Questioning the universe - Stephen Hawking

Summary

In this enlightening talk, Professor Hawking delves into the origins of the universe, the possibility of alien life, and the future of humanity. He explains the Big Bang theory, the expanding universe, and how recent scientific advancements have blurred the lines between time and space, allowing for a better understanding of the universe's initial conditions. Hawking also discusses the likelihood of life on other planets and the challenges humanity faces in ensuring its long-term survival, advocating for space exploration as a means to extend our existence.

Takeaways

• 🌌 The universe was once thought to be static and unchanging until the discovery of its expansion, leading to the Big Bang theory as the beginning of the universe.
• 🔍 The Big Bang theory suggests that all galaxies were once in close proximity, approximately 15 billion years ago, marking the start of the universe.
• 🤔 Questions about what existed before the Big Bang and the cause of the universe's emergence from the Big Bang remain open mysteries.
• 🔧 The traditional division of the universe's theory into laws of evolution and initial conditions is challenged by the unification of time and space under extreme conditions.
• 🌐 The laws of evolution can now be considered to determine the initial state of the universe, allowing for the possibility of spontaneous creation from nothing.
• 📊 Observations by the WMAP satellite of the Cosmic Microwave Background support the predictions of the universe's creation, showing excellent agreement with theoretical models.
• 🚀 Life on Earth likely arose spontaneously, suggesting that life could potentially appear on other suitable planets, indicating a high probability of life's emergence.
• 🌿 Fossil evidence of life dating back to 3.5 billion years suggests that life on Earth appeared relatively quickly after conditions allowed, supporting the idea of a high probability for life's emergence.
• 👽 Despite extensive searches, no definitive signs of extraterrestrial life or civilizations at our level of development have been detected within a few hundred light years.
• ⚠️ The human race faces increasing dangers due to exponential growth in population, resource consumption, and technological capabilities, which could threaten our survival.
• 🌟 Long-term survival of humanity may depend on our ability to spread out into space, rather than remaining confined to Earth.
• 💪 Professor Hawking emphasizes the importance of seeking a complete theory of the universe and the progress made towards understanding it, despite the challenges.

Q & A

What was the prevailing belief about the universe before the 1920s?

Before the 1920s, it was believed that the universe was essentially static and unchanging over time.

What discovery led to the understanding that the universe is expanding?

The discovery that distant galaxies were moving away from us indicated that the universe is expanding.

What does the term 'Big Bang' refer to in the context of the universe?

The 'Big Bang' refers to the beginning of the universe, the moment when all matter and energy came into existence approximately 15 billion years ago.

What is the significance of the Cosmic Microwave Background in understanding the universe's early state?

The Cosmic Microwave Background is an imprint of the very early universe and provides evidence that supports the predictions made by the laws of evolution regarding the universe's initial conditions.

How does the possibility of time behaving like another dimension of space affect our understanding of the universe's creation?

When time behaves like another dimension of space, it removes the distinction between time and space, allowing the laws of evolution to also determine the initial state of the universe, suggesting the universe could spontaneously create itself out of nothing.

What is the basis for the belief that life could arise on other planets?

The basis for this belief is that life arose spontaneously on Earth, implying that it could also appear on other planets with suitable conditions.

What evidence suggests that the probability of life appearing is high?

The existence of fossils of algae from 3.5 billion years ago, shortly after the Earth's formation, suggests that the probability of life appearing is high, as life emerged relatively quickly after conditions allowed for it.

Why might we not have been visited by aliens despite the possibility of life on other planets?

One possibility is that civilizations do not last very long and may destroy themselves before they can make contact, or they may not be at a stage of development where they can communicate over interstellar distances.

What is the significance of the lack of detected alien television signals in our search for extraterrestrial life?

The lack of detected alien television signals suggests that there are no alien civilizations at our stage of development within a few hundred light years of us.

What does Professor Hawking suggest as the key to humanity's long-term survival?

Professor Hawking suggests that our long-term survival depends on spreading out into space, rather than remaining confined to Earth.

What is Professor Hawking's ultimate goal in his quest for knowledge?

Professor Hawking's ultimate goal is to find a complete theory of the universe, which would provide a comprehensive understanding of its laws and behavior.

Outlines

00:00

🌌 The Origins and Expansion of the Universe

This paragraph delves into the origins of the universe, questioning its inception and the possibility of life beyond Earth. It discusses the discovery of the universe's expansion, leading to the Big Bang theory, and ponders the conditions preceding this event. The speaker also touches on the evolution of the universe's understanding, moving from separate laws of physics to a unified framework where time and space are intertwined, allowing for the spontaneous creation of the universe from nothing. The paragraph concludes with the remarkable alignment of these theories with observations of the Cosmic Microwave Background by the WMAP satellite.

05:00

👽 The Quest for Extraterrestrial Life and Humanity's Future

The second paragraph addresses the probability of extraterrestrial life, considering the rapid emergence of life on Earth as indicative of its potential elsewhere in the galaxy. It humorously dismisses UFO sightings and the lack of evidence for alien civilizations at our stage of development. The speaker then shifts focus to the future of humanity, highlighting the challenges posed by population growth, resource depletion, and technological advancements paired with ancient survival instincts. The narrative emphasizes the importance of space exploration for the long-term survival of our species, advocating for manned space flight as a step towards this goal. The speaker reflects on personal achievements and the pursuit of a complete theory of the universe, ending with a cautionary note on the precariousness of human civilization's longevity.

10:00

👏 A Salute to Professor Hawking's Insights

The final paragraph is a brief acknowledgment of applause, presumably for Professor Hawking's presentation. It signifies the end of the lecture and the audience's appreciation for the profound insights shared regarding the universe's mysteries, the search for extraterrestrial life, and the future of humanity.

Keywords

💡Universe

The universe refers to the totality of space, time, matter, and energy that exists. In the video, the universe is central to discussions about its origins and the possibility of extraterrestrial life. The script mentions the universe's expansion and the Big Bang theory, which posits that the universe began from a singularity around 15 billion years ago.

💡Big Bang

The Big Bang is the prevailing cosmological model that explains the origin of the universe. The script describes it as the event where all matter was condensed into a single point and then expanded, marking the beginning of the universe as we know it.

💡Cosmic Microwave Background

The Cosmic Microwave Background (CMB) is the thermal radiation left from the early universe. It is considered an imprint of the very early universe and is used in the script to illustrate how current scientific observations align with theoretical predictions about the universe's initial conditions.

💡General Relativity

General relativity is a theory of gravitation proposed by Albert Einstein, which has been fundamental in understanding the large-scale structure of the universe. In the script, it is mentioned alongside quantum theory as a framework that allows for the consideration of time as another dimension of space.

💡Quantum Theory

Quantum theory, or quantum mechanics, is a fundamental theory in physics that describes the behavior of matter and energy at the smallest scales. The script discusses how quantum theory, in conjunction with general relativity, can influence our understanding of the universe's initial state and its evolution.

💡Extraterrestrial Life

Extraterrestrial life refers to life that originates outside of Earth. The script explores the possibility of such life, questioning whether we are alone in the universe and discussing the potential for life on other planets.

💡SETI

SETI stands for Search for Extraterrestrial Intelligence. It is an initiative that actively searches for signs of intelligent extraterrestrial life. The script mentions SETI in the context of not having detected any alien civilizations within a few hundred light years of Earth.

💡Fossils

Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The script refers to fossils of algae from 3.5 billion years ago as evidence that life appeared on Earth relatively quickly after conditions allowed for it, suggesting a high probability of life emerging on other planets.

💡Selfish and Aggressive Instincts

These instincts are part of human nature and are discussed in the script as potential threats to the long-term survival of the human race. They are remnants of past survival strategies that may not be beneficial in the context of modern civilization and its challenges.

💡Space Exploration

Space exploration is the ongoing discovery and investigation of outer space by humans. The script argues for the importance of space exploration and colonization as a means for the long-term survival of humanity, given the challenges and limitations of Earth.

💡Manned Space Flight

Manned space flight refers to space travel with humans on board. The script expresses support for manned space flight as a step towards ensuring humanity's future in space, which is seen as crucial for our survival beyond the next hundred years.

Highlights

The universe is expanding, with distant galaxies moving away from us, indicating a common origin.

The Big Bang theory suggests the universe began around 15 billion years ago from a singularity.

The question of what existed before the Big Bang or what caused the universe to emerge as it did is still a mystery.

Traditionally, the laws of physics and the initial conditions of the universe were considered separate; however, under extreme conditions, they may not be.

The possibility that the universe could have spontaneously created itself out of nothing is suggested by combining general relativity and quantum theory.

Observations by the WMAP satellite support the predictions of the universe's creation from different initial states.

The probability of life appearing on Earth suggests it could be common on other suitable planets.

Fossil evidence indicates life appeared on Earth within half a billion years of it being possible, implying a high probability of life emerging.

The lack of observed alien civilizations suggests they may not be common or may not last long.

The SETI project's failure to detect alien transmissions indicates the absence of nearby civilizations at our stage of development.

The future of the human race may depend on our ability to spread out into space to ensure long-term survival.

Human population growth and technological advancement pose increasing risks, necessitating the exploration of space as a survival strategy.

The human genetic code still carries instincts that were advantageous in the past but may hinder our long-term survival.

Manned or person'd space flight is advocated as a means to secure humanity's future beyond Earth.

The quest for a complete theory of the universe is ongoing, with significant progress made in understanding its evolution.

Professor Hawking's personal journey and contributions to understanding the universe are highlighted, emphasizing the pursuit of knowledge despite physical disability.

The likelihood of Earth being the only civilization within several hundred light years is suggested due to the absence of detected radio waves.

The alternative hypothesis is that civilizations may not last long, potentially destroying themselves.

Transcripts

[Music]

[Applause]

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

[Applause]

you