Podcast Summary
The Concept of Time Travel Before and After Einstein: Time travel was once a figment of imagination, but after Einstein's theory of relativity, it became more scientifically grounded, with time elapsing differently based on motion and gravity.
Before Einstein's theory of relativity, the concept of time travel was purely imaginative. However, with the understanding that time is individualistic and elapses differently based on motion and gravity, the idea of time travel became more scientifically grounded. Charles Dickens' novel "A Christmas Carol" can be seen as an early exploration of time travel in literature, written long before H.G. Wells' "The Time Machine." Brian Greene, a theoretical physicist and author, explained that our ability to imagine time travel is unique to humans, but what we can say about it today is that time is not universal, and it elapses differently for various individuals based on their motion and the gravity they experience.
Motion and Gravity Affect Time's Passage: Einstein's theory of relativity explains how motion and gravity can cause a moving object's clock to tick more slowly compared to a stationary clock due to the special and general theories of relativity.
According to Einstein's theory of relativity, both motion and gravity can affect the passage of time. When an object is in motion, like a satellite in orbit, its clock appears to tick more slowly compared to a stationary clock on Earth due to the special theory of relativity. However, the stronger gravitational pull on the satellite causes its clock to tick more slowly as well. The net effect is that geosynchronous satellites, despite moving fast relative to Earth, experience time ticking more slowly due to the weaker gravitational pull compared to Earth. This was confirmed in an experiment conducted on a Pan Am jet in the 1970s, where an atomic clock on the tarmac ticked faster than one in the passenger seat due to the difference in gravitational pull. Despite the complexities, Einstein's predictions agree with observations.
Understanding Time and Space with Einstein's Theories: Einstein's theories of relativity affect how we synchronize time on Earth through geosynchronous satellites, and clocks in motion tick off different amounts of time compared to stationary clocks, potentially allowing time travel to the future.
Einstein's theories of relativity have profound implications for our understanding of time and space. These theories require that geosynchronous satellites be pre-corrected for the effects of relativity, allowing us to synchronize time on Earth. Even without gravity, clocks in motion will tick off different amounts of time compared to stationary clocks. This means that a traveler with a clock could theoretically travel into the future and observe a later version of the same place or event. However, the concept of traveling to the past and changing the course of history is a complex issue that Einstein himself did not fully address. Some theories suggest that multiple versions of events exist, and a traveler to the past would be part of the causal chain that led to their own existence. Ultimately, the idea of manipulating the past to alter one's own origin is a paradoxical concept that raises more questions than answers.
The immutable quality of the universe's events: Every event, including our actions, is part of the causal fabric shaping our existence, emphasizing the eternal and unchanging nature of moments in our lives
The events in the universe are inherently unchangeable and immutable. Brian Greene's example of Chuck going back in time to prevent his girlfriend's death only to discover that her death was inevitable, highlights this concept. Even if Chuck tried to alter the timeline, he would only be fulfilling the precise set of events that allowed him to exist in the first place. This idea brings up another proposal, the multiverse theory, where every possible outcome exists in a separate universe. In this context, the immutable quality of the timeline is that all events, including our actions, are part of the causal fabric that shapes our existence. This concept, while it may seem fatalistic, is not at odds with Brian's belief in the absence of free will. In Kurt Vonnegut's "Slaughterhouse-Five," the protagonist, Billy Pilgrim, experiences time travel and realizes that his entire life exists simultaneously, and his fate is already preordained. This notion can bring a sense of comfort, as it emphasizes the eternal and unchanging nature of the moments in our lives, even if they may be painful or tragic.
Can a photon travel back in time?: While it's intriguing to consider whether a photon can travel back in time, it's important to remember that they don't have consciousness or experience, and time travel regulations would be necessary to prevent potential paradoxes.
Time travel raises intriguing questions about the nature of time and its regulation. Brian discussed the question of whether a photon, which moves at the speed of light, can travel both forward and backward in time. He proposed two ways to answer this question: from our perception as observers, and from the photon's perspective. While it's poetic to imagine that time would stop from the photon's perspective, it's important to remember that photons don't have consciousness or experience. Tyler raised another philosophical question about how time travel might be policed or regulated if it were possible. He suggested that Hawking's chronology protection conjecture, which proposes that you can't travel to the past, could be a solution to this problem. Overall, the discussion highlighted the complexities and intrigues of time travel and its potential implications.
Kevin de Saint Martin's insights on 'Frequency' and 'Interstellar': Kevin de Saint Martin, a physicist, contributed to the time travel elements in 'Frequency' and praised 'Interstellar' for its accurate depiction of time travel based on Einstein's theory. The robot in 'Interstellar' was appreciated for its simple design.
Kevin de Saint Martin shared his experience being part of the film "Frequency," where he advised on time travel elements and even appeared in different time frames. He also mentioned "Interstellar" as an accurate depiction of time travel based on Einstein's general theory of relativity. The robot in "Interstellar," a big square robot, was another point of interest. Despite forgetting the robot's name, the group appreciated its portrayal as a simple block with appendages. Both films showcase intriguing time travel concepts and scientific accuracy.
The nature of time in the universe: Nobel Prize-winning physicist Kip Thorne's research on gravitational waves and time dilation suggests time is an intrinsic property of space-time, and time travel could involve different observers seeing the timeline move differently based on their positions, potentially involving wormholes and entropy.
Time is not relative to our physical experiences or the effects of gravity on our bodies, but rather it is an intrinsic property of the fabric of space-time itself. Kip Thorne, a Nobel Prize-winning physicist, has explored this concept through his research on gravitational waves and time dilation. If time travel were possible, observers would see the timeline itself moving differently based on their relative positions, potentially involving wormholes as shortcuts through space-time. Information and entropy may also play a role in this phenomenon. While we may not have the technology to observe or experience time travel yet, the theories surrounding it offer intriguing insights into the nature of time and the universe.
Wormholes and Time Travel: Wormholes could potentially allow for time travel, leading to intriguing storytelling possibilities. Not all wormholes may function this way, but the existence of time travel paradoxes doesn't rule out the possibility.
The concept of wormholes becomes much more intriguing when we consider the possibility of time travel. While moving through a wormhole in space is interesting, the real mind-blowing aspect is when there's a time difference between the two openings. This idea, which was explored in the movie "Contact," can lead to fascinating storytelling elements. However, it's important to note that not all wormholes would function like this; some might just be simple holes where you step through and instantly appear at another place and time. The existence of time travel paradoxes does not necessarily preclude the possibility of time travel. Instead, these paradoxes can be circumvented in various ways. Overall, the exploration of wormholes and time travel opens up endless possibilities for scientific discovery and imaginative storytelling.
Time Travel in Fictional Universes and Information in Black Holes: In fictional universes, time travel doesn't change the past in your own world due to parallel universes. In physics, black holes and their effect on information is debated.
When it comes to time travel in fictional universes like Marvel, instead of altering the past in your own universe and creating paradoxes, the stories often involve traveling to parallel universes where similar events occur. This allows for the freedom to change the past without affecting the present in your own world. Additionally, the discussion touched upon the concept of information and black holes. While information may seem intangible, it is carried by particles. The question of whether information is lost or preserved during black hole evaporation has been a topic of debate among physicists. Ultimately, it was suggested that the particles that come out of a black hole do carry the imprint of their earlier configuration and can be used to reconstruct the original information, even if the original object itself does not come out. As for calculating precise trajectories for time travel in the real universe, it was acknowledged that accounting for the expansion of the universe would be a significant challenge.
Accounting for space location in time travel: Time travel isn't just about changing the time, it's also important to consider the location in space to avoid unexpected destinations. Tachyon particles, which might travel faster than light, are a scientific curiosity but have yet to be definitively detected.
Time travel involves not just changing the time but also the location in space. If you don't account for both, you might end up in an unexpected place. For instance, exiting a wormhole in the wrong location in space could result in being on a different planet or even in empty space. This concept is often overlooked in time travel films and stories, but it's crucial for ensuring you end up where you intend to be. Additionally, detecting tachyon particles, which can travel faster than the speed of light, is a fascinating scientific question. While it might seem impossible to measure something going faster than light, there have been claims of such occurrences, like the Italian neutrino anomaly. However, these claims have turned out to be errors in the data, and the particles did not actually travel faster than light. Nonetheless, if such a discovery were made, it would be groundbreaking and would require scientists to reevaluate our understanding of physics.
Exploring the boundaries of time travel and the Big Bang: The idea of traveling before the Big Bang is like reaching the North Pole's limit, while time travel may involve observing parallel universes through wormholes, but the past remains unchanged.
When it comes to time travel and concepts like traveling before the Big Bang or altering the past, the ideas are intriguing but often lack a definitive answer. For instance, the notion of traveling before the Big Bang might be comparable to asking what's north of the North Pole, as we may reach the end of our current understanding and can't go any further. However, there are alternative theories suggesting the existence of a realm before the Big Bang. As for time travel itself, it could involve traversing wormholes to observe parallel universes, but it's crucial to remember that the past remains unchanged, and any differences in the future result from changes made in the present. Overall, these concepts challenge our understanding of reality and time itself, opening up intriguing possibilities for further exploration.
Neil proposes 'Brian Time' on Cosmic Queries: Neil Tyson suggests expanding Brian's role on Cosmic Queries, emphasizing the value of diverse perspectives in scientific discussions.
Neil deGrasse Tyson expressed his interest in having Brian as a regular feature on Cosmic Queries, suggesting they could call it "Brian Time" and market it accordingly. The conversation took place in a friendly and conversational tone, with Neil welcoming Brian and Chuck to the show. The discussion revolved around the idea of creating more time for Brian on the podcast, emphasizing the importance of featuring diverse perspectives in scientific discussions. The conversation also showcased Neil's engaging and approachable personality, making science accessible and interesting to a broad audience.