beginnings and endings
1. dark matter: the force that holds stars in the sky. it can be proven in several ways: dark matter neither absorbs or emits light, scientist can observe it by measuring the effects of its gravity. this can be easily seen when two galaxies collide. Scientist use special telescopes to detect the location and amount of mass during the collision. Most of this mass is hot gas, which is the energy emitted during the collision. The other majority of mass is stars. All of this mass is contained in the galaxies. However, the force of dark matter keeps the stars (visible matter) separated. This dark matter is directly related to dark energy (the force that is propelling the universe’s expansion).
2. DARK ENERGY:
how can we know how big the universe is? we observe white dwarfs (the standard for light in the universe) to see how much light they emit. ["Because all white dwarfs achieve the same mass before exploding, they all achieve the same luminosity and can be used by astronomers as "standard candles."" (NASA)] By observing the light we can conclude their distance (using the 1/r2 law). By knowing the distance, we can know how long ago they occurred, by looking at their wave length and intensity of light. When scientists searched for these supernovae they expected that the expansion of the universe would be slowing (stars would be brighter–closer to us) but instead the supernovae was much dimmer, suggesting that they are father away… hence the conclusion of THE UNIVERSE IS GROWING!
3. Cosmic Microwaves (not just for popcorn): cosmic microwave background indicate that the Universe has a flat geometry. Except there is not enough matter in the universe to produce this plain. Dark energy is the “stuff” that must fill the vast reaches of mostly empty space in the universe in order to be able to make space accelerate in its expansion. In this sense, it is a “field” just like an electric field or a magnetic field, both of which are produced by electromagnetic energy.
4. however, there must be something more propelling the universe. if scientist measure the supernovae from the beginning of the universe, then there are other stars beyond those, which our telescopes cannot see. this would lead me to conclude there is a black hole from the first gravitational collapse of a star, when our universe was only a few million of years old. This star would have been massive, larger than any star we know of today (Pistol Star is the largest). It’s mass would result in a huge supernova and BAM the primordial black hole. …
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Some misinterpretations
Sam,
It's always good when someone who finds the universe fascinating decides to blog about it. But as a science writer, I make sure I understand something before trying to explain it. I'm afraid you have a few serious mis-statements or misinterpretations here.
First, the existence of dark matter is still a hypothesis, albeit a well-supported one. Its composition is still unknown, as is its distribution within galaxies, where its existence was first observed. Here's how I describe its discovery in Physics: Decade by Decade (Twentieth-Century Science set, Facts On File, 2007) (Copyright 2007, Alfred B. Bortz, all rights reserved):
Recent observations of colliding galaxies have begun to shed a bit of "light" on the distribution of dark matter, so when you mention galactic collisions, you need to note that it is only a recent small part of the dark matter story.
Second, it is incorrect to say, "This dark matter is directly related to dark energy." Those are independent phenomena.
Your description of how dark energy was discovered by standard candles is correct as far as it goes, but to provide the whole picture, you need to describe the disagreement between the distance measured by applying Hubble's law to the red-shift of galaxies and the distance measured by standard candles in those galaxies. The origin of dark energy and the accelerating expansion of the universe is under intense study, but it could be as simple as the Cosmological Constant in Einstein's General Relativity.
Your description of dark energy as "stuff" filling "mostly empty space" is not accurate. It may be an inherent property of spacetime.
Einstein introduced the Cosmological Constant to allow for a static universe (neither expanding nor contracting), which he thought to be the case. About ten years later, Hubble's work showed that the universe was expanding, and Einstein declared that constant to be his greatest mistake. With dark energy, it could be that Einstein's greatest mistake was calling it a mistake in the first place.
Third, I presume you are referring to the Cosmic Microwave Background (CMB), which is the greatly red-shifted light of the Big Bang, or more precisely light from about 300,000 years after the Big Bang when the universe had cooled to the point that atoms could form and was thus transparent to electromagnetic waves. Calling the CMB a field is incorrect.
Finally, your fourth statement is simply wrong. The Big Bang plus dark energy is sufficient to describe the observed expansion and acceleration of the universe. No additional propulsion is necessary.
I wish I could provide a more favorable critique of your post, but anyone willing to call himself a Science Geek is clearly willing to learn. I have reviewed numerous physics, astronomy, and cosmology books for readers like you in several major metropolitan newspapers, and I have archived my reviews at The Science Shelf.
Three particularly interesting titles relating to your topics here are:
* Alpha and Omega: The Search for the Beginning and the End of the Universe by Charles Seife
* Strange Matters: Undiscovered Ideas at the Frontiers of Space and Time by Tom Siegfried
and
* The Hole in the Universe: How Scientists Peered over the Edge of Emptiness and Found Everything by K. C. Cole
Happy reading!
Fred Bortz
Science Books for Young Readers
and
Science Book Reviews