Amazon Braket in Europe.

Wisby said this was incredibly important because there's a lot of their customers that are already accessing quantum computing, but they haven't had European hours for uptime and they haven't had European data protection.

So these are things that we can now provide, she said, adding that they have now been able to have private customers work with them directly, which opens a much larger market for them.

The Greek start-up MAGOS is developing a hardware and software solution to revolutionise the interaction of users within the digital environment. It has produced an exoskeleton glove that allows you to touch and feel in the virtual world.

The wearable glove-type product is connected with a PC and digitises the motions in your hand with very high accuracy of how the fingers move.

The company uses unique sensors which are connected to every joint and capture every movement and feeling. This technology could be used by clinicians in training to perform procedures remotely and give data to health care providers from a distance, which may revolutionise hand rehabilitation.

We see that the computing devices of the future will be the headsets the TED model displays for augmented reality and or any product that the current hardware will evolve to, Magos CEO and founder Greg Agripolous told Euronews Next.

Though the technology is revolutionary, it is hard to compete as a European start-up, he said.

We have some competitors from the US. The market there is much more mature and corporate and there is more investment in technologies.

And the funds are available in the US way more than in Europe, so we are struggling a lot.

However, Agripolous noted that despite those difficulties the start-up has managed to attract EU innovation funds and is attracting customers from the US.

Can Europe compete?

Europe is trying to bolster its tech ecosystem to rival those of the United States and China with a new initiative.

The European Start-up Nation Alliance (ESNA) was first announced during the Portuguese Presidency of the Council of Europe in November last year.

ESNA is in charge of a new standard for start-ups across the bloc and will compile best practices as well as provide technical support and monitor start-up progress.

It also has the ambitious aim to double the blocs number of unicorns by 2030.

Member states have pledged commitments to ESNA, including France, which has committed to facilitating the creation of 10 to 20 late-stage investment funds with at least 1 billion under management and a boost in deep-tech financing.

At the Mobile World Congress, the digital and economic ministers of Spain, Portugal and Austria met to discuss how ESNA may shake up the blocs start-ups.

Too much fragmentation is another issue the alliance wants to solve.

There are 27 different member states and legal frameworks (...), which is different from the USs single market, said Andr de Arago Azevedo, Portugals Secretary of State for Digital Transition.

Pere Duran, the director of the start-up platform 4YFN (four years from now) said data protection was another issue for the bloc.

I believe that there are several challenges, and one of them is to be able to compete with ecosystems such as China and the US, who probably do not have as many regulations as we do here on the tax areas and data protection," he told Euronews Next.

But Duran said the start-up scene in Europe is "really thriving" and investment in the bloc's start-ups is reaching record levels.

More than 100 billion was invested in European tech last year so it's a very good moment to be a digital entrepreneur in Europe, he told Euronews Next.

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Deep tech: Three mind-blowing start-ups to watch as Europe aims to double its unicorns - Euronews

Here at Big Think, we are incredibly lucky to have some of the greatest minds writing about the biggest questions in the Universe. In this case, the question is even bigger than the Universe.

We invited two astrophysicists Dr. Ethan Siegel (Starts with a Bang columnist) and Dr. Adam Frank (13.8 columnist) to engage in a debate over one of the hottest topics in astrophysics: Is the Multiverse real?

Cosmic inflation and quantum field theory both describe the Universe.Cosmic inflation, first put forth in 1980, tells us what the Universe was like prior to the hot Big Bang in order to set it up with the conditions that we observe. Put simply, it states that before the Universe was filled with matter and radiation, it was filled with some sort of energy that was inherent to the fabric of space itself, which caused the Universe to expand in a relentless, exponential fashion. Then, at some point, inflation ended, transitioning that energy inherent to space into particles and giving rise to the hot Big Bang.

Because the Universe is inherently quantum in nature, that means we should expect that whatever inflation is, it has a nature that is consistent with quantum field theory our best and most powerful description of the Universe of particles. All the things that come along with quantum physics, like Heisenberg uncertainty and the existence of quantum fluctuations, must apply to inflation as well.

So, what happens when you put inflation and quantum field theory together? You get a series of predictions, many of which have been borne out by observations. Inflation is now widely regarded as the origin of our Universe, and those observations narrow down which classes of inflationary models remain viable. Accepting cosmic inflation and quantum field theory is the scientific consensus right now, meaning it can be considered our starting point upon which we build.

If cosmic inflation and quantum field theory are both correct, then the Multiverse arises as an inevitable consequence of the two, combined.The easiest way to picture inflation is that its a ball at the top of a very flat plateau. The ball can roll slowly in any direction, but so long as it remains atop the plateau, inflation continues. It is only when the ball rolls off the plateau and into the valley below that inflation comes to an end, transitioning into a Universe dominated by particles: matter and radiation, which signifies the start of the hot Big Bang.

So where does the Multiverse come from?

One of the properties of quantum physics is that the position of a particle at any given time isnt deterministic but follows a probability distribution. Moreover, the wavefunction that describes that probability distribution spreads out over time. You can visualize this, instead of as a ball, as the ripples generated by a ball dropped into a pond.

Now, heres where it gets interesting: We have two things competing against one another. On the one hand, we have the speed of the rolling ball, and on the other hand, we have the speed of the ripples that propagate outward. If the ball rolls faster than the ripples propagate, inflation can end everywhere at once, and there will only be one Universe bigger than the observable Universe that we can see, but still finite in size and all connected.

But if the ripples propagate faster than the ball rolls, then you will have regions where the ripples fall off the plateau, and in those regions, you get a hot Big Bang. But, you will also have regions where the ripples take you closer to the center of the plateau, and in those regions, inflation continues. What you wind up with, in this latter scenario, are regions where inflation ends and you get a hot Big Bang, but separated by regions where inflation continues for longer. As time goes on, you will get more and more regions where inflation ends and the hot Big Bang ensues, but also evermore regions where inflation continues.

Those regions of space where inflation end and the hot Big Bang begins are each their own, independent Universe, and together, they make up a Multiverse. We may not be able to measure these other Universes, at least not just yet, but theres every reason to expect that if inflation and quantum field theory are both correct, then the Multiverse inevitably exists.

Ethan does a great job of summarizing both inflation and its connection to the Multiverse. So, a good place to start is to note that in my original piece, I was criticizing the idea of the Multiverse but not, necessarily, inflationary cosmology. There are reasons why positing a brief period of expansion-on-steroids (that is, inflation) can be useful. The problem comes if the only way you can make it work is adding an infinite number of observable Universes.

It is important, from my viewpoint, to understand what is happening with inflation theory because it is not really a theory the way, say, electromagnetism or quantum mechanics is. It is not what I would call a theory with a capitol T, featuring endless points of experimental verification such that its true form has been nailed down and locked tight.

Instead, it is a class of theories with lots of wiggle room for individual instantiations. That wiggle room has led to many discussions about the ability of the theory to ever be falsifiable because, no matter what new data is gathered, there will always be a version of it that can be designed to slip through the new constraint. (I note there are also discussions about the continued need for fine tuning with inflation theory.)

Inflation does have a few places where it is consistent with observations like the spectrum of perturbations that get propagated forward in time to become large-scale cosmic structure. That is indeed very good. But it is a far cry from the kind of validation we have of, say, the Standard Model of Particle Physics, which has been verified six ways to Sunday.

This is an important point because inflation takes physics we understand at way, way lower energy scales and extrapolates them into very different kinds of conditions. There are many orders of magnitude between the quantum field theory we understand and the inflationary domains of spacetime. This is one reason why there are so many flavors of inflation. We dont even know what physical field drives inflation. Its particle is just called the inflaton, and there is a lot of latitude available for theorists in making up its properties. Now this, by itself, is not a problem. Speculation and extrapolation are part of what physicists do.

But

If, in the process of extrapolating to wildly extreme regimes, you end up in dangerous (from the point of view of the epistemological underpinnings of science) territory, then I think you need to step back and ask about what might have gone wrong.

This is exactly what happens with eternal inflation and the Multiverse. A theory we understand in one regime (much lower energy particle accelerators) gets stretched into a very different one (10-36 of a second after the Big Bang). That extrapolation solves some problems (but not others), but it all comes at a strange cost. That cost is what I call ontological exuberance.

It is possible that the only way the inflation extrapolation works is to accept an infinite number of Universes that you may never ever be able to observe. But that is not good. And it is not like anything else thats happened in the history of physics. Sure, we cannot observe what is inside a black hole; and yes, we have dark matter that we cannot see; and yes, there are the parts of our Universe beyond the light horizon. But in the case of dark matter (if it exists), then we can at least learn a lot about it in bulk based on the detailed influences it exerts on the luminous matter we can see. And as for the insides of event horizons, I am not forced to accept infinite numbers of Universes as the price for accepting General Relativity. Same goes for what lies beyond the observable Universe.

To summarize, I would argue that inflation has some attractive features, but it simply does not stand as the kind of scientific edifice (in terms of having many, many points of contact with observation) that should force us to accept the Multiverse. If that is really the only choice, then its the assumptions, from soup to nuts, that went into the whole extrapolation enterprise that should be re-examined. Humility in science is a good thing.

Adams response contains some interesting food-for-thought, but there is a dubious logical gambit in there at the core of his argument, which can be paraphrased this way: We dont know everything, therefore how can we trust anything? In any scientific endeavor, you absolutely must be careful about what assumptions you are making that go beyond the limit of what you can observe and/or verify, but you must also not ignore the very generic predictions that show up independently of the assumptions that you make.

What he asserts about inflation is true in the sense that we do not know absolutely everything about it, including what the exact properties of the specific model of inflation are that describes our Universe. However, I would dispute his assertion that you can cook up any model you like to give you any properties you like, as many predictions are model-independent. In other words, no matter what model of inflation you choose to work with, the same behavior always emerges. These are the things we can trust, most confidently, about what inflation predicts.

So, what are the model-independent predictions? Here are some of them:

Over the past ~40 years, we have put these predictions to the test and verified the first four of them. Currently, we are unable to measure the Universe to the necessary sensitivity to detect the final two.

But another prediction and yes, it is a prediction that inevitably comes out of inflation is this: if you concoct a model of inflation that agrees with observations, specifically by allowing enough inflation to occur to give the Universe the properties we observe it to have, then inflation always continues in more regions of space than it ends. Because the inflating portions of space grow exponentially, and the non-inflating portions grow at a much slower rate (as a power law), there is always more inflating space than regions where inflation ends, and that inflating space separates and drives apart those other regions.

Once inflation begins, anywhere in the Universe, this scenario (illustrated above) is inescapable. That is why there is a Multiverse, and why the Multiverse is a generic prediction of inflation. Quantum gravity will not save you, since this occurs at energy scales much lower than those where quantum gravity is important. Moreover, Adams appeal to the physics of very high energy scales will not save his argument, since these properties of inflation have been shown to be energy-scale independent.

In other words, yes, inflation gives you some wiggle room in many ways, but you cannot wiggle out of the Multiverse. The only way out, as Adam says, is to postulate a Rumsfeldian unknown unknown to save you. And while that is always possible in any endeavor, I think it is far preferable to draw your best conclusions based on what is known to the limits of our best knowledge at the time. To retort with a quote from the late Macho Man Randy Savage, You may not like it, but accept it.

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Is the Multiverse real? Two astrophysicists debate - Big Think