If our universe is 4.6 billion years old as some scientist suggest, than our sun is halfway through it's?

Question

10 billion year life expectancy. As stars get older, they also get brighter. Our sun is supposedly 40% brighter than it was 4.6 billion years ago. If we go back 3.5 billion years to when life supposedly first started, the sun would have been 25% bright than it is now. The sun being less bright, also means less heat was produced. This less heat would have lowered the temperature of the earth from an average 59 degrees to an average below freezing.
Can anyone explain how life would have started with average temperatures below freezing?

Answer 1

our universe is way older than 4.6 billion years, you are talking about earth.

the incorrect assumption that atmospheric gas concentrations in the past were the same as today. First, before the advent of abundant life the atmospheric oxygen concentrations were orders of magnitude lower than today. In the presence of oxygen methane breaks down to carbon dioxide, so in the absence of oxygen the methane concentration could be much larger than currently observed. Methane is a more potent greenhouse gas than carbon dioxide, so the relative abundance of atmospheric methane throughout the history of Earth must be considered when modelling the temperature.

Answer 2

The Universe is estimated to be more than 14 billion years old, not 4.6 billion. The 4.6 billion is the estimated age of earth.

The sun may be 50% through its life span as a yellow dwarf-type star, but it has 5 billion years to go and it may go on much longer as a white dwarf.

Your comments about earth's temperature are speculation. The earth has been losing heat from its own formation so it would likely have been warmer in its infancy from geologic and formation processes. In addition, there was likely more of a greenhouse gas effect before plant life took hold to convert the atmoshphere.

Life processes probably don't need temperatures over freezing. Much life in the ocean exists at temperatures of less than 32 degrees Farenheit -- sea water requires much lower temperatures to freeze due to its chemical makeup. Thermal vents in the ocean support life even in the absence of sunlight and heat, warmth being provided by the thermal vent. There is no reason to think conditions were that different or that such islands of life in severe conditions did not exist previously.

Answer 3

OK, um... your info is a little off, there. 4.6 billion is the age of the Earth, not the sun or the universe. the universe is something like 11 or 12 billion years old. the sun was formed some time after, I'm not sure of the exact figure. also, where are you getting these figures anyway? i doubt they are reliable, no offense, because the prevailing scientific theories nowadays would not overlook something so basic.

Answer 4

Posting a science question in the religion and spirituality section often means the asker does not really want an answer. His goal is to ask a question that he believes proves some scientific knowledge to be wrong, or that science does not yet answer, and make the implicit claim that the only other explanation is a god, and specifically, the same god he happens to believe in.

It's the "god of the gaps" - intellectually bankrupt, since it favors ignorance instead of knowledge, and because of the contained logical fallacy.

However, on the off chance that you really want to know the answer:

Your numbers are off (for example, the universe is three times as old as you think) and your assumption about intensity as a function of age is completely flawed.

If you really want an answer, post in the right category next time.

Answer 5

stars
http://www.nasa.gov/worldbook/star_worldbook.html
life
http://map.gsfc.nasa.gov/m_uni/uni_101life.html

*sigh* - the basics

hmm...the sun and the earth are both part of the solar-system and therefore would have started to form at almost similar times, on the cosmological scale, therefore the Earth would have begun to warm up relative to Sol, our star. But then you are not taking into account the heat generated from the initial formation of the Earth, all that matter clanking, clumping together, the rubbing of materials on that scale must create a little friction, the Earth after all is not solid all the way through...What do you think?

Answer 6

There's a difference between the freezing point and absolute zero - the lowest temperature possible. Absolute zero is −273.15 °C. Above this temperature, energy and life can still exist.

Alternatively, if you believe God created the world then the laws of physics are irrelevant anyway. They could have steered evolution comfortably at -270°C if he wanted to.

Answer 7

tell me, how would we know the life expectancy of a star is about 10 billion years if the universe is 4.6 billion years old?

Answer 8

This is faulty logic to begin with. The theory is not that all stars came to exist at once - rather, stars continuously die, and new stars are eventually born from the remnants.

Answer 9

Adaptation, cold blooded creatures and warm blooded creaturess, both addapted to the correct weither untill evolution came to this point where humans can survive very harsh weathers hot and cold

Answer 10

Something that evolution scientists can't explain. Abiogenesis requires heat, but the earth 3.5 billion years ago would have been a giant ice cube.