Gravitational Waves
Gravitational waves are tiny, invisible ripples in space. They travel for huge distances at the speed of light. The waves squeeze and stretch any objects they pass, but only by a tiny amount.
- Evidence for Gravitational Waves
On 14th September 2015, scientists announced they had the first evidence for gravitational waves. This was nearly 100 years after Einstein published his work.
Relativity
Gravity is the force we are most familiar with in everyday life. It has been studied for longer than the other forces of nature. However, it is also the least well understood.
- Law of Universal Gravitation
Newton had correctly explained that every object in the Universe has a force which can be felt by every other object as a ‘pull’. We call it an ‘attractive’ force because it attracts objects towards each other.
The strength of this force is linked to the mass of the object. The more massive the object, the stronger the force. Newton also found that the force is linked to the distance between the objects. The further the distance, the weaker the force.
Gravity
Gravity is the name of the force that pulls objects together. It is a non-contact force. This means it acts on objects that are not touching each other.
- Gravitational Field Strength
All objects with mass have a gravitational field. We measure the gravitational field strength (g) in N/kg. The more mass an object has, the greater its gravitational field strength will be.
On Earth, g = 9.8 N/kg.
- Weight
Weight is the force acting on an object due to gravity. It is measured in Newtons (N). You can calculate weight using this equation.
Weight = Mass x Gravitational Field Strength
Light and Telescopes
One of the first people to study light was Ibn al-Haytham (known as Alhazen). He was a Muslim, living in Egypt in the early 11th Century. Alhazen is first person we know of who used the scientific method. He wanted to know why our eyes could see things.
Hans Lipperhey (also spelt Lippershey) was the first person to write down a design for a telescope. He made spectacles for a living, and in 1608 he applied for a patent for his new tool. He said it was "for seeing things far away as if they were nearby". Hans did not get the patent because other people were making similar tools. But, Hans was paid for his design. The first telescopes, known as Dutch Telescopes, contained both a convex and a concave lens.
Isaac Newton
Occupation
Mathematician, Astronomer, and Physicist
Year born
1643
Research Areas
Optics, maths, motion, gravity
- Early Life
Isaac was born in Woolsthorpe, England. For most of this childhood he was raised by his grandmother and went to a grammar school. At school, he learned Latin, Ancient Greek, and some maths. His mother wanted him to be a farmer, but Isaac hated farming. At the age of 18, Isaac went to the University of Cambridge. His uncle had previously studied there and recommended him to the university.
Distances in Space
Measure the Sun's Rotation
Mario Hamuy
Credit: By Puzhok (own work) at English Wikipedia - GFDL
Original text: I (Puzhok) created this work entirely by myself.
Occupation: Astronomer and Professor
Year born: 1960