Table of Contents
Overview
Definition of Dark Energy
Dark energy is a hypothetical form of energy that is believed to be responsible for the accelerated expansion of the universe, making up approximately 68-70% of its total energy content.[3.1] This mysterious force acts to push space apart at an increasing rate, fundamentally altering our understanding of cosmic dynamics.[4.1] The term "dark energy" was first introduced in the late 1990s as scientists sought to explain observations that indicated not only an expanding universe but one that is accelerating in its expansion.[13.1] The discovery of dark energy emerged from studies of distant Type Ia supernovae, which revealed that the universe's expansion is not slowing down, as previously thought, but rather speeding up.[13.1] This phenomenon suggests that dark energy has become the dominant component of the universe's energy budget in recent cosmic history, particularly over the last five billion years.[16.1] Despite its significant contribution to the universe's overall energy density, dark energy's actual nature remains elusive, leading to various theories and models attempting to explain its properties and effects.[5.1]History
Key Milestones in Dark Energy Research
The discovery of dark energy in 1998 was a groundbreaking event in cosmology, fundamentally changing the understanding of the universe's expansion. This discovery was made by two international teams, which included American astronomers Adam Riess and Saul Perlmutter, as well as Australian astronomer Brian Schmidt.[46.1] Prior to this discovery, the prevailing belief was that the universe's expansion, initiated by the Big Bang, would gradually slow down due to gravitational forces.[48.1] However, observations of supernova 1997ff, located approximately 10 billion light-years away, provided compelling evidence that the expansion of the universe is actually accelerating.[51.1] This acceleration indicates that dark energy became dominant in the universe several billion years ago, preventing the formation of more galaxies and clusters of galaxies.[46.1] The term "dark energy" was first introduced in a paper by Dragan Huterer and Michael Turner in August 1998, which discussed the prospects of probing dark energy through supernova distance measurements.[49.1] This concept posits that dark energy constitutes approximately 68% of the total energy content of the universe, significantly influencing its large-scale structure and expansion dynamics.[53.1] For nearly three decades following its discovery, dark energy was assumed to be a constant force driving the accelerated expansion of the universe. However, recent advancements, particularly from the Dark Energy Spectroscopic Instrument (DESI), have suggested that dark energy may not be constant over time. DESI's analysis, which spans nearly 15 million galaxies and quasars, indicates that the influence of dark energy might be weakening, challenging the standard cosmological model.[57.1] The implications of these findings are profound, as they suggest that the universe's fate could be different than previously thought. If dark energy's effects diminish, the universe might eventually stop expanding and could even collapse in a scenario known as the "Big Crunch".[47.1] Thus, the ongoing research into dark energy continues to reshape our understanding of cosmic evolution and the ultimate fate of the universe.Recent Advancements
Findings from the Dark Energy Spectroscopic Instrument (DESI)
Recent analyses from the Dark Energy Spectroscopic Instrument (DESI) collaboration have provided compelling evidence suggesting that dark energy, traditionally viewed as a constant force, may actually be evolving over time. This conclusion is drawn from a comprehensive study of data collected over three years, which encompasses nearly 15 million galaxies and quasars, and represents the largest 3D map of the universe ever created. The findings indicate that the influence of dark energy might be weakening, prompting a potential reevaluation of the standard cosmological model.[102.1] The initial results from DESI were presented at an American Physical Society meeting in April 2024, where Dr. Mustapha Ishak-Boushaki highlighted early indications that dark energy could be more dynamic than previously assumed.[88.1] This evolving nature of dark energy is supported by a detailed analysis of the data, which aligns with the standard model of gravity while simultaneously suggesting modifications to our understanding of the universe's accelerated expansion.[101.1] Researchers involved in the DESI project, including notable physicists such as Hee-Jong Seo and her students, have contributed significantly to this research, which tracks dark energy's effects over the past 11 billion years.[90.1] The implications of these findings are profound; if dark energy does indeed fluctuate, it raises the possibility that the universe could eventually halt its expansion and undergo a "Big Crunch," a scenario that contrasts sharply with the prevailing view of perpetual expansion.[91.1]Implications of Evolving Dark Energy
Recent observations have significantly reshaped the understanding of dark energy, particularly its potential evolution over time. For nearly three decades, astronomers believed that dark energy, which drives the universe's accelerated expansion, remained constant. However, new data from the Dark Energy Spectroscopic Instrument (DESI) challenges this assumption, suggesting that dark energy might fluctuate, thereby questioning the standard Lambda CDM model of cosmology.[99.1] Compelling evidence from recent studies indicates that dark energy has weakened over the past 4.5 billion years, contradicting the notion of its constancy.[95.1] This evolving nature implies that the universe's expansion may not be indefinite, potentially leading to a "Big Crunch" scenario where expansion halts and reverses.[96.1] The DESI collaboration's findings support this perspective, suggesting unexpected changes in dark energy that could significantly impact our understanding of the universe's fate.[97.1] Cosmologist Mustapha Ishak-Boushaki highlights that these developments not only challenge current cosmological models but also suggest a more dynamic future for the universe than previously anticipated.[97.1] The DESI analysis, encompassing data from nearly 15 million galaxies and quasars, provides strong evidence that dark energy may not act as a cosmological constant.[108.1] This evolving understanding aligns with discussions on modifying general relativity to explain the universe's accelerated expansion, addressing theoretical consistency and local gravity tests.[92.1] Various dark energy models, such as those by Sharif and Azeem in f(T) gravity, suggest that cosmic inflation and current cosmic acceleration can be explained through modified theories like f(R) gravity.[93.1] As researchers delve deeper into these implications, the role of dark energy in cosmic evolution remains a critical area of investigation.Theoretical Frameworks
Cosmological Constant and Vacuum Energy
The cosmological constant, often associated with vacuum energy, is a fundamental concept in the theoretical frameworks of dark energy. According to the lambda-CDM model of cosmology, dark energy constitutes approximately 68% of the total energy density of the observable universe, with dark matter and ordinary matter contributing 26% and 5%, respectively.[128.1] This model posits that dark energy has a very low density, estimated at about 7×10−30 g/cm³, which is significantly less than the densities of ordinary and dark matter found within galaxies.[128.1] The discovery of dark energy in 1998, through observations of distant supernovae, revealed that the universe is not only expanding but doing so at an accelerating rate, a phenomenon attributed to dark energy.[131.1] This acceleration challenges previous assumptions about cosmic expansion, leading to new insights into the nature of dark energy and its role in cosmic evolution.[132.1] Recent studies, including those from the Dark Energy Spectroscopic Instrument (DESI), suggest that dark energy may not be constant over time, indicating that its influence on the universe's expansion could be changing.[134.1] Furthermore, weak gravitational lensing has emerged as a crucial observational tool for understanding dark energy. This phenomenon allows astronomers to map the distribution of dark matter and measure the effects of dark energy on the structure of the universe by analyzing the distortions in the shapes of distant galaxies.[138.1] The insights gained from weak lensing studies are vital for distinguishing between various dark energy models and understanding their implications for cosmic expansion.[138.1]Alternative Theories and Models
Quintessence is a dynamic scalar field characterized by an equation of state where the ratio of pressure to density, denoted as ( w_q ), varies over time, typically within the range of [-1, 1].[142.1] This contrasts with the cosmological constant, which is static and does not change over time.[142.1] The concept of quintessence emerged from efforts to explain the smallness of the cosmological constant or dark energy in relation to the universe's extensive age, suggesting that dark energy could have been comparable to radiation or dark matter during significant epochs of cosmological history.[141.1] The implications of these alternative theories for the fate of the universe are profound. If dark energy is indeed dynamic, it opens up various scenarios for the universe's future, including the potential for a 'Big Rip,' where the accelerated expansion could eventually tear apart galaxies and even atoms, or a 'Big Crunch,' where gravitational forces might lead to a collapse of the universe.[144.1] Recent research indicates that dark energy, which constitutes nearly 70% of the universe, may be weakening, prompting a reevaluation of its role in cosmology and the ultimate fate of the universe.[145.1] Mathematical models are essential for understanding dark energy and its implications for the evolution of the universe. The simplest model, known as the Lambda Cold Dark Matter (ΛCDM) model, suggests that dark energy remains constant over time, as described by Einstein's equations.[162.1] However, more complex models indicate that dark energy may evolve, which could significantly influence predictions about the universe's future behavior.[162.1] For instance, if the equation of state parameter ( w ) exceeds -1 and the density of dark energy diminishes, gravitational forces could eventually dominate, potentially leading to a recollapse of the universe, commonly referred to as the "Big Crunch".[164.1] Modern cosmological surveys, such as those conducted by SDSS and Planck, provide detailed measurements of the matter distribution across the universe, which help constrain these models and may determine their fate in future studies.[164.1] Modern cosmological models, particularly the lambda-CDM model, posit that dark energy constitutes approximately 68% of the total energy in the observable universe, while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively.[163.1] The density of dark energy is notably low, measured at about 7×10−30 g/cm³, which is significantly less than that of ordinary matter or dark matter found within galaxies.[163.1] Recent astronomical observations suggest that dark energy may be weakening, which raises important questions regarding the ultimate fate of the universe.[165.1] These observations do not directly measure dark energy or its evolution; however, they provide valuable insights into the universe's structure and energy content, aiding in the testing of dark energy models when combined with other data.[165.1] As new results from surveys like DESI are integrated with existing cosmological data, hints emerge that dark energy may be more complex than previously understood, potentially leading to scenarios such as a "Big Rip," where the increasing expansion rate could ultimately tear apart galaxies, stars, and even atoms.[165.1]Observational Evidence
Supernovae and Cosmic Expansion
The discovery of supernovae, particularly supernova 1997ff, has significantly contributed to our understanding of dark energy and its influence on cosmic expansion. Located approximately 10 billion light-years away, supernova 1997ff was pivotal in demonstrating that dark energy became dominant several billion years ago, leading to an accelerated expansion of the universe.[178.1] This supernova, observed using the Hubble Space Telescope, appeared brighter than expected, which challenged existing models of cosmic expansion and provided strong evidence for the existence of dark energy.[183.1] Observations of supernovae have led astronomers to believe that the universe is expanding at an accelerating rate, a phenomenon attributed to dark energy, which is thought to make up about 70% of the universe.[177.1] Recent findings from the Dark Energy Spectroscopic Instrument (DESI) suggest that this acceleration may not be constant over time, indicating that the rate of cosmic expansion could fluctuate.[177.1] The analysis of supernovae, including the farthest ever detected supernova, supports the notion of an accelerating expansion, further reinforcing the case for dark energy's existence.[183.1] The DESI survey, which has created the largest 3D map of the universe by observing 15 million galaxies and quasars, has provided significant evidence regarding dark energy's influence on cosmic evolution over the past 11 billion years.[188.1] This evolving understanding of dark energy is crucial for refining cosmological models and addressing the complexities of the universe's expansion history. Baryon acoustic oscillations (BAO) serve as a powerful tool for measuring the expansion history of the universe, utilizing a characteristic scale imprinted on matter clustering by pressure waves that propagated in the coupled baryon-photon fluid of the pre-recombination universe.[192.1] These oscillations are represented by a series of peaks and troughs with a wavelength of approximately 0.06hMpc−1, and current measurement techniques indicate that BAO exhibit the lowest level of systematic uncertainty among cosmic expansion measurements.[193.1] The existence of dark energy is supported by various observations, including supernovae, the cosmic microwave background (CMB), and BAO, which collectively enhance our understanding of its role in the evolution of the cosmos.[168.1]Gravitational Lensing and Large-Scale Structures
Gravitational lensing and large-scale structures play a crucial role in understanding dark energy and its influence on the universe's expansion. Gravitational lensing occurs when massive objects, such as galaxies or galaxy clusters, bend the light from more distant objects, allowing astronomers to study the distribution of dark matter and the geometry of the universe. This phenomenon provides insights into the large-scale structure (LSS) of the universe, which refers to the patterns of galaxies and matter on scales much larger than individual galaxies or groupings of galaxies.[174.1] The Dark Energy Spectroscopic Instrument (DESI) collaboration has significantly contributed to this field by creating the largest 3D map of the universe, which encompasses nearly 15 million galaxies and quasars. This extensive dataset allows researchers to track dark energy's influence over the past 11 billion years, revealing that the impact of dark energy may be weakening over time.[172.1] The analysis of galaxy clustering, which involves measuring the 3D distribution of galaxies through their angular positions and redshifts, enables direct measurements of cosmic expansion history and the growth of large-scale structures.[184.1] The Dark Energy Spectroscopic Instrument (DESI) has significantly advanced our understanding of dark energy by analyzing data from 15 million galaxies. This data alone could support either an evolving dark energy model or the standard Lambda-CDM model, which posits a cosmological constant.[173.1] However, when researchers integrated this data with preexisting observations, including the locations of thousands of supernovae and insights from the cosmic microwave background (CMB), the results diverged sharply from the Lambda-CDM model. This combination of datasets indicated a clear evolution in dark energy, enhancing our comprehension of its role in cosmic expansion.[173.1] Furthermore, observational techniques such as Type Ia supernova observations and CMB studies have been pivotal in measuring cosmic distances and understanding the universe's expansion history. These methods provide direct evidence of the universe's acceleration, which is crucial for informing dark energy models and elucidating the influence of dark energy on large-scale structures.[185.1] Large-scale structure surveys are pivotal in testing dark energy models, as they map the distribution of galaxies and cosmic structures across vast regions of space. These surveys are essential for probing cosmic acceleration and distinguishing between competing dark energy models, thereby unraveling the mysteries of the universe's accelerated expansion.[187.1] Overall, gravitational lensing and the study of large-scale structures are integral to advancing our knowledge of dark energy and its role in the cosmos.In this section:
Future Directions
Upcoming Research Initiatives
Upcoming research initiatives in the study of dark energy are poised to significantly enhance our understanding of this enigmatic force, which constitutes nearly 70% of the universe and is believed to drive its accelerated expansion.[206.1] The Dark Energy Spectroscopic Instrument (DESI) has emerged as a pivotal tool in this endeavor, utilizing advanced observational techniques to reconstruct the evolution of the equation-of-state parameter of dark energy over time. This research employs the Gaussian process method and compares findings with various modified gravity models, indicating a promising direction for future studies.[202.1] Moreover, recent findings suggest that dark energy may be weakening, raising critical questions about the ultimate fate of the universe. If this trend continues, it could lead to scenarios such as the "Big Rip," where the universe's expansion accelerates to the point of tearing apart galaxies, stars, and even atoms.[205.1] While the current data from DESI is not yet conclusive, it has sparked renewed interest and excitement in the scientific community regarding the fundamental nature of dark energy and its implications for cosmology.[204.1] The upcoming Nancy Grace Roman mission is designed to study dark energy in ways that complement the findings from the Euclid spacecraft, which has already been launched and is gathering data.[224.1] Mission planners intend to utilize insights from Euclid to inform the Roman mission's approach to dark energy research. Recent studies suggest that cosmic dark energy may be weakening, raising significant questions about the ultimate fate of the universe.[205.1] While current observational techniques do not directly measure dark energy or its evolution, they provide valuable clues about the universe's structure and energy content, which can help test dark energy models when combined with other data.[205.1] Furthermore, if dark energy continues to weaken, it could lead to a scenario where the universe eventually collapses over billions of years.[207.1] As researchers continue to explore these complex dynamics, the potential for groundbreaking discoveries regarding dark energy and its implications for cosmic evolution remains substantial.Potential Impacts on Cosmology and Physics
The ongoing research into dark energy is revealing significant implications for our understanding of cosmology and physics. Recent analyses from the Dark Energy Spectroscopic Instrument (DESI) indicate a growing preference for dynamical dark energy over the traditional cosmological constant, suggesting that the standard model of cosmology may require an update.[210.1] This conclusion is supported by data collected over three years, which encompasses nearly 15 million galaxies and quasars, and utilizes the largest 3D map of the universe ever created to track dark energy's influence over the past 11 billion years.[213.1] Furthermore, the evidence for evolving dark energy is now stronger than in previous datasets, indicating that dark energy may be changing in unexpected ways.[214.1] Moreover, studies utilizing baryon acoustic oscillation (BAO) data have reconstructed the evolution of the equation-of-state parameter of dark energy, revealing that it may resemble quintessence and exhibit signs of crossing the phantom barrier.[212.1] Such findings challenge existing theoretical models and suggest that dark energy's impact may have weakened over time, indicating a potential transition in its role within the universe.[217.1] Recent advancements in our understanding of dark energy, particularly through the research conducted by the DESI collaboration, have significant implications for cosmology. The DESI collaboration's latest research supports the standard model of gravity and suggests that dark energy may be evolving over time, based on a detailed analysis of data from millions of galaxies and quasars.[209.1] This evolving understanding of dark energy could influence public perception of science, especially in the context of global challenges such as climate change. The increasing frequency of extreme weather events across the globe, along with intensifying international debates about the political urgency to mitigate climate change and the rise of action-demanding social movements, have contributed to a significant increase in climate change awareness among the population.[208.1] As the public becomes more informed about these scientific developments, it may lead to greater engagement with scientific research and its applications in addressing pressing global issues.In this section:
References
[3] What Is Dark Energy? The Hidden Force Driving the Universe Apart — Dark energy is a mysterious phenomenon that pushes space apart at an accelerating rate, making up 68-70% of the universe. Learn about its history, discovery, and how NASA and ESA telescopes are trying to uncover its secrets.
[4] What is dark energy? One of science's great mysteries, explained - Phys.org — Dark energy is the placeholder name scientists have given to the unknown force causing the universe to expand faster and faster over time.
[5] Dark energy - Wikipedia — Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3 (6×10−10 J/m3 in mass-energy), much less than the density of ordinary matter or dark matter within galaxies. ^ The first appearance of the term "dark energy" is in the article with another cosmologist and Turner's student at the time, Dragan Huterer, "Prospects for Probing the Dark Energy via Supernova Distance Measurements", which was posted to the ArXiv.org e-print archive in August 1998 Archived 22 June 2017 at the Wayback Machine and published in Huterer, D.; Turner, M.
[13] Dark Energy vs. Dark Matter - Key Differences Explained Simply — Dark energy is one of the greatest mysteries of the universe and a key concept in modern cosmology. It is a hypothetical form of energy which was proposed to explain an observation: the universe is not only expanding, but accelerating in its expansion.. Scientists made this discovery in 1998 by studying explosions of distant dying stars called Type Ia supernovae.
[16] Dark Energy Explained By Analogy Metaphor Examples — Dark energy is like the "accelerator," acting to speed up the expansion, and as the dark matter has been diluted dark energy has come to dominate the expension rate for the past 5 billion years, and it will continue to do so in the future." Useful?
[46] Dark energy | Definition, Discoverers, & Facts | Britannica — Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos Dark energy was discovered in 1998 with this method by two international teams that included American astronomers Adam Riess (the author of this article) and Saul Perlmutter and Australian astronomer Brian Schmidt. Studying the effect of dark energy on large-scale structure involves measuring subtle distortions in the shapes of galaxies arising from the bending of space by intervening matter, a phenomenon known as “weak lensing.” At some point in the last few billion years, dark energy became dominant in the universe and thus prevented more galaxies and clusters of galaxies from forming.
[47] Dark energy findings could rewrite our understanding of the universe ... — Dark energy findings could rewrite our understanding of the universe and its fate: "Cusp of a major discovery" - CBS News This image provided by NSF's NOIRLab shows the trails of stars above Kitt Peak National Observatory, where a telescope is mapping the universe to study a mysterious force called dark energy. If dark energy ebbs with time, which now seems plausible, the universe could one day stop expanding and then eventually collapse on itself in what's called the "Big Crunch." It might not seem like the cheeriest fate, but it offers some closure, said cosmologist and study collaborator Mustapha Ishak-Boushaki of the University of Texas at Dallas.
[48] Dark Energy experiment shakes Einstein's theory of Universe - BBC — The discovery of Dark Energy in 1998 was in itself shocking. Up until then the view had been that after the Big Bang, which created the Universe, its expansion would slow down under the force of
[49] Dark energy - Wikipedia — Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3 (6×10−10 J/m3 in mass-energy), much less than the density of ordinary matter or dark matter within galaxies. ^ The first appearance of the term "dark energy" is in the article with another cosmologist and Turner's student at the time, Dragan Huterer, "Prospects for Probing the Dark Energy via Supernova Distance Measurements", which was posted to the ArXiv.org e-print archive in August 1998 Archived 22 June 2017 at the Wayback Machine and published in Huterer, D.; Turner, M.
[51] Dark Energy - HubbleSite — However, only Hubble had the resolution to extend these observations to very distant galaxies. The discovery of supernova 1997ff, located about 10 billion light-years away, provided evidence for dark energy. About halfway into the universe's history — several billion years ago — dark energy became dominant and the expansion accelerated.
[53] Dark Energy - (College Physics I - Introduction) - Fiveable — Dark energy is a mysterious and pervasive form of energy that is believed to be the dominant component of the universe, accounting for approximately 68% of its total energy content. ... Explain how dark energy relates to the cosmological constant and the expansion of the universe. ... The cosmological constant is a term in Einstein's field
[57] New DESI results strengthen hints that dark energy may evolve — Researchers see hints that dark energy, widely thought to be a "cosmological constant," might be evolving over time in unexpected ways. New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration, one of the most extensive surveys of the cosmos ever conducted, reveal that the impact of dark energy may be weakening over time — and the standard model of how the universe
[88] A Hidden Shift in Dark Energy Could Rewrite the Laws of Physics — A new analysis of three years’ worth of data from the Dark Energy Spectroscopic Instrument (DESI) provides even stronger evidence that dark energy, long assumed to be a fixed “cosmological constant,” might actually be evolving over time in unexpected ways. In April 2024, at a meeting of the American Physical Society, Ishak-Boushaki presented the first-year analysis of DESI’s data, which offered early hints that dark energy may not be as constant as once believed. Dr. Mustapha Ishak-Boushaki is a professor of physics at The University of Texas at Dallas and is co-chair of the Dark Energy Spectroscopic Instrument (DESI) collaboration’s working group that interprets cosmological survey data gathered by the international collaboration, which includes more than 900 researchers from over 70 institutions around the world.
[90] The universe might be changing: New DESI data shows dark energy may ... — The universe might be changing: New DESI data shows dark energy may evolve over time New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration use the largest 3D map of our universe ever made to track dark energy’s influence over the past 11 billion years. These DESI researchers include Ohio University Professor of Physics Hee-Jong Seo, as well as several of her students such as Jaide Swanson, a third-year graduate student, who contributed to the first DESI BAO paper last year, Alberto Rosado-Marin, a fifth-year graduate student researching cosmic inflation using data from the DESI survey, and Alexandra Well, a senior Honors Tutorial College student working on the DESI survey in collaboration with scientists across the country.
[91] Dark energy findings could rewrite our understanding of the universe ... — Dark energy findings could rewrite our understanding of the universe and its fate: "Cusp of a major discovery" - CBS News This image provided by NSF's NOIRLab shows the trails of stars above Kitt Peak National Observatory, where a telescope is mapping the universe to study a mysterious force called dark energy. If dark energy ebbs with time, which now seems plausible, the universe could one day stop expanding and then eventually collapse on itself in what's called the "Big Crunch." It might not seem like the cheeriest fate, but it offers some closure, said cosmologist and study collaborator Mustapha Ishak-Boushaki of the University of Texas at Dallas.
[92] Cosmic acceleration and the challenge of modifying gravity — I briefly discuss the challenges presented by attempting to modify general relativity to obtain an explanation for the observed accelerated expansion of the universe. Foremost among these are the questions of theoretical consistency - the avoidance of ghosts in particular - and the constraints imposed by precision local tests of gravity within the solar system. For those models that clear
[93] PDF — DE models was discussed by Sharif and Azeem in f(T) gravity. Both cosmic inflation and an explanation of DE including the present cosmic acceleration is produced by f(R) modified theory. The anisotropic cosmological models in f(R,T) gravity with variable deceleration parameters has been studied upon by Sahoo et al recently.
[95] Evidence mounts that universe's dark energy is changing over time — NASA/ESA/CSA James Webb Space Telescope/Handout via REUTERS/File Photo Purchase Licensing Rights, opens new tab WASHINGTON, March 19 (Reuters) - New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant, as long hypothesized. Sciencecategory · March 19, 2025New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant, as long hypothesized. About Reuters, opens new tab Reuters Diversity Report, opens new tab
[96] Dark energy findings could rewrite our understanding of the universe ... — Dark energy findings could rewrite our understanding of the universe and its fate: "Cusp of a major discovery" - CBS News This image provided by NSF's NOIRLab shows the trails of stars above Kitt Peak National Observatory, where a telescope is mapping the universe to study a mysterious force called dark energy. If dark energy ebbs with time, which now seems plausible, the universe could one day stop expanding and then eventually collapse on itself in what's called the "Big Crunch." It might not seem like the cheeriest fate, but it offers some closure, said cosmologist and study collaborator Mustapha Ishak-Boushaki of the University of Texas at Dallas.
[97] Evidence Mounts for Evolving Dark Energy, DESI Results Find — Evidence Mounts for Evolving Dark Energy, DESI Results Find - News Center | The University of Texas at Dallas A new analysis of data collected over three years by the Dark Energy Spectroscopic Instrument (DESI) collaboration provides even stronger evidence than the group’s previous datasets that dark energy, long thought to be a “cosmological constant,” might be evolving over time in unexpected ways. Dr. Mustapha Ishak-Boushaki, professor of physics in the School of Natural Sciences and Mathematics at The University of Texas at Dallas, is co-chair of the DESI working group that interprets cosmological survey data gathered by the international collaboration, which includes more than 900 researchers from over 70 institutions around the world.
[99] Frozen Cosmic Sound Bubbles Suggest Dark Energy Is Shockingly ... — For almost three decades, astronomers have believed that the universe is expanding faster and faster and that the acceleration of this growth is constant over time—driven by a mysterious force they call “dark energy.” Last April a survey by the Dark Energy Spectroscopic Instrument (DESI) published hints that dark energy may not be as constant as they’d assumed, adding to a pile of concerns that are already threatening the standard model of cosmology. After nearly tripling the researchers’ collection of galaxy coordinates, the new DESI analysis provides the strongest evidence yet that the rate of cosmic expansion fluctuates—finally shedding some light on dark energy, which scientists think constitutes about 70 percent of everything in the universe.
[101] Evidence Mounts for Evolving Dark Energy, DESI Results Find — Evidence Mounts for Evolving Dark Energy, DESI Results Find - News Center | The University of Texas at Dallas A new analysis of data collected over three years by the Dark Energy Spectroscopic Instrument (DESI) collaboration provides even stronger evidence than the group’s previous datasets that dark energy, long thought to be a “cosmological constant,” might be evolving over time in unexpected ways. Dr. Mustapha Ishak-Boushaki, professor of physics in the School of Natural Sciences and Mathematics at The University of Texas at Dallas, is co-chair of the DESI working group that interprets cosmological survey data gathered by the international collaboration, which includes more than 900 researchers from over 70 institutions around the world.
[102] New DESI results strengthen hints that dark energy may evolve — Combining the DESI data with other experiments shows signs that the impact of dark energy may be weakening over time — and the standard model of how the universe works may need an update. The DESI collaboration published a new analysis of dark energy using their first three years of collected data, which spans nearly 15 million galaxies and quasars. New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration use the largest 3D map of our universe ever made to track dark energy’s influence over the past 11 billion years. “It’s not just that the data continue to show a preference for evolving dark energy, but that the evidence is stronger now than it was,” said Seshadri Nadathur, professor at the University of Portsmouth and co-chair of DESI’s Galaxy and Quasar Clustering working group.
[108] New DESI Results Strengthen Hints That Dark Energy May Evolve — New DESI Results Strengthen Hints That Dark Energy May Evolve – Berkeley Lab News Center The DESI collaboration published a new analysis of dark energy using their first three years of collected data, which spans nearly 15 million galaxies and quasars. Taken alone, DESI’s data are consistent with our standard model of the universe: Lambda CDM (where CDM is cold dark matter and Lambda represents the simplest case of dark energy, where it acts as a cosmological constant). “It’s not just that the data continue to show a preference for evolving dark energy, but that the evidence is stronger now than it was,” said Seshadri Nadathur, professor at the University of Portsmouth and co-chair of DESI’s Galaxy and Quasar Clustering working group.
[128] Dark energy - Wikipedia — Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3 (6×10−10 J/m3 in mass-energy), much less than the density of ordinary matter or dark matter within galaxies. ^ The first appearance of the term "dark energy" is in the article with another cosmologist and Turner's student at the time, Dragan Huterer, "Prospects for Probing the Dark Energy via Supernova Distance Measurements", which was posted to the ArXiv.org e-print archive in August 1998 Archived 22 June 2017 at the Wayback Machine and published in Huterer, D.; Turner, M.
[131] Dark energy | Definition, Discoverers, & Facts | Britannica — Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos Dark energy was discovered in 1998 with this method by two international teams that included American astronomers Adam Riess (the author of this article) and Saul Perlmutter and Australian astronomer Brian Schmidt. Studying the effect of dark energy on large-scale structure involves measuring subtle distortions in the shapes of galaxies arising from the bending of space by intervening matter, a phenomenon known as “weak lensing.” At some point in the last few billion years, dark energy became dominant in the universe and thus prevented more galaxies and clusters of galaxies from forming.
[132] Cosmological implications and ghost dark energy model in f (Q,C ... — This work provides new insights into the relationship between dark energy models and modified gravity theory, enhancing our understanding of cosmic evolution. Our findings align with the with the existing observational data (Ade et al., 2016), demonstrating that f (Q, C) model accurately describes the dark energy and cosmic evolution.
[134] Evidence mounts that universe's dark energy is changing over time — NASA/ESA/CSA James Webb Space Telescope/Handout via REUTERS/File Photo Purchase Licensing Rights, opens new tab WASHINGTON, March 19 (Reuters) - New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant, as long hypothesized. Sciencecategory · March 19, 2025New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant, as long hypothesized. About Reuters, opens new tab Reuters Diversity Report, opens new tab
[138] PDF — Abstract Weak gravitational lensing is rapidly becoming one of the principal probes of dark matter and dark energy in the universe. In this brief review we outline how weak lensing helps determine the structure of dark matter halos, measure the expan-sion rate of the universe, and distinguish between modified gravity and dark energy explanations for the acceleration of the universe. We also
[141] Quintessence and the cosmological constant - ScienceDirect — The idea of quintessence originates from an attempt to understand the smallness of the "cosmological constant" or dark energy in terms of the large age of the universe . As a characteristic consequence, the amount of dark energy may be of the same order of magnitude as radiation or dark matter during a long period of the cosmological history
[142] Quintessence (physics) - Wikipedia — Quintessence (Q) is a scalar field with an equation of state where w q, the ratio of pressure p q and density q, is given by the potential energy () and a kinetic term: = = ˙ ˙ + Hence, quintessence is dynamic, and generally has a density and w q parameter that varies with time. Specifically, w q parameter can vary within the range [-1,1]. By contrast, a cosmological constant is static, with
[144] The Mystery of Dark Energy and Its Impact on the Universe — These alternative theories have profound implications for the fate of the universe. If dark energy can indeed change, we could face scenarios that range from the 'Big Rip,' where galaxies and even atoms are torn apart by an ever-accelerating expansion, to the 'Big Crunch,' where the universe could eventually collapse back in on itself.
[145] About Dark Energy and Its Implications | IASPOINT — Dark energy is a mysterious force constituting nearly 70% of the universe. Recent research suggests it may be weakening. This discovery could reshape our understanding of the universe's fate. Scientists are closely examining how this force behaves, with implications for cosmology.
[162] Dark energy may evolve over time, suggests largest 3D map of ... - UCL — UCL Mathematical & Physical Sciences; Dark energy may evolve over time, suggests largest 3D map of universe ... The simplest model suggests that dark energy is constant over time, described by Einstein's equations in the Lambda Cold Dark Matter model. ... in which UCL has also played a key role, we can build a history of how dark energy seems
[163] Dark energy - Wikipedia — Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3 (6×10−10 J/m3 in mass-energy), much less than the density of ordinary matter or dark matter within galaxies. ^ The first appearance of the term "dark energy" is in the article with another cosmologist and Turner's student at the time, Dragan Huterer, "Prospects for Probing the Dark Energy via Supernova Distance Measurements", which was posted to the ArXiv.org e-print archive in August 1998 Archived 22 June 2017 at the Wayback Machine and published in Huterer, D.; Turner, M.
[164] PDF — Exploring The Role Of Dark Energy In The Evolution Of The Large-Scale Structure Of The Universe DOI: 10.9790/0661-2006020613 www.iosrjournals.org 8 | Page Modern cosmological surveys, such as those conducted by SDSS and Planck, provide detailed measurements of the matter distribution across the universe. The Big Crunch (𝑤> −1 with sufficient matter) If 𝑤> −1 and dark energy density diminishes over time, gravitational forces might overcome expansion, causing a recollapse into a "Big Crunch." Exploring The Role Of Dark Energy In The Evolution Of The Large-Scale Structure Of The Universe DOI: 10.9790/0661-2006020613 www.iosrjournals.org 12 | Page Figure 2: Scale Factor 𝑎(𝑡) for Various 𝑤 Values This plot highlights how the universe's expansion rate varies with 𝑤.
[165] Cosmic dark energy may be weakening, astronomers say, raising questions ... — Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe They do not directly measure dark energy or how it evolves, but they provide clues about the universe’s structure and energy content — helping to test dark energy models when combined with other data. When the new DESI results are combined with all this cosmological data, we see hints that dark energy is more complicated than we thought. If dark energy grows stronger over time, the universe could face a “Big Rip” scenario, where galaxies, stars, and even atoms are torn apart by the increasing expansion rate.
[168] 5 - Observational evidence of dark energy - Cambridge University Press ... — The existence of dark energy is supported by a number of observations. This includes (i) the age of the Universe compared to oldest stars, (ii) supernovae observations, (iii) Cosmic Microwave Background (CMB), (iv) baryon acoustic oscillations (BAO), and (v) large-scale structure (LSS).
[172] New DESI results strengthen hints that dark energy may evolve — Combining the DESI data with other experiments shows signs that the impact of dark energy may be weakening over time — and the standard model of how the universe works may need an update. The DESI collaboration published a new analysis of dark energy using their first three years of collected data, which spans nearly 15 million galaxies and quasars. New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration use the largest 3D map of our universe ever made to track dark energy’s influence over the past 11 billion years. “It’s not just that the data continue to show a preference for evolving dark energy, but that the evidence is stronger now than it was,” said Seshadri Nadathur, professor at the University of Portsmouth and co-chair of DESI’s Galaxy and Quasar Clustering working group.
[173] Is Dark Energy Getting Weaker? New Evidence Strengthens the Case. — “We are much more certain than last year that this is definitely a thing,” said Seshadri Nadathur, a member of the Dark Energy Spectroscopic Instrument (DESI) collaboration, the group behind the new result. In isolation, DESI’s 15 million galaxies could match either an evolving dark energy model or the standard theory of cosmology, known as the Lambda-CDM model, which assumes a cosmological constant. (Lambda is the Greek symbol used for Einstein’s cosmological constant, and CDM stands for cold dark matter.) But when DESI researchers also factored in preexisting data on the locations of thousands of supernovas in nearby galaxies, and conditions in the universe’s early days as revealed by remnants of ancient light (called the cosmic microwave background), the combined data sets departed starkly from Lambda-CDM and pointed to an evolution in dark energy.
[174] Large-Scale Structure - Dark Energy Survey — Large-Scale Structure | Dark Energy Survey All Data Y6 Cosmology Data Y3 Cosmology Data DES in the News The Large Scale Structure (LSS) of the universe refers to the patterns of galaxies and matter on scales much larger than individual galaxies or groupings of galaxies. Large Scale Structure also tells us about dark energy. Most theoretical models of dark energy act to slow down this process of gravity creating large structures. Studying the growth of large scale structure across time gives us information about gravity, dark energy, and how each may be changing as the Universe evolves with time. As time goes on (left to right), gravity pulls together matter into large scale patterns. Comments feed
[177] Frozen Cosmic Sound Bubbles Suggest Dark Energy Is Shockingly ... — For almost three decades, astronomers have believed that the universe is expanding faster and faster and that the acceleration of this growth is constant over time—driven by a mysterious force they call “dark energy.” Last April a survey by the Dark Energy Spectroscopic Instrument (DESI) published hints that dark energy may not be as constant as they’d assumed, adding to a pile of concerns that are already threatening the standard model of cosmology. After nearly tripling the researchers’ collection of galaxy coordinates, the new DESI analysis provides the strongest evidence yet that the rate of cosmic expansion fluctuates—finally shedding some light on dark energy, which scientists think constitutes about 70 percent of everything in the universe.
[178] Dark Energy - HubbleSite — However, only Hubble had the resolution to extend these observations to very distant galaxies. The discovery of supernova 1997ff, located about 10 billion light-years away, provided evidence for dark energy. About halfway into the universe's history — several billion years ago — dark energy became dominant and the expansion accelerated.
[183] Blast from the Past: Farthest Supernova Ever Seen Sheds Light on Dark ... — Based on his team's analysis, the supernova, residing 10 billion light-years from Earth, is the farthest ever detected. The team's measurements of this cosmic explosion support mounting evidence that the universe's expansion rate is accelerating, which bolsters the case for the existence of a mysterious form of dark energy pervading the cosmos.
[184] Galaxy Clustering - California Institute of Technology — Galaxy clustering refers to the 3D distribution of galaxies, measured from the angular positions of galaxies in the sky, and the redshifts of the galaxies. Galaxy clustering enables the direct measurement of the cosmic expansion history, H(z), through baryon acoustic oscillations (BAO), and the growth history of cosmic large scale structure, f
[185] PDF — This example categorizes the techniques based on their main objectives, significant instruments or surveys utilized, and their contributions to the field of dark energy studies: Experimental Methodology Core Emphasis Key Tools/Assessments Impact on Dark Energy Research Type Ia Supernova Observations Measuring cosmic distances and expansion rates using standard candles The Supernova Legacy Survey (SNLS), Pantheon, and High-z Supernova Search Provide direct evidence of the acceleration of the universe, which is crucial for comprehending the influence of dark energy on cosmic expansion. Cosmic Microwave Background (CMB) Studying the early universe and cosmological parameters Planck Satellite, WMAP, COBE Provides constraints on the density and expansion history of the universe, www.ijcrt.org © 2024 IJCRT | Volume 12, Issue 11 November 2024 | ISSN: 2320-2882 IJCRT2411827 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt.org h441 informing dark energy models.
[187] PDF — Testing Dark Energy Models with Large-Scale Structure Surveys. This article explores the role of these surveys in testing dark energy models, focusing on their ability to map the distribution of galaxies and cosmic structures across vast regions of space. Probing cosmic acceleration One of the primary goals of large-scale structure surveys is to probe the nature of cosmic acceleration and distinguish between competing dark energy models. Conclusion Large-scale structure surveys represent a powerful tool for testing dark energy models and unraveling the mysteries of the accelerating universe. Testing dark energy models with large-scale structure surveys is a pivotal endeavor in cosmology, enabling us to probe the nature of the universe's accelerated expansion.
[188] Largest 3D map of the universe points to evolving dark energy — Using the Dark Energy Spectroscopic Instrument (DESI) to observe 15 million galaxies and quasars, a team of astronomers has created the largest 3D map of our universe to date and tracked dark energy's influence on the evolution of the cosmos over the past 11 billion years.. Combining their data with other experiments, the researchers uncovered signs that dark energy — the "force
[192] DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and ... — Baryon acoustic oscillations (BAO) provide a powerful tool for measuring the expansion history, using a characteristic scale that is imprinted on matter clustering by pressure waves that propagate in the coupled baryon-photon fluid of the pre-recombination Universe .
[193] PDF — current measurement techniques for the cosmic expansion, Baryon Acoustic Oscillations (BAO) appear to have the lowest level of sys-tematic uncertainty (Albrecht et al. 2006). BAO are a series of peaks and troughs, with a wavelength of approximately 0.06hMpc−1 that are present in the power spec-
[202] Rewriting Cosmic History: DESI's New Map Challenges Traditional Dark ... — Theoretical Implications and Future Directions. Based on the latest DESI observation data, this study reconstructed the evolution of the equation-of-state parameter of dark energy over time by using the Gaussian process method and compared it with some widely studied modified gravity models.
[204] Dark Energy Might Be Changing—And It Could Rewrite Our Understanding of ... — Dark Energy Might Be Changing—And It Could Rewrite Our Understanding of the Universe Dark Energy Might Be Changing—And It Could Rewrite Our Understanding of the Universe DESI is a cutting-edge tool designed specifically to measure the universe’s expansion and probe the elusive dark energy. “It is exciting to think that we may be on the cusp of a major discovery about dark energy and the fundamental nature of our universe.” If dark energy is truly weakening over time, it throws a wrench into the standard cosmological model, the backbone of our understanding of the universe. And while the data isn’t conclusive yet, the possibility that dark energy might be changing over time has sparked a new wave of excitement in the quest to understand the cosmos.
[205] Cosmic dark energy may be weakening, astronomers say, raising questions ... — Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe They do not directly measure dark energy or how it evolves, but they provide clues about the universe’s structure and energy content — helping to test dark energy models when combined with other data. When the new DESI results are combined with all this cosmological data, we see hints that dark energy is more complicated than we thought. If dark energy grows stronger over time, the universe could face a “Big Rip” scenario, where galaxies, stars, and even atoms are torn apart by the increasing expansion rate.
[206] How will the universe end? A changing understanding of dark energy may ... — Scientists are homing in on the nature of a mysterious force called dark energy, and nothing short of the fate of the universe hangs in the balance. The force is enormous—it makes up nearly 70%
[207] Dark energy is weakening and the universe could (eventually ... - NPR — Dark energy is weakening and the universe could (eventually) collapse, study says : NPR Dark energy is weakening and the universe could (eventually) collapse, study says Dark energy is weakening and the universe could (eventually) collapse, study says Dark energy, a mysterious force that scientists believe is behind the accelerated expansion of the universe, is weakening — which could result in the universe over the course of billions of years collapsing on itself, according to new research. Donghui Jeong, professor of astronomy and astrophysics at Penn State University who was not involved in the research, tells NPR while it's too early to determine whether the results from DESI are definitive, it shows good progress is being made in understanding dark energy.
[208] The impact of climate change awareness on behavioral changes in Germany ... — The increasing frequency of extreme weather events across the globe, the intensifying international debates about the political urgency to mitigate climate change, as well as the respective more action demanding social movements have caused a significant increase in climate change awareness among the population. Little research, however, has systematically analyzed the behavioral impact of
[209] Dark Energy May Be Evolving, Transforming Our View of the Universe — The DESI collaboration’s latest research supports the standard model of gravity and hints at evolving dark energy, based on a detailed analysis of data from millions of galaxies and quasars. “For this round of DESI results, I focused my efforts at UT Dallas on conducting a large part of the analysis on gravity, which puts constraints on how matter in the universe moves and how large-scale structures, such as clusters of galaxies, evolve,” said Ishak-Boushaki, an astrophysicist whose research career has focused on questions in cosmology. The new results provide an extended analysis of DESI’s first year of data, which in April contributed to the largest 3D map of the universe to date and revealed hints that dark energy might be evolving over time.
[210] Title: Dynamical dark energy in the light of DESI 2024 data - arXiv.org — The latest findings from the DESI (Dark Energy Spectroscopic Instrument) data release 1 (DR1) , combined with data from the cosmic microwave background and supernovae, suggest a preference for dynamical dark energy over the cosmological constant. This study has considered the Chevallier-Polarski-Linder (CPL) parameterization for the dark energy equation of state (EoS) and has indicated a
[212] Dynamical dark energy in the light of DESI 2024 data - INSPIRE-HEP — In this paper, we introduce an alternative two-parameter parameterization of the dark-energy EoS, at high redshifts, this new parameterization can be approximated to the CPL form. Our findings also indicate that the current value of the EoS of dark energy resembles quintessence, with evidence of a recent crossing of the phantom barrier
[213] New DESI results strengthen hints that dark energy may evolve — Combining the DESI data with other experiments shows signs that the impact of dark energy may be weakening over time — and the standard model of how the universe works may need an update. The DESI collaboration published a new analysis of dark energy using their first three years of collected data, which spans nearly 15 million galaxies and quasars. New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration use the largest 3D map of our universe ever made to track dark energy’s influence over the past 11 billion years. “It’s not just that the data continue to show a preference for evolving dark energy, but that the evidence is stronger now than it was,” said Seshadri Nadathur, professor at the University of Portsmouth and co-chair of DESI’s Galaxy and Quasar Clustering working group.
[214] Evidence Mounts for Evolving Dark Energy, DESI Results Find — Evidence Mounts for Evolving Dark Energy, DESI Results Find - News Center | The University of Texas at Dallas A new analysis of data collected over three years by the Dark Energy Spectroscopic Instrument (DESI) collaboration provides even stronger evidence than the group’s previous datasets that dark energy, long thought to be a “cosmological constant,” might be evolving over time in unexpected ways. Dr. Mustapha Ishak-Boushaki, professor of physics in the School of Natural Sciences and Mathematics at The University of Texas at Dallas, is co-chair of the DESI working group that interprets cosmological survey data gathered by the international collaboration, which includes more than 900 researchers from over 70 institutions around the world.
[217] Evidence mounting that dark energy evolves over time — Percival is co-spokesperson for the Dark Energy Spectroscopic Instrument (DESI) collaboration, which has built the largest 3D map of our universe to date by observing millions of galaxies and quasars. There’s more work to do, but dark energy whose effect was initially stronger than the standard model and then transitioned to be weaker about 4 billion years ago, is a viable candidate for resolving the tensions we’re seeing in the datasets,” says Percival. The DESI cosmological parameters group has done a lot of work testing the robustness of our results, and I'm quite excited to see what the community thinks,” says Alex Krolewski, a postdoctoral researcher at the University of Waterloo.
[224] ESA's Euclid Mission Launches to Explore 'Dark Universe' — The agency's forthcoming Nancy Grace Roman mission will also study dark energy - in ways that are complementary to Euclid. Mission planners will use Euclid's findings to inform Roman's dark energy work. After the Euclid spacecraft separated from the second stage of a SpaceX Falcon 9 rocket, ESA announced a successful launch.