Tag Archives: theoretical

Calculating the Likelihood of Intelligent Life in the Universe and Beyond: A New Theoretical Model

Posted on by
Reply

In 1961, American astrophysicist and astrobiologist Dr. Frank Drake multiplied several factors to estimate the number of intelligent civilizations in the Milky Way that could make their presence known to humans. I devised an equation. More than 60 years later, astrophysicists have created a different model that focuses instead on conditions created by the accelerating expansion of the universe and the amount of stars forming. This expansion is thought to be caused by dark energy, which makes up more than two-thirds of the universe.

Artistic impression of the multiverse. Image credit: Jaime Salcido / EAGLE collaboration.

“Understanding dark energy and its impact on our universe is one of the biggest challenges in cosmology and fundamental physics,” said Dr. Daniele Solini, a researcher at Durham University’s Institute for Computational Cosmology. .

“The parameters that govern our universe, such as the density of dark energy, may explain our own existence.”

Because stars are a prerequisite for the emergence of life as we know it, the team’s new model predicts the probability of intelligent life arising in our universe, and in a hypothetical multiverse scenario of different universes. could be used to estimate the

The new study does not attempt to calculate the absolute number of observers (i.e. intelligent life) in the universe, but instead calculates the relative probability that a randomly chosen observer will inhabit a universe with certain properties. will be considered.

It concludes that a typical observer would expect to experience significantly greater densities of dark energy than seen in our Universe. This suggests that its ingredients make it a rare and unusual case in the multiverse.

The approach presented in this paper involves calculating the rate at which ordinary matter is converted into stars for different dark energy densities throughout the history of the universe.

Models predict that this proportion would be about 27% in a universe where star formation is most efficient, compared to 23% in our universe.

This means that we do not live in a hypothetical universe where intelligent life has the highest probability of forming.

In other words, according to the model, the values ​​of dark energy density that we observe in the Universe do not maximize the potential for life.

“Surprisingly, we found that even fairly high dark energy densities can still coexist with life. This suggests that we may not be living in the most likely universe. ,” Dr. Solini said.

The model could help scientists understand how different densities of dark energy affect the structure of the universe and the conditions for life to develop there.

Dark energy causes the universe to expand faster, balancing the pull of gravity and creating a universe that is capable of both expansion and structure formation.

But for life to develop, there needs to be areas where matter can aggregate to form stars and planets, and conditions need to remain stable for billions of years to allow life to evolve.

Importantly, this study shows that the astrophysics of star formation and the evolution of the large-scale structure of the universe combine in subtle ways to determine the optimal value of dark energy density required for the generation of intelligent life. It suggests that.

“We will use this model to investigate the emergence of life across different universes and reinterpret some fundamental questions we ask ourselves about our own universe,” said Lucas Lombreiser, professor at the University of Geneva. It will be interesting to see if there is a need.”

of study Published in Royal Astronomical Society Monthly Notices.

_____

Daniele Solini others. 2024. Influence of the cosmological constant on past and future star formation. MNRAS 535 (2): 1449-1474;doi: 10.1093/mnras/stae2236

Source: www.sci.news

Theoretical astrophysicists debate the generation of gravitational waves during warp drive collapse

Posted on by
Reply

The basic idea of ​​a warp drive is that rather than directly exceeding the speed of light in a local frame of reference, a “warp bubble” contracts space-time in front of it and expands it behind it, allowing travel over distances faster than the speed of light as measured by a distant observer.

Craft othersWe propose a formalism for the dynamical study of warp drive spacetime and generate the first fully consistent numerical relativistic waveforms for the collapse of a warp drive bubble.

Although warp drive has its origins in science fiction novels, according to Miguel Alcubierre, an astrophysicist at the University of Wales, warp drive is explained in detail in the general theory of relativity. Be the first to propose A space-time metric that supports faster-than-light travel.

Real-world implementation has many practical barriers, such as the need for a special type of material that has negative energy, but computationally, given an equation of state describing the material, it is possible to simulate changes over time.

In a new study, theoretical astrophysicists investigated the signatures that could result from a “containment failure” of a warp drive.

“Warp drives are purely theoretical, but they are clearly described in Einstein's general theory of relativity, and numerical simulations allow us to explore the effects of warp drives on space-time in the form of gravitational waves,” said Dr Katie Clough, researcher at Queen Mary, University of London.

“The results are fascinating: the warp drive collapse produces a unique gravitational wave burst — a ripple in space-time that can be detected by gravitational wave detectors that typically target merging black holes and neutron stars.”

“Unlike chirp signals from merging objects, this signal is a short, high-frequency burst that would be undetectable by current detectors.”

“But there may be higher frequency devices in the future, and although the money hasn't been put into those devices yet, the technology exists to build them.”

“This raises the possibility that we could use these signals to look for evidence of warp drive technology, even if we can't build it ourselves.”

“In our study, the initial shape of spacetime is the warp bubble described by Alcubierre,” said Dr Sebastian Kahn, a researcher at Cardiff University.

“Although we demonstrate that an observable signal could, in principle, be found by future detectors, the speculative nature of this work is not sufficient to drive instrument development.”

The authors also take a detailed look at the energy dynamics of a collapsing warp drive.

In this process, waves of negative energy matter are released, followed by alternating waves of positive and negative energy.

This complex dance results in a net increase in energy throughout the system and, in principle, could provide another signature of collapse if the emission waves interacted with ordinary matter.

“This is a reminder that theoretical ideas can inspire us to explore the universe in new ways,” Dr Clough said.

“I'm skeptical that we'll see anything, but I think it'll be interesting enough to be worth a look.”

“For me, the most important aspect of this work is the novelty of accurately modelling the dynamics of negative energy space-time and the possibility that the technique can be extended to physical situations that could help us better understand the evolution and origin of the universe or processes at the centre of black holes,” said Professor Tim Dietrich of the University of Potsdam.

“While warp speed may still be a long way away, this research is already pushing the boundaries of our understanding of extra-dimensional space-time and gravitational waves.”

“We're going to try different models of warp drive to see how that changes the signal.”

Team paper Published online Open Astrophysics Journal.

_____

Katie Clough othersThe year is 2024. A phenomenon no one has seen before: gravitational waves caused by warp drive collapse. Open Astrophysics Journal 7;doi:10.33232/001c.121868

Source: www.sci.news

CERN researchers direct attention towards theoretical magnetic monopole

Posted on by
Reply

American theoretical physicist Joseph Polczynski once said that the existence of magnetic monopoles is “one of the safest bets you can make about physics that has yet to be seen.” In the search for these particles that have magnetic charges and are predicted by several theories that extend the standard model, Moedal (Monopole and Exotic Detectors at the LHC) Although the collaboration has yet to prove Polczynski correct, its latest discovery represents a major advance. The new results narrow the search window for these hypothetical particles.

Generation of monopole pairs by Schwinger mechanism. Image credit: MoEDAL Collaboration / CERN.

At CERN's Large Hadron Collider (LHC), interactions between protons or heavy ions can produce pairs of magnetic monopoles.

In collisions between protons, protons can be formed from a single virtual photon (Dorrell-Yang mechanism) or from the fusion of two virtual photons (photon fusion mechanism).

Through a process called the Schwinger mechanism, pairs of magnetic monopoles can also be generated from the vacuum of huge magnetic fields produced by near-miss collisions of heavy ions.

Since starting data acquisition in 2012, MoEDAL has achieved several firsts, including conducting the first search for magnetic monopoles produced by photon fusion and Schwinger mechanisms at the LHC. Ta.

inside First part of the latest researchMoEDAL physicists explored monopoles and highly charged objects (HECOs) produced via the Dorell-Yang mechanism and the photon fusion mechanism.

This search was based on proton-proton collision data collected during Experiment 2 at the LHC using the complete MoEDAL detector for the first time.

The complete detector consists of two main systems that sense magnetic monopoles, HECO, and other highly ionizing virtual particles.

First, magnetic monopole and HECO trajectories can be permanently registered without background signals from standard model particles. The second system consists of an approximately 1-ton capture volume designed to capture magnetic monopoles.

Although the researchers did not find any magnetic monopoles or HECOs in their latest scan of the trapping volume, the masses and production rates of these particles were determined for different values ​​of particle spin, a unique form of angular momentum. limits have been set.

For magnetic monopoles, a mass limit of 1 to 10 times the Dirac charge (gD), the basic unit of magnetic charge, is set, excluding the existence of monopoles with masses as high as about 3.9 trillion electron volts (TeV). I did. .

For HECO, a mass limit was established for charges from 5e to 350e, where e is the electronic charge, and the presence of HECO with masses in the range up to 3.4 TeV was excluded.

“MoEDAL's search reach for both monopoles and HECOs allows the collaboration to explore vast swaths of the theoretical 'discovery space' for these hypothetical particles,” said a spokesperson for the MoEDAL collaboration. said Dr. James Pinfold.

in their second studyMoEDAL scientists focused on searching for monopoles produced via the Schwinger mechanism in heavy ion collision data collected during LHC Experiment 1.

In a unique effort, we scanned a decommissioned section of the CMS experimental beam pipe for trapped monopoles instead of the trapping volume of the MoEDAL detector.

Again, the team found no monopoles, but set the strongest mass constraints yet for Schwinger monopoles with charges between 2 gD and 45 gD, ruling out the existence of monopoles with masses up to 80 GeV. did.

“A crucial aspect of the Schwinger mechanism is that the production of complex monopoles is not suppressed compared to the production of elementary monopoles, as is the case with Dorell-Yang and photon fusion processes,” Pinfold said. Ta.

“Therefore, if monopoles are composite particles, this and the previous Schwinger monopole search may have been the first ever chance to observe monopoles.”

_____

Moedal collaboration. 2024. Searching for highly ionized particles in pp collisions in LHC Run-2 using the Full MoEDAL detector. arXiv: 2311.06509

B. Acharya other. 2024. MoEDAL explores magnetic monopoles generated by the Schwinger effect in CMS beam pipes. arXiv: 2402.15682

Source: www.sci.news

Astronomers make breakthrough discovery in planet formation, conflicting with theoretical predictions

Posted on by
Reply

Recent observations of the young star DG Taurus reveal a smooth protoplanetary disk in which no planets have yet formed, suggesting that it is on the brink of this process. The findings show unexpected dust grain growth patterns and provide new insights into the early stages of planet formation. Credit: SciTechDaily.com

Astronomers have become very good at finding signs of planet formation around stars. However, to fully understand planet formation, it is important to examine cases where this process has not yet begun.

Looking for something and not finding it can sometimes be even more difficult than finding it, but new detailed observations of the young star DG Taurus reveal that the planet is a smooth protoplanet with no signs of planet formation. It was shown that it has a system disk. This lack of detected planet formation may indicate that DG Taurus is on the eve of planet formation.

Image of radio radiation intensity from a disk near DG Taurus observed with ALMA. Rings have not yet formed within the disk, suggesting that planets are about to form.Credit: ALMA (ESO/National Astronomical Observatory/NRAO), S. Obashi et al.

Protoplanetary disk and planet growth

Planets form around protostars, which are young stars that are still forming, in disks of gas and dust known as protoplanetary disks. Planets grow so slowly that it is impossible to observe their evolution in situ. Therefore, astronomers observe many protostars at slightly different stages of planet formation to build theoretical understanding.

This time, an international research team led by Satoshi Ohashi of the National Astronomical Observatory of Japan (NAOJ) has developed the Atacama Large Millimeter/Submillimeter Array (alma telescope) will conduct high-resolution observations of the protoplanetary disk surrounding the relatively young protostar DG Taurus, located 410 light-years away in the direction of Taurus. The researchers found that DG Taurus has a smooth protoplanetary disk and no rings that would indicate planet formation. This led the research team to believe that the DG Taurus system could begin forming planets in the future.

Unexpected discoveries and future research

The researchers found that during this pre-planetary stage, dust particles are within 40 astronomical units (about twice the size of Earth’s orbit). Uranus The radius of the central protostar is still small, but beyond this radius the dust particles begin to grow, which is the first step in planet formation. This goes against the theoretical expectation that planet formation begins inside the disk.

These results provide surprising new information about dust distribution and other conditions at the beginning of planet formation. Studying more examples in the future will further deepen our understanding of planet formation.

Reference: “Dust concentration and particle growth in the smooth disk of a DG tau protostar revealed by ALMA triple-band frequency observations” Satoshi Ohashi, Munetake Momose, Akiraka Kataoka, Aya Higuchi E, Takashi Tsukagoshi, Takahiro Ueda, Claudio Codella, Linda Podio, Tomoyuki Hanawa, Nami Sakai, Hiroshi Kobayashi, Satoshi Okuzumi, Hidekazu Tanaka, August 28, 2023, of astrophysical journal.
DOI: 10.3847/1538-4357/ace9b9

This research was funded by the Japan Society for the Promotion of Science, the German Foundation, and the European Union.

Source: scitechdaily.com