steady state theory

 steady state theory






in the 1920s, was the first to conjecture a steady state cosmology based on a hypothesized continuous creation of matter in the universe.^[1][2] The idea was then revised in 1948 by Fred Hoyle, Thomas Gold, Hermann Bondi and others. The steady state theory of Bondi and Gold was inspired by the circular plot of the film Dead of Night,^[3] which they had watched together. Theoretical calculations showed that a static universe was impossible under general relativity, and observations by Edwin Hubble had shown that the universe was expanding. The steady state theory asserts that although the universe is expanding, it nevertheless does not change its appearance over time (the perfect cosmological principle); it has no beginning and no end.
Problems with the steady-state theory began to emerge in the late 1960s, when observations apparently supported the idea that the universe was in fact changing: quasars and radio galaxies were found only at large distances (therefore could have existed only in the distant past), not in closer galaxies. Whereas the Big Bang theory predicted as much, the Steady State theory predicted that such objects would be found throughout the universe, including close to our own galaxy.
For most cosmologists, the refutation of the steady-state theory came with the discovery of the cosmic microwave background radiation in 1965, which was predicted by the Big Bang theory. Stephen Hawking described this discovery as "the final nail in the coffin of the steady-state theory". The steady-state theory explained microwave background radiation as the result of light from ancient stars that has been scattered by galactic dust. However, the cosmic microwave background level is very even in all directions, making it difficult to explain how it could be generated by numerous point sources and the microwave background radiation shows no evidence of characteristics such as polarization that normally associated with scattering. Furthermore, its spectrum is so close to that of an ideal black body that it could hardly be formed by the superposition of contributions from a multitude of dust clumps at different temperatures as well as at different redshifts. Steven Weinberg wrote in 1972,

The steady state model does not appear to agree with the observed d_L versus z relation or with source counts ... In a sense, the disagreement is a credit to the model; alone among all cosmologies, the steady-state model makes such definite predictions that it can be disproved even with the limited observational evidence at our disposal. The steady-state model is so attractive that many of its adherents still retain hope that the evidence against it will disappear as observations improve. However, if the cosmic microwave background radiation ... is really black-body radiation, it will be difficult to doubt that the universe has evolved from a hotter, denser early stage.^[4]

Since this discovery, the Big Bang theory has been considered to provide the best explanation of the origin of the universe. In most astrophysical publications, the Big Bang is implicitly accepted and is used as the basis of more complete theories.

steady state theory

 steady state theory






in the 1920s, was the first to conjecture a steady state cosmology based on a hypothesized continuous creation of matter in the universe.^[1][2] The idea was then revised in 1948 by Fred Hoyle, Thomas Gold, Hermann Bondi and others. The steady state theory of Bondi and Gold was inspired by the circular plot of the film Dead of Night,^[3] which they had watched together. Theoretical calculations showed that a static universe was impossible under general relativity, and observations by Edwin Hubble had shown that the universe was expanding. The steady state theory asserts that although the universe is expanding, it nevertheless does not change its appearance over time (the perfect cosmological principle); it has no beginning and no end.
Problems with the steady-state theory began to emerge in the late 1960s, when observations apparently supported the idea that the universe was in fact changing: quasars and radio galaxies were found only at large distances (therefore could have existed only in the distant past), not in closer galaxies. Whereas the Big Bang theory predicted as much, the Steady State theory predicted that such objects would be found throughout the universe, including close to our own galaxy.
For most cosmologists, the refutation of the steady-state theory came with the discovery of the cosmic microwave background radiation in 1965, which was predicted by the Big Bang theory. Stephen Hawking described this discovery as "the final nail in the coffin of the steady-state theory". The steady-state theory explained microwave background radiation as the result of light from ancient stars that has been scattered by galactic dust. However, the cosmic microwave background level is very even in all directions, making it difficult to explain how it could be generated by numerous point sources and the microwave background radiation shows no evidence of characteristics such as polarization that normally associated with scattering. Furthermore, its spectrum is so close to that of an ideal black body that it could hardly be formed by the superposition of contributions from a multitude of dust clumps at different temperatures as well as at different redshifts. Steven Weinberg wrote in 1972,

The steady state model does not appear to agree with the observed d_L versus z relation or with source counts ... In a sense, the disagreement is a credit to the model; alone among all cosmologies, the steady-state model makes such definite predictions that it can be disproved even with the limited observational evidence at our disposal. The steady-state model is so attractive that many of its adherents still retain hope that the evidence against it will disappear as observations improve. However, if the cosmic microwave background radiation ... is really black-body radiation, it will be difficult to doubt that the universe has evolved from a hotter, denser early stage.^[4]

Since this discovery, the Big Bang theory has been considered to provide the best explanation of the origin of the universe. In most astrophysical publications, the Big Bang is implicitly accepted and is used as the basis of more complete theories.

human system

 important  knowledge

1:What is the name of the biggest part of the human brain?

2:The colored part of the human eye that controls how much light passes through the pupil is called the?

3:What is the name of the substance that gives skin and hair its pigment?

4:The muscles found in the front of your thighs are known as what?

5:True or false? The two chambers at the bottom of your heart are called       ventricles

6:What substance are nails made of?

7:What is the human body’s biggest organ?

8:The innermost part of bones contains what?

9:True or false? An adult human body has over 500 bones.

10:How many lungs does the human body have?

11:Another name for your voice box is the?

12:The two holes in your nose are called?

13:Your tongue is home to special structures that allow you to experience tastes such as sour, sweet, bitter and salty, what is their name?

14:The bones that make up your spine are called what?

15:The shape of DNA is known as?

16:The flow of blood through your heart and around your body is called?

17:The bones around your chest that protect organs such as the heart are called what?

18:What is the name of the long pipe that shifts food from the back of your throat down to your stomach?

19:True or false? Your ears are important when it comes to staying balanced.

20:The outside layer of skin on the human body is called the?

Answers Of The Questions:

1	The cerebrum	2	Iris	3	Melanin	4	Quadriceps
5	True	6	Keratin	7	The skin	8	Bone marrow
9	False (there are 206)	10	2	11	Larynx	12	Nostrils
13	Taste buds	14	Vertebrae	15	A double helix	16	Circulation
17	Ribs	18	The esophagus	19	True	20	Epidermis

human system

 important  knowledge

1:What is the name of the biggest part of the human brain?

2:The colored part of the human eye that controls how much light passes through the pupil is called the?

3:What is the name of the substance that gives skin and hair its pigment?

4:The muscles found in the front of your thighs are known as what?

5:True or false? The two chambers at the bottom of your heart are called       ventricles

6:What substance are nails made of?

7:What is the human body’s biggest organ?

8:The innermost part of bones contains what?

9:True or false? An adult human body has over 500 bones.

10:How many lungs does the human body have?

11:Another name for your voice box is the?

12:The two holes in your nose are called?

13:Your tongue is home to special structures that allow you to experience tastes such as sour, sweet, bitter and salty, what is their name?

14:The bones that make up your spine are called what?

15:The shape of DNA is known as?

16:The flow of blood through your heart and around your body is called?

17:The bones around your chest that protect organs such as the heart are called what?

18:What is the name of the long pipe that shifts food from the back of your throat down to your stomach?

19:True or false? Your ears are important when it comes to staying balanced.

20:The outside layer of skin on the human body is called the?

Answers Of The Questions:

1	The cerebrum	2	Iris	3	Melanin	4	Quadriceps
5	True	6	Keratin	7	The skin	8	Bone marrow
9	False (there are 206)	10	2	11	Larynx	12	Nostrils
13	Taste buds	14	Vertebrae	15	A double helix	16	Circulation
17	Ribs	18	The esophagus	19	True	20	Epidermis