Paradoxes in Time Travel Theories

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What is one major physical hurdle that has been cleared for the prospect of time travel according to the text?

The speed of light (correct)
The existence of parallel universes
Quantum entanglement
The bending of space-time

Who theorized the grandfather paradox according to the passage?

Isaac Newton
Peter Galison
Albert Einstein
René Barjavel (correct)

Why does the text suggest that traveling back in time could pose more challenges than just overtaking the speed of light?

Because the earth's crust would be affected
Because time machines do not exist
Because a paradox like the grandfather paradox could occur (correct)
Because the laws of physics prevent time travel

According to Peter Galison, what has happened to Einstein's relativity theory?

It has been pushed harder than any theory in history (A) Signup and view all the answers

What is one obstacle posed by the grandfather paradox?

Creating a time loop (C) Signup and view all the answers

What did René Barjavel speculate could happen if a time traveler were to kill their own grandfather?

The time traveler would cease to exist (A) Signup and view all the answers

According to Novikov's self-consistency principle, what would be the outcome of time travelers affecting historical events?

Travelers could prevent paradoxes by avoiding inconsistencies. (A) Signup and view all the answers

What distinguishes the many-worlds interpretation of time travel from Novikov's self-consistency principle?

The many-worlds theory posits the existence of alternative pathways. (D) Signup and view all the answers

Why would it be impossible to alter historical records by averting the sinking of the Titanic according to the text?

The historical outcome would remain consistent. (A) Signup and view all the answers

How does the concept of parallel universes connect to time travel, based on the text?

Parallel universes offer alternative pathways for every possible occurrence. (C) Signup and view all the answers

What is the main concept behind Novikov's self-consistency principle in relation to time travel?

Ensuring that events causing paradoxes are avoided. (D) Signup and view all the answers

How does the final hypothesis mentioned in the text efficiently address the grandfather paradox?

By rerouting itself around the grandfather paradox. (A) Signup and view all the answers

What would happen if a person altered their ancestry in ways that obstructed their own birth?

They would still exist in person but their historical identity would be gone. (B) Signup and view all the answers

What does Stephen Hawking believe would enable humans to travel millions of years into the future?

Spaceships exceeding the speed of light. (B) Signup and view all the answers

Why does Hawking mention that bygone eras are off limits for time travel?

It violates the rule that cause comes before effect. (B) Signup and view all the answers

Why does Hawking admit that he used to avoid talking about time travel?

For fear of being labeled as a crank. (D) Signup and view all the answers

What is one reason suggested in the text as to why humans could repopulate Earth in the future?

By traveling millions of years into the future through exceeding the speed of light. (B) Signup and view all the answers

What does Hawking's optimism about discussing time travel suggest?

'These days I'm not so cautious.' (D) Signup and view all the answers