Explore & Learn

What Is Dark Matter?

Dark matter is a mysterious type of matter that makes up about 27% of the universe — but we can’t see it, touch it, or shine light on it. It doesn’t give off light or energy, which is why we call it “dark.”

But If We Can’t See It, How Do We Know It’s There?

Because of gravity. Dark matter still has mass, so it pulls on stuff — galaxies, stars, even light.

Here's What It Does:

1. Holds galaxies together

   • Stars in galaxies spin way too fast to be held by just visible matter — dark matter is like a cosmic glue 🌀

2. Bends light (gravitational lensing)

   • It warps space, bending light from faraway galaxies. We can actually see that distortion.

3. Shapes the universe

   • After the Big Bang, dark matter clumped up first — galaxies formed around those invisible clumps.

What Is It Made Of?

We don’t know for sure, but it's probably made of unknown particles like:

• WIMPs (Weakly Interacting Massive Particles)

• Axions

• Sterile neutrinos

• Or even tiny primordial black holes

How Much Stuff Is in the Universe?

Component% of UniverseDark Energy~68%Dark Matter~27%Normal Matter~5%

Yup — everything we can see (stars, planets, people, pizzas) is just that little 5%. The rest is invisible forces and particles running the show 😳

TL;DR:

🌌 WHAT IS A BLACK HOLE?

A black hole is a region in space where gravity is so strong that nothing—not even light—can escape from it. That’s why it looks “black.” They’re like giant space vacuums, but cooler and more dangerous.

💥 HOW ARE BLACK HOLES FORMED?

There are a few types, but here's the main one:

🌟 Stellar Black Holes:

Formed when a massive star (8x our Sun or more) runs out of fuel and collapses under its own gravity after a supernova explosion. Boom. Black hole.

🌀 TYPES OF BLACK HOLES:

1. Stellar Black Holes – formed from dying stars.

2. Supermassive Black Holes – found at the center of galaxies. M87 has one. Our Milky Way has one too: Sagittarius A*.

3. Intermediate Black Holes – not tiny, not huge. Kinda in-between.

4. Primordial Black Holes – hypothetical, formed after the Big Bang. Super tiny.

🧲 WHAT'S INSIDE A BLACK HOLE?

Nobody knows for sure, but here’s what we think:

• The Event Horizon – the “point of no return.” Once you pass this, there’s no escape.

• The Singularity – a tiny point in the center where gravity is infinite, and space and time bend like crazy.

Time literally slows down the closer you get.

⏳ TIME TRAVEL & BLACK HOLES?

YEP. Near a black hole, time slows down massively because of extreme gravity (thanks to Einstein’s General Relativity). It's called gravitational time dilation. In theory, someone orbiting a black hole could experience only a few hours while years pass outside.

🕳️ CAN BLACK HOLES COLLIDE?

YES! When two black holes smash into each other, they create gravitational waves—ripples in space-time. We actually detected these in 2015 (LIGO). Big win for science.

💣 WHAT HAPPENS IF YOU FALL IN?

Depends:

• If it's a small black hole: you get spaghettified—your body stretches like pasta.

• If it's a massive one: you might not even notice crossing the event horizon… for a few seconds at least.

Either way—no coming back. 😬

👁️ CAN WE SEE THEM?

Not directly, but we can see:

• The glowing accretion disk (superheated gas swirling around).

• Gravitational lensing—light bending around it.

• And now, images from the Event Horizon Telescope (M87 and Sagittarius A*).

🔥 WHAT IF A WHITE HOLE SHOWED UP?

White holes are like black holes in reverse. Nothing can enter; everything gets thrown out. They’re hypothetical, but some scientists think the Big Bang might’ve been a white hole.

🧪 FUN FACTS:

• Black holes evaporate slowly over time via Hawking Radiation.

• There might be millions of tiny black holes floating around.

• Some theories say black holes may be gateways to other universes (Wormholes??).

• The Milky Way’s black hole, Sagittarius A*, is 4 million times more massive than the Sun.

A satellite is an object that orbits around a larger object in space, like a planet or a star. There are two main types of satellites:

1. Natural satellites – These are naturally occurring objects, like the Moon, which orbits the Earth.

2. Artificial satellites – These are man-made and are launched into space for different purposes.

Artificial satellites are used for many things, such as:

• Communication (like TV and internet signals)

• Weather forecasting

• GPS and navigation

• Scientific research

• Observing Earth and space

Satellites stay in orbit because of the balance between their speed and the pull of gravity from the planet they’re circling.

💡 What is Power in Physics?

Power is how fast you do work.

🎯 Imagine This:

If two kids both carry the same heavy school bag up the stairs, but one does it faster, that kid used more power.

They did the same work, but faster = more power.

🧮 Easy Formula:

Power=WorkTime\text{Power} = \frac{\text{Work}}{\text{Time}}Power=TimeWork​

So if you do more work in less time, you have more power!

⚡ Units:

• Power is measured in Watts (W)

• 1 Watt = doing 1 unit of work in 1 second

🧒 Real Life Example:

Let’s say:

• You lift your school bag up to a table (that’s work!)

• If you do it in 2 seconds, and your friend does it in 1 second,

• Your friend used more power than you (because they were faster!)👍

🌿 Natural Fabrics (come from plants or animals):

1. Cotton – soft, breathable, great for everyday clothes like t-shirts and jeans.

2. Linen – made from flax, lightweight, perfect for summer, but wrinkles easily.

3. Wool – from sheep; warm, cozy, great for sweaters and coats.

4. Silk – smooth, shiny, luxurious; made by silkworms (fancy dress vibes).

5. Hemp – strong and eco-friendly; getting more popular in sustainable fashion.

🧪 Synthetic Fabrics (man-made in labs/factories):

1. Polyester – durable, wrinkle-resistant, used in lots of clothes.

2. Nylon – stretchy and strong; used in activewear and tights.

3. Acrylic – warm like wool but man-made; often in sweaters.

4. Spandex (Lycra) – super stretchy; found in leggings, swimsuits, sportswear.

5. Rayon – kind of in-between; made from plant stuff but processed chemically.