Scientists Finally Measured the Universe's Actual Size

The Universe's True Size: Mind-Blowing Revelations

Key Concepts:

Observable Universe: The portion of the universe we can see, approximately 93 billion light-years across.
Dark Matter & Dark Energy: Invisible forces dominating the cosmic landscape.
Sephiid Variables: Pulsating stars used as "standard candles" to measure cosmic distances.
Red Shift: Stretching of light wavelengths due to the expansion of the universe.
Cosmic Microwave Background (CMB): Ancient light from the early universe.
Hubble's Law: The relationship between a galaxy's distance and its recession velocity.
Cosmic Horizon: The boundary beyond which we can never see due to the expansion of space.
Parallax: A method for measuring distances to nearby stars based on their apparent shift against distant backgrounds.
Type Ia Supernova: Stellar explosions used as standard candles for measuring vast cosmic distances.
Sloan Great Wall & Hercules Corona Borealis Great Wall: Examples of the largest known cosmic structures.
Cosmic Distance Ladder: A series of measurement techniques used to determine distances to increasingly distant objects.

I. Shattering Cosmic Measurements

Initial Understanding: The universe is 93 billion lightyears across, contains over 2 trillion galaxies, and holds structures spanning 4 billion lightyears.
New Discoveries: The actual universe could be 250 times larger than what we can see. Measurements of the observable universe might be off by millions of lightyears.

II. Henrietta Swan Levit and Sephiid Variables

Levit's Discovery (1908): Sephiid variable stars pulse with a rhythm, and the brighter they are, the slower they pulse.
Significance: This allows astronomers to determine a star's true brightness by timing its flicker. Knowing the true brightness and apparent brightness reveals its distance.
Analogy: Recognizing a friend's voice across a crowded room.
Impact: Proved that spiral nebula were entire galaxies located millions of light years beyond the Milky Way.

III. Expanding the Known Universe

Edwin Hubble (1925): Used Levit's method to prove that the Andromeda galaxy is 2.5 million lightyears from Earth.
Result: The known universe expanded from 100,000 lightyears to over 5 million lightyears in diameter.
Modern Telescopes: Reveal galaxies whose light began traveling toward us when the universe was barely 300 million years old.
Scale: If the Milky Way were the size of a dinner plate, the observable universe would be larger than North America.
Dark Matter and Dark Energy: Everything we can see might represent less than 4% of what actually exists.

IV. The Emptiness of Space

Ancient Beliefs: Ancient Greek astronomers thought the cosmos was a series of crystal spheres rotating around Earth. Aristotle calculated that the entire universe could fit inside a ball roughly the size of our solar system.
Early 1900s: Astronomers believed the Milky Way represented the complete universe, measuring about 30,000 light years across.
Cosmic Spacing: The space between your pillow and your bedroom ceiling contains the same proportion of emptiness that exists between galaxies in the observable universe.
Parallax Breakthrough: Friedrich Bessel (1838) determined that the star 61 Signney lay 11 light years from Earth.
Modern Measurements: The observable universe contains roughly 10 to the power of 82 atoms spread across a sphere 93 billion lightyears in diameter. If you could somehow collect every atom in the observable universe and spread them evenly throughout that volume, each atom would be separated from its nearest neighbor by about 3 ft.

V. James Webb Space Telescope Revelations

Impossible Galaxies: The James Web Space Telescope photographed galaxies that formed before the universe was old enough for such galaxies to exist.
Red Shift Detection: James Web was specifically designed with infrared sensors to detect stretched ancient light.
Early Galaxy Properties: Primordial galaxies appear surprisingly bright, massive, and well organized for such early cosmic times.
Jadez GSZ140: A galaxy containing billions of stars and shows signs of active star formation despite existing when the universe was barely 400 million years old.
Heavy Elements: The James Webb telescope has also detected carbon, oxygen, and other heavy elements in galaxies formed less than 500 million years after the Big Bang.

VI. The Expanding Universe and Hubble's Law

Expanding Balloon Analogy: Measuring the universe is like measuring a balloon while someone continuously inflates it.
Hubble's Law: More distant galaxies recede from us faster than nearby ones. Space expands at roughly 70 km/s for every mega parc of distance (3.3 million lightyears).
Observational Horizon: Galaxies can recede faster than the speed of light, creating an observational horizon beyond which we can never see.
Dark Energy: A mysterious force making up roughly 68% of the universe, causing accelerated expansion.
Distant Galaxy Jesus GSA40: Appears to us as it was just 290 million years after the Big Bang, but cosmic expansion has carried it to a distance of over 33 billion lightyears.

VII. The Cosmic Horizon and Beyond

61 Signney: The first cosmic landmark to prove that the universe has boundaries we can never cross.
Stellar Parallax: Bessel measured the distance to 61 Signney in 1838 using stellar parallax.
Observable Universe: A sphere of observability surrounding Earth with a radius of roughly 46 billion light years in all directions, creating the observable universe with a diameter of 93 billion lightyears.
Cosmic Horizon: An edge as real and impossible as the horizon on Earth's oceans.
Beyond the Observable: Statistical analysis suggests the total universe is at least 250 times larger than the observable portion.
Cosmic Microwave Background: Marks the edge of what we can observe with electromagnetic radiation.
Gravitational Waves: Offer the possibility of observing beyond the cosmic microwave background.

VIII. Recalibrating the Observable Universe

2024 Discovery: Astronomers made a discovery that shrunk the observable universe by over 190 billion billion miles.
New Radius: The observable universe measures 45.34 billion lightyears in radius rather than the previously accepted 45.66 billion lightyears.
Reason: More accurate measurements of how fast the universe has expanded since the Big Bang.
Cosmic Microwave Background: Provides the key evidence for this revised measurement.
Impact: Affects our understanding of cosmic structure formation, dark matter distribution, and the total number of galaxies in existence.

IX. The Largest Cosmic Structures

Sloan Great Wall: Stretches across 1.4 billion lightyears, the largest single structure ever discovered.
Cosmic Web: Galaxies form an intricate network of filaments, walls, and sheets separated by vast empty regions called cosmic voids.
Hercules Corona Borealis Great Wall: Spans over 10 billion lightyears, roughly twice the size of the Sloan Great Wall.
Cosmological Principle: The universe should appear roughly the same in all directions when viewed on sufficiently large scales.
Early Structure Formation: Large scale structures began forming much earlier in cosmic history than previously thought.

X. The Trillion Galaxy Count

Undercounting: Astronomers had undercounted the number of galaxies in the observable universe by a factor of 10.
Revised Count: Over 2 trillion individual galaxy systems.
Reason: Distant galaxies appear much fainter than nearby ones, and many small galaxies that existed in the early universe have since merged together to form larger systems.
James Webb Confirmation: The James Webb Space Telescope has begun detecting some of these previously invisible galaxies.
Implications: More potential sites for planet formation and biological evolution than previously estimated.

XI. Parallax: Measuring the Immeasurable

Parallax Principle: Observing how nearby objects appear to shift position against distant backgrounds when viewed from different locations.
Earth's Orbit: Astronomers use Earth's orbit around the sun to create a massive parallax baseline.
Friedrich Bessel (1838): Observed the star 61 Signney, detecting a parallax angle of just 0.3 arcsec.
Gaia Mission: Has measured parallax distances to over 1 billion stars with incredible precision.
Cosmic Distance Ladder: Parallax forms the first rung of the cosmic distance ladder.
Limitation: Stellar shifts become too small to detect once stars lie more than a few thousand lightyears from Earth.

XII. Standard Candles: Sephiids and Supernovae

Standard Candles: Objects whose intrinsic brightness is known.
Sephiid Variables: Serve as excellent standard candles because their pulsation periods directly relate to their true luminosity.
Type Ia Supernova: Stellar explosions that occur when a white dwarf star reaches the Chandrakar limit (1.4 solar masses).
Type Ia Supernova Brightness: Every type supernova reaches approximately the same peak brightness equivalent to the luminosity of 5 billion suns.
Dark Energy Discovery: Saw Pearl Mutter, Brian Schmidt, and Adam Rius used type supernovi in the 1990s to discover that cosmic expansion is accelerating, driven by dark energy.

XIII. Sephiid Variables as Cosmic Lighthouses

Pulsation Mechanism: Sephiid variable stars expand and contract like beating hearts.
Period-Luminosity Relationship: More massive luminous sephiids pulsate more slowly than smaller dimmer ones.
Henrietta Swan Levit (1912): Discovered this relationship while studying Sephiids in the small melanic cloud.
Hubble Space Telescope: Has observed sephiids in galaxies up to 100 million lightyears away.
James Web Space Telescope: Can observe sephiids at greater distances than ever before.

XIV. The Cosmic Microwave Background and the Expansion Crisis

Cosmic Microwave Background (CMB): Ancient light from the moment roughly 380,000 years after the Big Bang.
CMB Mapping: The Plank satellite mapped these fluctuations with extraordinary precision.

XV. Conclusion

The video details the ongoing quest to measure the universe's size, highlighting the evolution of measurement techniques, the discovery of unexpected phenomena like dark energy, and the challenges posed by the expanding nature of space. From Henrietta Swan Levit's groundbreaking work with Sephiid variables to the James Webb Space Telescope's observations of early galaxies, each discovery has reshaped our understanding of the cosmos and revealed the vastness and complexity of the universe. The video emphasizes that our current measurements are still subject to revision and that the true extent of the universe may remain forever beyond our grasp.