Questioning the universe Stephen Hawking

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there is nothing bigger older than the

universe the questions I would like to

talk about our one where did we come

from how did the universe come into

being are we alone in the universe is

there alien life out there what is the

future of the human race up until the

1920s everyone thought the universe was

essentially static and unchanging in

time then it was discovered that the

universe was expanding distant galaxies

were moving away from us this meant they

must have been closer together in the

past if we extrapolate back we find they

must have all been on top of each other

about 15 billion years ago this was the

Big Bang the beginning of the universe

but was there anything before the Big

Bang if not what created a universe why

did the universe emerge from the Big

Bang the way it did we used to think

that the theory of the universe could be

divided into two parts first there were

the laws like Maxwell’s equations and

general relativity that determine the

evolution of the universe

given its state over all space at one

time one second there was no question of

the initial state of the universe we

have made good progress on the first

part and now have a knowledge of the

laws of evolution in all but the most

extreme conditions but until recently we

have had little idea about the initial

conditions for the universe however this

division into laws of evolution an

initial

ditions depends on time and space being

separate and distinct under extreme

conditions general relativity and

quantum theory allow time to behave like

another dimension of space this removes

a distinction between time and space and

means the laws of evolution can also

determine the initial state the universe

can spontaneously created self out of

nothing moreover we can calculate the

probability that the universe is created

in different states these predictions

are in excellent agreement with

observations by the WMAP satellite of

the Cosmic Microwave Background which is

an imprint of the very early universe we

think we have solved the mystery of

creation

maybe we should patent the universe

encourage everyone royalties for their

existence I now turned on the second big

question are we alone or is there other

life in the universe we believe that

life arose spontaneously on the earth so

it must be possible for life to appear

another suitable planets of which there

seemed to be a large number in the

galaxy but we don’t know how life first

appeared we have two pieces of

observational evidence and the

probability of life appearing the first

is that we have fossils of algae from

3.5 billion years ago the earth was

formed 4.6 billion years ago and was

probably too hot for about the first

half billion years

so life appeared on earth within half a

billion years of it being possible which

is short compared to the ten billion

year lifetime of a planet of earth type

the suggests that the probability of

life appearing is recently high if it

was very low one would have expected it

to take most of the 10 billion years

available on the other hand we don’t

seem to have been visited by aliens

I am discounting reports of UFOs why

would they appear only to cranks and

weirdos if there is a government

conspiracy to suppress the reports and

keep for itself the scientific knowledge

the aliens bring it seems to have been a

singularly ineffective policy so far

furthermore despite an extensive search

by the SETI project we have heard any

alien television quiz shows this

probably indicates that there are no

alien civilizations at our stage of

development within a radius of a few

hundred light years issuing an insurance

policy against abduction by aliens seems

a pretty safe bet this brings me to the

last of the big questions the future of

the human race if we are the only

intelligent beings in the galaxy we

should make sure we survive and continue

but we are entering an increasingly

dangerous period of our history our

population in our use of the finite

resources of planet Earth are growing

exponentially along with our technical

ability to change the environment for

good or ill

but our genetic code still carries the

selfish and aggressive instincts that

were a survival advantage in the past it

will be difficult enough to avoid

disaster in the next hundred years let

alone the next thousand or million our

only chance of long-term survival is not

to remain in red lurking on planet earth

but to spread out into space the answers

to these big questions show that we have

made remarkable progress in the last

hundred years but if we want to continue

beyond the next hundred years our

futures in space that is why I’m in

favor of manned or should I say person’d

space flight all my life I have sought

to understand the universe and find

answers to these questions I have been

very lucky that my disability has not

been a serious handicap indeed it has

probably given me more time than most

people to pursue a quest for knowledge

the ultimate goal is a complete theory

of the universe and we are making good

progress thank you for listening

professor if you had to guess either way

do you now believe that it is more

likely than not but we are alone in the

Milky Way as a civilization of our level

of intelligence or higher

this this answer took seven minutes and

really gave me an insight into the

incredible act of generosity this whole

talk was for Ted

I think it quite likely that we are the

only civilization within several hundred

light years otherwise we would have

heard radio waves the alternative is

that civilizations don’t last very long

but destroyed themselves professor

Hawking thank you for that answer we

will take it as a salutary warning I

think for the rest of our conference

this week professor we really thank you

for the extraordinary effort you made to

share your questions with us today

thank you very much indeed

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you