Apr 22, 2022 07:48 PM
https://astronomy.com/magazine/news/2022...t-universe
INTRO: In less time than it takes to snap your fingers, the universe flashed into existence.
Cosmogenesis is the breathtaking story of how this happened. It includes, in its later moments, the creation of the primordial elements and depicts their organization by dark matter and gravity into vast cosmic structures on the largest scales. Meanwhile, on smaller scales, local gravitational collapse created stars and, later, planets.
The prelude to this story began with a major cosmological event: inflation. Between 10-36 and 10-34 seconds after the Big Bang, the physical scale of our universe doubled in size more than 50 times, so that by today, it is trillions of times larger than the 14 billion-light-year extent we can observe.
Inflation’s effects shaped the cosmos we see today: geometrically flat, homogeneous, and with the right mix of matter and energy. But what happened before inflation? The answer takes us deep into the nature of reality itself, and face to face with a time called the Planck era.
The GUT era
To probe the Planck era, we must first bridge an equally mysterious period called the GUT era.
The period of cosmic history before inflation kicked off, ranging from 10-43 to 10-36 seconds after the Big Bang, is almost unimaginable. But we think its properties are nevertheless calculable. During this time, gravity had become its own distinct force, but those forces we now experience individually as the separate strong, weak, and electromagnetic forces were all essentially indistinguishable.
There are many ways this unification could happen, each advocated as a separate theory. Collectively these are called Grand Unification Theories or GUTs. The simplest GUTs propose the existence of families of supermassive particles of 1014 gigaelectronvolts (GeV) or more. They are partners to our familiar Standard Model particles, which have masses from 0 to about 150 GeV.
The temperature and density of the cosmos during the GUT era was unimaginably gargantuan: 1028 kelvins and 1080 grams per cubic centimeter. (For comparison, a neutron star has a density of about 1015 g/cm3.) Typical distances between particles were 10-26 cm or less. What’s more, particles simply popped in and out of existence in matter-antimatter pairs from out of their respective quantum fields. At this energy scale, where typical particle energies were above 1015 GeV — namely, those of the supermassive GUT particles — the familiar Standard Model particles were essentially massless by comparison. They behaved more like photons.
The comings and goings of the supermassive GUT particles tossed the gravitational field of the universe about like waves on a stormy sea. Space and time themselves were warped by the many sudden changes in this turbulent gravitational field.
The GUT era was indeed an incomprehensible, fluctuating, hot mess of interacting particles and fields. Physicists believe these messy conditions continued all the way down to a scale of 10-33 cm and time intervals of 10-43 seconds, called the Planck size and time. The Planck scale, whether referring to size, time, mass, or otherwise, is the smallest unit of the universe we can describe — or, perhaps, that even exists. Below these scales, our current theories about space and time completely break down. If we try to describe the universe at a time before 10-43 seconds in its history — the Planck era — we discover that both time and space lose their conventional meaning.
The nature of time and space
The reason our descriptions of time and space break down near the Planck era is that the gravitational field at this time was so distorted and turbulent with its own quantum fluctuations, it is impossible to define a clock to measure time or a ruler to measure length. Only a fully quantum mechanical description of gravity — which we don’t yet have — will let us probe deeper into this corner of cosmic history.
If we could examine physics at the Planck scale today, we would see what this quantum chaos is like. But at this scale, nature defeats our best efforts to observe it at all... (MORE - details)
INTRO: In less time than it takes to snap your fingers, the universe flashed into existence.
Cosmogenesis is the breathtaking story of how this happened. It includes, in its later moments, the creation of the primordial elements and depicts their organization by dark matter and gravity into vast cosmic structures on the largest scales. Meanwhile, on smaller scales, local gravitational collapse created stars and, later, planets.
The prelude to this story began with a major cosmological event: inflation. Between 10-36 and 10-34 seconds after the Big Bang, the physical scale of our universe doubled in size more than 50 times, so that by today, it is trillions of times larger than the 14 billion-light-year extent we can observe.
Inflation’s effects shaped the cosmos we see today: geometrically flat, homogeneous, and with the right mix of matter and energy. But what happened before inflation? The answer takes us deep into the nature of reality itself, and face to face with a time called the Planck era.
The GUT era
To probe the Planck era, we must first bridge an equally mysterious period called the GUT era.
The period of cosmic history before inflation kicked off, ranging from 10-43 to 10-36 seconds after the Big Bang, is almost unimaginable. But we think its properties are nevertheless calculable. During this time, gravity had become its own distinct force, but those forces we now experience individually as the separate strong, weak, and electromagnetic forces were all essentially indistinguishable.
There are many ways this unification could happen, each advocated as a separate theory. Collectively these are called Grand Unification Theories or GUTs. The simplest GUTs propose the existence of families of supermassive particles of 1014 gigaelectronvolts (GeV) or more. They are partners to our familiar Standard Model particles, which have masses from 0 to about 150 GeV.
The temperature and density of the cosmos during the GUT era was unimaginably gargantuan: 1028 kelvins and 1080 grams per cubic centimeter. (For comparison, a neutron star has a density of about 1015 g/cm3.) Typical distances between particles were 10-26 cm or less. What’s more, particles simply popped in and out of existence in matter-antimatter pairs from out of their respective quantum fields. At this energy scale, where typical particle energies were above 1015 GeV — namely, those of the supermassive GUT particles — the familiar Standard Model particles were essentially massless by comparison. They behaved more like photons.
The comings and goings of the supermassive GUT particles tossed the gravitational field of the universe about like waves on a stormy sea. Space and time themselves were warped by the many sudden changes in this turbulent gravitational field.
The GUT era was indeed an incomprehensible, fluctuating, hot mess of interacting particles and fields. Physicists believe these messy conditions continued all the way down to a scale of 10-33 cm and time intervals of 10-43 seconds, called the Planck size and time. The Planck scale, whether referring to size, time, mass, or otherwise, is the smallest unit of the universe we can describe — or, perhaps, that even exists. Below these scales, our current theories about space and time completely break down. If we try to describe the universe at a time before 10-43 seconds in its history — the Planck era — we discover that both time and space lose their conventional meaning.
The nature of time and space
The reason our descriptions of time and space break down near the Planck era is that the gravitational field at this time was so distorted and turbulent with its own quantum fluctuations, it is impossible to define a clock to measure time or a ruler to measure length. Only a fully quantum mechanical description of gravity — which we don’t yet have — will let us probe deeper into this corner of cosmic history.
If we could examine physics at the Planck scale today, we would see what this quantum chaos is like. But at this scale, nature defeats our best efforts to observe it at all... (MORE - details)