A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[summary] => [format] => 2 [safe_value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[safe_summary] => ) ) ) [field_date_box_lancio_news] => Array ( [und] => Array ( [0] => Array ( [value] => 2025-07-22T00:00:00 [timezone] => Europe/Paris [timezone_db] => Europe/Paris [date_type] => date ) ) ) [field_etichetta_box_lancio_news] => Array ( ) [field_img_box_lancio_news] => Array ( [und] => Array ( [0] => Array ( [fid] => 141600 [uid] => 2032 [filename] => download.jpeg [uri] => public://download_7.jpeg [filemime] => image/jpeg [filesize] => 5828 [status] => 1 [timestamp] => 1753180107 [type] => image [field_file_image_alt_text] => Array ( ) [field_file_image_title_text] => Array ( ) [field_folder] => Array ( [und] => Array ( [0] => Array ( [tid] => 2048 ) ) ) [metadata] => Array ( [height] => 162 [width] => 310 ) [height] => 162 [width] => 310 [alt] => Univers [title] => ) ) ) [field_link_alla_news] => Array ( ) [field_link_esterno_news] => Array ( ) [field_pagina_associata] => Array ( ) [field_link_etichetta] => Array ( ) [field_abstract_news] => Array ( [und] => Array ( [0] => Array ( [value] => A team of scientists from the University of Padua, in collaboration with the University of Barcelona and the University of Pisa, has published a paper proposing a new theory about the origin of our Universe [format] => [safe_value] => A team of scientists from the University of Padua, in collaboration with the University of Barcelona and the University of Pisa, has published a paper proposing a new theory about the origin of our Universe ) ) ) [field_allegato_news] => Array ( ) [field_categorie_news] => Array ( [und] => Array ( [0] => Array ( [tid] => 2296 ) ) ) [field_pub_date] => Array ( [und] => Array ( [0] => Array ( [value] => 2025-07-22T00:00:00 [value2] => 2026-07-22T00:00:00 [timezone] => Europe/Paris [timezone_db] => Europe/Paris [date_type] => date ) ) ) [field_layout_news] => Array ( [und] => Array ( [0] => Array ( [value] => single ) ) ) [field_testo_opzionale_news] => Array ( ) [field_url_en_page] => Array ( [und] => Array ( [0] => Array ( [value] => /news/unipd-studia-nuovo-modello-comprendere-origini-universo [format] => [safe_value] => /news/unipd-studia-nuovo-modello-comprendere-origini-universo ) ) ) [field_url_en_page_label] => Array ( [und] => Array ( [0] => Array ( [value] => Italian version [format] => [safe_value] => Italian version ) ) ) [path] => Array ( [pathauto] => 1 ) [name] => francesca.forzan [picture] => 0 [data] => b:0; [num_revisions] => 2 [current_revision_id] => 497541 [is_current] => 1 [is_pending] => [revision_moderation] => [entity_view_prepared] => 1 ) [#items] => Array ( [0] => Array ( [value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[summary] => [format] => 2 [safe_value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
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) ) [field_img_box_lancio_news] => Array ( [#theme] => field [#weight] => 0 [#title] => Immagine [#access] => 1 [#label_display] => above [#view_mode] => teaser [#language] => und [#field_name] => field_img_box_lancio_news [#field_type] => image [#field_translatable] => 0 [#entity_type] => node [#bundle] => box_lancio_news [#object] => stdClass Object ( [vid] => 497541 [uid] => 2032 [title] => Unipd develops new model to understand the origins of the Universe [log] => [status] => 1 [comment] => 0 [promote] => 1 [sticky] => 0 [nid] => 120080 [type] => box_lancio_news [language] => it [created] => 1753180107 [changed] => 1753180148 [tnid] => 0 [translate] => 0 [revision_timestamp] => 1753180148 [revision_uid] => 2032 [body] => Array ( [und] => Array ( [0] => Array ( [value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[summary] => [format] => 2 [safe_value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
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Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[summary] => [format] => 2 [safe_value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
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Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
[summary] => [format] => 2 [safe_value] =>A team of scientists, including Daniele Bertacca and Sabino Matarrese from the Department of Physics and Astronomy "G. Galilei" at the University of Padua, in collaboration with Raúl Jiménez from the University of Barcelona and Angelo Ricciardone from the University of Pisa, has published an article in Physical Review Research Letters titled "Inflation without an inflaton", proposing a new theory about the origin of our Universe. This new theoretical framework represents a radical shift in how we understand the very first moments of the Universe's existence—without relying on some of the speculative elements traditionally assumed in the standard theory of inflation.
For decades, cosmologists have worked within the inflationary paradigm, a model suggesting that the Universe underwent an incredibly rapid expansion, setting the stage for everything we observe today. This paradigm explains why the Universe appears so homogeneous and isotropic, while also accounting for the inhomogeneous structures like galaxies and galaxy clusters.
However, there’s a catch: the theory involves too many “free” or “adjustable” parameters that can be tweaked at will. In science, too much flexibility can be problematic—it becomes difficult to tell whether a model is genuinely making predictions or simply adapting itself to fit the observed data after the fact.
The international research team has proposed a new model in which the early Universe doesn't require any of these arbitrary parameters. Instead, it depends on a single energy scale that determines all observable predictions. The researchers start from a well-established cosmological state known as de Sitter space-time, a geometric model of a Universe dominated by vacuum energy and expanding at an accelerating rate—like a balloon inflating faster and faster at every point.
This new model doesn’t rely on hypothetical fields or particles such as the so-called “inflaton” field. Rather, it suggests that the natural quantum oscillations of space-time itself—in the form of quantum gravitational waves (or “gravitons”)—were enough to trigger the tiny density fluctuations that eventually led to the formation of galaxies, stars, and planets.
These gravitational ripples evolve in a nonlinear way, meaning they interact and build complexity over time, leading to testable predictions. Researchers can now analyze, scrutinize, and compare these predictions with data from Earth-based and space-based experiments.
“Understanding the origin of the Universe is not just a philosophical pursuit—it helps us answer fundamental questions about who we are and where everything comes from,” say the authors of the newly published theory. “This new proposal offers a simple yet powerful framework. It delivers clear predictions that can be confirmed or ruled out by future observations—such as the measurement of the amplitude of primordial gravitational waves and statistical studies of cosmic structure. Moreover, it shows that no speculative ingredients are needed to explain the cosmos, just a deep understanding of gravity and quantum physics. This model could mark a new chapter in how we think about the birth of the Universe.”
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