Tag Archives: calculations

Is Time a Construct of Universal Calculations?

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What if the universe is just one big computer?

What if the universe was just one big computer?

NASA/ESA/J. Lee and pro500/Shutterstock

Below is an excerpt from our Lost in Space and Time newsletter. Every month, we share fascinating insights from around the globe. You can subscribe to Lost in Space and Time here.

My colleagues and I often joke about time’s illusion. “Oh, did I miss the deadline?” But what if time itself isn’t real? How can 40 years feel like mere moments? If extraterrestrial observers were to gaze at Earth now, would they witness an age of dinosaurs or merely an expanse of molten rock? Clearly, our perception of time is complex.

Yet, there’s a profound truth in this humor. It’s not that time is fictional; rather, our understanding of it is superficial. This sentiment resonates with physicists and philosophers who have contemplated time for centuries. Numerous theories exist, yet a definitive explanation remains elusive.

I posed this question to Stephen Wolfram, an esteemed physicist and computer scientist who has developed influential computational tools. His ambitious initiative, the Wolfram Physics Project, aims to redefine physics through computation instead of the conventional mathematical frameworks. This project has stirred debate within the scientific community. Wolfram’s premise—viewing the universe as one massive computer—could potentially unravel the mysteries of time, its forward motion, and our inability to foresee the future. I spoke with him to delve deeper into this concept.

Leah Crane: What is time?

Stephen Wolfram: Time is fundamentally an act of calculation.

Leah Crane: And that’s a wrap! Have a great day.

Time has puzzled physicists and philosophers for centuries

Vernon Leach / Alamy

Seriously, can you elaborate?

The perception of time is fundamentally the ongoing calculation of the universe’s continuous state.

Is it comparable to stacking images in a flipbook to simulate movement?

In a manner, yes, but it’s more intricate. Each state is computed sequentially from the preceding state over time. A question arises: if clear rules govern these computations, why can’t we predict outcomes? Why do we experience the relentless flow of time? The answer lies in the concept I’ve termed computational irreducibility.

What does irreducibility mean, and how does it inhibit time travel or future predictions?

Knowing a system’s foundational rules doesn’t guarantee its predictability. Traditionally, in mathematical sciences, one can derive future states from these rules. However, for many systems, the complexity of the calculations necessitates running each step, revealing the evolution of the system over time. Irreducible calculations compel you to traverse every step; shortcuts are non-existent.

Can you provide a tangible example of a computation that’s not reducible?

Consider calculating the digits of pi. Although there’s a defined method, you cannot reach the 1200th digit without calculating the preceding 1199 digits.

So it’s akin to navigating a staircase in the dark, where each step reveals the next?

Precisely. Climbing unpredictable stairs in the dark presents challenges. Predictability is integral to our experiences and how we navigate the world.

Thus, irreducible calculations resemble climbing a complex staircase in darkness, requiring focus without skipping steps and precluding time travel and future predictions. Is human nature inherently bounded?

Human observers have limited computational capabilities. For instance, deciphering an encrypted message demands exhaustive trials to find the plaintext. In scenarios involving computationally irreducible processes, we are unable to execute the entirety of calculations; our cognitive resources are finite. Predicting what occurs after a billion steps is simply beyond our mental capacity.

When calculating time, you cannot skip some steps

Alex Lynch / Alamy

If I had enhanced computational prowess, could I predict the future?

Should a computer execute computations faster than the universe itself, then theoretically, yes. However, our current computers are constructed from the universe’s materials, limiting their predictive capabilities.

Is this framework deterministic, where everything is entirely predetermined? How does humanity and free will fit in?

In deterministic contexts, knowing a system’s rules can imply predictability. However, if a computation is irreducible, the only way to ascertain outcomes is through executing the computation. You cannot outrun the system; experiencing it is essential for understanding.

This presents a duality: it illustrates the limits of science but also highlights the significance of experiencing time. The passage of time indicates that we engage in irreducible calculations, imbuing our experiences with meaning.

Your insights suggest our existence transcends the notion of superdeterminism. Even if free will is debatable, this ambiguity is vital to our experience?

Even within frameworks that suggest determinism, the nuances of decision-making remain significant. We might be subject to rules, yet our choices hold weight. Simple rules can yield complex outcomes. Imagining free will independent of existing laws paves the way for the universe to function arbitrarily. Failure in scientific inquiry would follow from such randomness. Thus, to establish consistent laws, we must acknowledge their inherent limitations.

Conclusively, if foundational laws govern reality, does the concept of free will lose its relevance?

Indeed, once definitive laws govern the universe, the broader concept of free will dissipates. The intriguing inquiry remains: why do we perceive free will? Computational irreducibility might elucidate this; predicting future actions undermines the perception of agency, portraying us as passengers within a predetermined narrative.

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Source: www.newscientist.com

Challenging Calculations: Quantum Computers May Struggle with ‘Nightmare’ Problems

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Certain problems remain insurmountable for quantum computers.

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Researchers have uncovered a “nightmare scenario” computation tied to a rare form of quantum material that remains unsolvable, even with the most advanced quantum computers.

In contrast to the simpler task of determining the phase of standard matter, such as identifying whether water is in a solid or liquid state, the quantum equivalent can prove exceedingly challenging. Thomas Schuster and his team at the California Institute of Technology have demonstrated that identifying the quantum phase of matter can be notably difficult, even for quantum machines.

They mathematically examined a scenario in which a quantum computer receives a set of measurements regarding the quantum state of an object and must determine its phase. Schuster mentioned that this is not necessarily an impossible task, but his team has shown that a considerable number of quantum phases of matter—such as the complex interactions between liquid water and ice, including unusual “topological” phases that exhibit strange electrical currents—might necessitate quantum computers to perform computations over extremely protracted periods. This situation mirrors a worst-case scenario in laboratory settings, where instruments may need to operate for billions or even trillions of years to discern the characteristics of a sample.

This doesn’t imply that quantum computers are rendered obsolete for this analysis. As Schuster noted, these phases are unlikely to manifest in actual experiments involving materials or quantum systems, serving more as an indicator of our current limitations in understanding quantum computers than posing an immediate practical concern. “They’re like nightmare scenarios. It would be quite unfortunate if such a case arose. It probably won’t happen, but we need to improve our comprehension,” he stated.

Bill Fefferman from the University of Chicago raised intriguing questions regarding the overall capabilities of computers. “This might illuminate the broader limits of computation: while substantial speed improvements have been realized for specific tasks, there will inevitably be challenges that remain too daunting, even for efficient quantum computers,” he asserted.

Mathematically, he explained, this new research merges concepts from quantum information science employed in quantum cryptography with foundational principles from materials physics, potentially aiding progress in both domains.

Looking ahead, the researchers aspire to broaden their analysis to encompass more energetic or excited quantum phases of matter, which are recognized as challenging for wider calculations.

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Source: www.newscientist.com

Webb confirms Hubble’s calculations of distance

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New observations by NASA/ESA/CSA’s James Webb Space Telescope confirm previous measurements by the NASA/ESA Hubble Space Telescope of the distances between nearby stars and galaxies, and confirm measurements of the universe’s mysterious expansion. Provide critical cross-checking to address discrepancies. This contradiction, known as the Hubble tension, remains unexplained by even the best cosmological models.

This artist’s impression shows the evolution of the universe, starting with the Big Bang on the left and continuing with the emergence of the Cosmic Microwave Background. The formation of the first stars ends the Dark Ages of the universe, followed by the formation of galaxies. Image credit: M. Weiss / Harvard-Smithsonian Center for Astrophysics.

“The discrepancy between the observed rate of expansion of the universe and the predictions of the Standard Model suggests that our understanding of the universe may be incomplete,” said Nobel laureate and Johns Hopkins University professor Adam Riess. “There is,” he said.

“Now that NASA’s two flagship telescopes are confirming each other’s discoveries, we must take this issue very seriously. It’s a challenge, but it’s a It’s also a great opportunity to learn more.”

The new research builds on Professor Rees’ Nobel Prize-winning discovery that the expansion of the universe is being accelerated by a mysterious dark energy that permeates the vast expanses of space between stars and galaxies.

The authors used the largest sample of Webb data collected during the first two years of the universe to test the Hubble telescope’s measure of the rate of expansion of the universe, a number known as the Hubble constant.

They used three different methods to measure the distance to the galaxy where the supernova occurred, using a method previously measured by the Hubble telescope and known to provide the most accurate “local” measurement of this number. We focused on the distance that is being

Observations from both telescopes were in close agreement, revealing that Hubble’s measurements were accurate and eliminating inaccuracies large enough to attribute the tension to Hubble’s errors.

Still, the Hubble constant remains a mystery. This is because measurements based on current telescopic observations of the universe produce higher values ​​compared to projections made using the standard model of cosmology. The Standard Model is a widely accepted framework for how the universe works, calibrated with cosmic microwave background data. Weak radiation left over from the Big Bang.

The Standard Model Hubble constant is approximately 67-68 km/sec per megaparsec, but measurements based on telescope observations typically yield higher values ​​of 70-76, with an average of 73 km/sec/megaparsec.

This discrepancy has puzzled cosmologists for more than a decade. A difference of 5 to 6 kilometers per second per megaparsec is too large to be explained solely by deficiencies in measurement and observation technology.

Webb’s new data eliminates significant bias in Hubble’s measurements, so the Hubble tension could be due to unknown factors or gaps in cosmologists’ understanding of physics that have yet to be discovered.

“Webb’s data represent the first high-definition view of the universe, greatly improving the signal-to-noise ratio of the measurements,” said Xiang Li, a graduate student at Johns Hopkins University. .

This image, taken with the Nicholas U. Mayall 4-meter telescope, shows the spiral galaxy Messier 106. Two dwarf galaxies (NGC 4248 in the lower right and UGC 7356 in the lower left) also appear in the image. Image credits: KPNO / NOIRLab / NSF / AURA / New Mexico State University MT Patterson / University of Alaska Anchorage TA Chancellor / M. Zamani & D. de Martin.

The astronomers used the known distance to the spiral galaxy Messier 106 (also known as M106 or NGC 4258) as a reference point to cover roughly one-third of Hubble’s total galaxy sample.

Despite the small dataset, they achieved impressive accuracy, showing less than 2% difference between measurements. This is much smaller than the approximately 8-9% size of the Hubble tension mismatch.

In addition to analyzing pulsating stars called Cepheid variable stars, the gold standard for measuring distances in the universe, they cross-checked measurements based on the brightest red giant stars in the same galaxy as carbon-rich stars. .

All galaxies observed by Webb with supernovae yielded a Hubble constant of 72.6 km per second per megaparsec. This is about the same as the 72.8 km per second per megaparsec that Hubble found for the very same galaxy.

“One possible explanation for the Hubble tension is that something was missing in our understanding of the early universe, such as a new component of matter that unexpectedly bombarded the universe after the Big Bang, nascent dark energy. I guess so,” Johns said. Mark Kamionkowski, a cosmologist at Hopkins University, was not involved in the study.

“And there are other ideas that might do the trick, like interesting dark matter properties, exotic particles, changing electron masses, or primordial magnetic fields. Theorists have a right to be pretty creative. It is.”

of result Published in astrophysical journal.

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Adam G. Reese others. 2024. JWST validates HST distance measurements: Supernova subsample selection explains differences in JWST estimates of local H0. APJ 977, 120; doi: 10.3847/1538-4357/ad8c21

Source: www.sci.news