The size of the universe

 The size of the universe is one of the most mind-blowing concepts in science, and it's still not fully known. Here's what we understand so far:

🌌 Observable Universe

  • The observable universe — the part we can detect light from — has a radius of about 46.5 billion light-years in every direction.

  • That makes the diameter about 93 billion light-years.

  • This might seem odd, since the universe is only about 13.8 billion years old — but because space itself has been expanding, light from very distant galaxies has traveled farther than 13.8 billion light-years.

🔭 Beyond the Observable Universe

  • The entire universe may be much, much bigger — possibly infinite.

  • We can only see as far as light has had time to reach us since the Big Bang.

  • It's like being in a fog: you only see part of the forest, but it might go on forever beyond that.

🌀 Shape and Expansion

  • The universe appears to be flat (not curved like a sphere or saddle), suggesting it's either infinite or so big that the curve is undetectable.

  • It's expanding — galaxies are moving away from each other, and this expansion is accelerating due to a mysterious force called dark energy.

Summary:

FeatureSize/Distance
Age of Universe~13.8 billion years
Observable Universe Radius~46.5 billion light-years
Observable Universe Diameter~93 billion light-years
Entire UniversePossibly infinite

Here are a few visual analogies and comparisons to help you grasp the scale of the universe — especially the observable part:

🌍 Analogy #1: Earth as a Grain of Sand

  • Imagine the Earth is a single grain of sand.

  • Then the observable universe would be like a sphere bigger than the Sun, containing all the galaxies — each galaxy with billions of stars.

  • Our Milky Way alone has about 100–400 billion stars, and there are estimated to be 2 trillion galaxies in the observable universe.

🚗 Analogy #2: Driving Across the Universe

  • Light travels at 300,000 km per second (186,000 miles/sec).

  • Even at that speed, it would take 46.5 billion years to reach the edge of the observable universe.

  • If you tried driving a car at highway speed (100 km/h), it would take you over 13 quadrillion years to cross it.

📸 Analogy #3: Cosmic Horizon

  • Think of standing in the middle of a vast foggy plain. You can only see as far as the fog allows — that’s your observable universe.

  • But the land likely stretches far beyond your line of sight — just as the actual universe may extend infinitely beyond what we can see.

🔭 Visual Representation:

rust
[You]----->|----->|----->|----->| (Each | = 1 billion light-years)

Center: YOU (Earth)
Radius: 46.5 billion light-years
Shape: Sphere
Everything beyond that? Unknown...

🌀 Expansion Twist:

  • The space between galaxies is stretching.

  • Galaxies beyond a certain distance are moving away faster than light — not because they're speeding, but because space itself expands between us.

  • Praise to Allah who created this infinite universe


Comments

Post a Comment

Popular posts from this blog

Ancient silk road

Image
  Ancient silk road The  Silk Road  was and is a network of  trade routes  connecting the  East  and  West , and was central to the economic, cultural, political, and religious interactions between these regions from the 2nd century BCE to the 18th century.The Silk Road primarily refers to the land but also sea routes connecting  East Asia  and  Southeast Asia  with  South Asia ,  Persia , the  Arabian Peninsula ,  East Africa  and  Southern Europe . The Silk Road derives its name from the lucrative trade in  silk  carried out along its length, beginning in the  Han dynasty  in  China  (207 BCE–220 CE). The Han dynasty expanded the  Central Asian  section of the trade routes around 114 BCE through the missions and explorations of the Chinese imperial envoy  Zhang Qian , as well as several military conquests.The Chinese took great interest in the security...
Read more

Khalid ibn al-Walid- Tactics and Strategy

Image
  Khalid ibn al-Walid (592–642), known as the "Sword of Allah," is one of the most celebrated military commanders in history. His tactics and strategies were instrumental in the early Islamic conquests, particularly during the Rashidun Caliphate. Here’s an in-depth look at his military genius: Key Characteristics of Khalid's Tactics and Strategy Adaptability and Flexibility : Khalid was known for his ability to adapt to changing battlefield conditions. He could quickly alter his plans based on the enemy's movements and terrain. Example: During the  Battle of Yarmouk  (636 CE), he shifted forces dynamically to counter Byzantine maneuvers, ensuring victory despite being outnumbered. Speed and Mobility : Khalid emphasized rapid movement to surprise and outmaneuver his enemies. His forces often traveled light and moved quickly across vast distances. Example: His famous  march from Iraq to Syria  in 634 CE, covering over 800 kilometers in just 18 days, allowed him to...
Read more