Why do Science textbooks not consider Evolution as fact?

Question

Why do they always say things like "Prehistoric apes are widely considered to be the ancestors of modern humans" instead of "they are the ancestors of modern humans". Or "The Universe is thought to have come into existence 13.7 Billion years ago in the Big Bang" instead of simply "The Universe came into existence 13.7 Billion years ago in the Big Bang"

Answer 1

Because on things like these are still not neccessarily "proven", most are still just theory's (even though we know they are pretty much true) so we can't call them facts just yet until we get definate proof. As for how old the universe is, that is another guess found by measuring the expansion of the universe. They can never get an exact figure that they know is correct by using this method. That is why they use the words like "thought" and "considered" when stating these assumptions. Hope i helped. :)  

Answer 2

Because it's a theory, not a fact.

Answer 3

Because these things cannot be proved scientifically.

Answer 4

i doubt any scientist can predict the exact day of the birth of the universe do you - thats why they say "around 13.7 billion years"

As for the ape, its because we may have evolved from something alot earlier, and the "prehistoric ape" also evolved from that.

These statements are made without 100% certainty, and what do you expect, your looking into literally the history of the earth, you any idea how big that is?

Answer 5

Consider than all they have is evidence and have not seen these things happening. In this way it is like a trial. Were each side puts forward a theory which events are imbued upon the evidence. This is a theory. Theories are used compared with their relative corroboration with the evidence and basically there ability to explain phenomena. For example the theory of relativity is unable to explain so phenomena yet it is still the best theory available to explain most phenomena. If a new thoery emerged that was corroborate more and could explain more it would be adopted.

The big bang is based on evidence of galaxies moving apart. It is unable to explain why however matter is unevenly distributed through the universe and why matter remains in galactic clusters. Dark matter is a thoeretical invention to plug the hole in the theory but one could question it. Yet the big bang is the best theory as of date to explain the way in which bodies in the universe are acting.

Answer 6

Because we know that evolution does happen...and all the hoping and wishing in the world cannot change the fact that it has been well documented.

Evolution as a theory refers to why it happens. Is it random? Is it natural selection? Is there a higher power pushing genes and stars around in a calculated way? Scientists can't *prove* why it happens so it stays a scientific theory.

"The Theory of Evolution is the explanation for all relevant observations regarding the development of life, based on a model that explains all the available data and observations. Thus, evolution is not only a fact but also a theory, just as gravity is both a fact and a theory."

Cite: Evolution As Theory and Fact, Wikipedia