Although our website is about astronomy, we receive many questions that are related, in whole or in part, to the science of physics.
This isn't a surprise, because astronomy and physics are intimately tied together. Physics is the study of the laws that govern the universe, and to the best of our knowledge, those laws are the same here and now as they were long ago and far away.
In order to explain what we see in the night sky, therefore, we appeal to theories originally developed to explain physical phenomena on the Earth. In addition, the extreme environments encountered in astrophysical situations provide a "laboratory" to test these theories under conditions that we could never hope to recreate ourselves.
Physics and Astronomy
Isaac Newton provided one of the first examples of the link between physics and astronomy in the 17th century, when he reasoned that the force of gravity which pulls objects to the Earth is the same force which keeps the Earth and other planets in orbit around the sun.
Later on, in the 19th century, astronomers who were studying stellar spectra (the light from stars split up into its component colors) began to notice that the patterns they saw matched those that occurred when light was shined through different gases in laboratories here on Earth. This discovery allowed astronomers to determine the chemical composition of stellar atmospheres, and in fact, their work later came back to help physicists; the element helium was discovered in spectra from the Sun nearly 30 years before it was found on the Earth.
In recent years, rapid developments in physics and astronomy have kept pace with each other. The twin goliaths of 20th century theoretical physics - general relativity and quantum mechanics - helped explain an enormous number of developments in astronomy, from black holes to cosmology to the various processes by which light is emitted and absorbed in stars, galaxies and the spaces in between. Nuclear physics, meanwhile, predicts and is tested by reactions that take place in the centers of stars, those like the Sun and those undergoing violent events like supernovae.
Despite the above success, there is still much work to be done in physics, especially in the areas that relate to astronomy. General relativity (which deals with massive objects) and quantum mechanics (which deals with small objects) are known to contradict each other, which means we don't currently understand the laws that govern some of the most interesting aspects of our universe - the centers of black holes or the first fraction of a second after the Big Bang.
Physicists continue to seek their holy grail - a unified theory which explains everything in the universe in one fell swoop. One possibile way to reconcile general relativity and quantum mechanics lies in string theory, a theoretical model of the universe still being developed that would involve many more dimensions of space-time than the currently accepted number of four.
Will string theory eventually succeed, or will something else come along to take its place? We don't yet know. But the quest of physicists to understand the universe will continue, and the implications of our increased understanding - on philosophy, religion and society as a whole - will continue to grow.
- Physlink.com: a web reference for all types of Physics, including a section in which you can ask the experts. If you think you are an expert you can even try answering the questions yourself!
- Physics Virtual Bookshelf: Documents on various physics topics written by staff members at the University of Toronto.
- The official String Theory website: everything you ever wanted to know about String Theory.
- Cern Public Site: CERN is the European Centre for Nuclear Research - the world's largest Particle Physics centre.
- What is a singularity? (Beginner)
- Do electrons age? (Beginner)
- How do rockets move in space? (Beginner)
- What would happen if you went back in time and killed your grandmother? (Beginner)
- Do most astronomers believe in God based on the available scientific evidence? (Beginner)
- Why is looking out into space the same as looking back in time? (Beginner)
- Does the Coriolis force determine which way my toilet drains? Does it affect black holes? (Beginner)
- What would happen to us if the sun went out for an hour? (Beginner)
- How can I nominate myself for a Nobel Prize in Physics? (Beginner)
- Is the speed of light constant? (Beginner)
- How can we understand the meaning of large numbers like "a million million?" (Beginner)
- Why is the sky blue and not blue & purple? (Beginner)
- Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
- What is a dimension? (Intermediate)
- How do we feel heat? (Intermediate)
- Is infinite temperature possible? (Intermediate)
- What are black holes made of? (Intermediate)
- How does the Moon stay "suspended" in the air? (Intermediate)
- What causes a particle to decay? (Intermediate)
- What makes a satellite geosyncronise itself with Earth's orbit? (Intermediate)
- Is the gravitational force exerted by the Earth on the Moon equal to the centripetal force acting on the Moon? (Intermediate)
- Are time machines possible? (Intermediate)
- Where does the kinetic energy of infalling bodies come from? (Intermediate)
- How much power is contained in a beam of light? (Intermediate)
- Does evolution contradict the second law of thermodynamics? (Intermediate)
- Can you fire a gun on the Moon? (Intermediate)
- How fast do particles travel in space? (Intermediate)
- Can you use an infinite line of reflectors to send light to the edge of the Universe? (Intermediate)
- Is there such a thing as hyperspace? (Intermediate)
- What is a graviton? (Intermediate)
- Since Earth is spinning, why do we land in the same place when we jump or fall? (Intermediate)
- Could a different theory of gravity explain the dark matter mystery? (Intermediate)
- Does quantum entanglement imply faster than light communication? (Intermediate)
- What happens to a bullet fired on the moon? (Intermediate)
- Is there a project I can do on black holes? (Intermediate)
- How does melting a material reset its radioactive clock? (Intermediate)
- What is the SU(3) quark model? (Intermediate)
- What happens to spacetime inside a black hole? (Intermediate)
- Would the biggest airplanes cause tsunamis if they crashed? (Intermediate)
- What is the photoelectric effect? Why can't multiple low-frequency photons free an electron? (Intermediate)
- How are photons created and destroyed? (Advanced)
- How close do you have to come to the Earth to be influenced by its gravity? (Advanced)
- What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (Advanced)
- Does the temperature of matter increase as it is accelerated to relativistic speeds? (Advanced)
- Has there been an experiment that measured speed faster than the speed of light in vacuum? (Advanced)
- Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them? (Advanced)
How to ask a question:
If you have a question about General Physics which isn't answered above, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.
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Last modified: December 18, 2011 9:42:13 PM
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