Cosmo_Ken

I saw an article on the internet within the past week about a scientific paper that was published on November 22 in the Astrophysical Journal by Swiss astrophysicist André Maeder, raising the question does Dark Matter really exist and proposing an alternative theory to fit the observations, interesting, see: https://www.space.com/39001-dark-matter-doesnt-exist-study-suggests.html?utm_source=sdc-newsletter&utm_medium=email&utm_campaign=20171208-sdc And on the subject of Dark Energy, is it real or is there something fundamentally wrong with the assumptions. What was the exact methodology that the astronomers used to conclude that the expansion of the universe is accelerating, not slowing down?

Interesting. Thanks.

Thanks.

What about daily surface temperature ranges on Mars, at the equator and at the poles???

Thanks!

I realize that this is probably not the best forum to ask this question, but I thought some of you might know the answer.

Thank you Mordred and Strange, you have given me a number of links to check out! I have two other questions. First, so a recent NASA press release that said that they had observed the most distant galaxy yet, at a distance of 13.8 billion light-years, was wrong? Secondly, is the red-shift we observe with most galaxies strictly the result of the relative motion of the galaxies relative to space, or does it include the effect of the expansion of space too? Cheers. What is "60 e folds"?

But was this background microwave radiation emitted at the time of the start of the big bang or is it from the universe itself "currently" radiating in the microwave region of the electromagnetic spectrum because of the universe's "current" temperature???

Has space expanded that much??? What rate of expansion of space has occurred as a function of time since the BB started? Is it still expanding?

How can the universe be around 96 billion light-years in diameter, since it is supposed to be just over 13 billion years old, this would require the average expansion rate since the big bang of more than the speed of light, i.e. expanding at an average rate equal to the speed of light would result in a diameter of about 27 billion light-years, not 96???

There are things about cosmology that I just don't understand! Microwave Background Radiation is one of them. We are told that this is an extremely uniform residual from the Big Bang and that it indicates that the early universe (before stars formed) was extremely uniform. How can it be as uniform as reported, don’t stars, galaxies and even planets (like Jupiter) emit radiation in the microwave band? Wouldn’t microwave radiation emitted by the Big Bang at the time traveled far beyond us ages ago??? If they are talking about a “current” (more or less) afterglow from the universe, i.e. thinking of the entire universe as a Black Body Radiator as it has cooled since the start of the BB, the same question above still applies and also what exactly is the source of this “current” microwave radiation???

If as you say, the universe has been accelerating for the last 5 billion years, this would result in a higher velocity of expansion profile during those 5 billion years than in the previous model, so that has to result in a difference. The universe would take less time to get to its current size than in the old model.

My reasoning is that prior to the discovery of the accelerating expansion, the model would have had deceleration from the end of inflation until now, resulting in lower velocity of expansion as a function of time. With the discovery of accelerating expansion, the velocity of expansion would have been increasing with time and would thus have taken less time for the universe to get to its current state (size), i.e. it must be younger than in the previous model???

If it is correct that the expansion of the universe is accelerating, it seems that this would imply that the universe is not as old as previously thought? This would lead to the conclusion that the most distant galaxies are not as far away as we previously thought, obviously they can not be older than the universe itself? Do they have a model for the rate of expansion as a function of time post the above discovery, i.e. has it been accelerating ever since inflation?

Thanks, that helps a bit, but how did Kepler figure out the orbits? I am sure that the book I ordered will have a bunch of stuff on Kepler, etc. It is called "The History of Planetary Astronomy, Part B: From the Renaissance to Astrophysics".