What is a Wormhole?: "A wormhole is a tunnel-like structure that connects two points in spacetime. Imagine the universe is like a giant piece of paper. Normally, if you want to go from one side to the other, you have to travel across the paper. But what if you fold the paper so both sides touch? A wormhole is like that fold, connecting two faraway points in space and time, so you can travel between them faster than if you were just going to travel."

Unstable: Wormholes might be unstable, meaning they could close up before you even get through them, or they might rip you apart because of the intense force.

"If traversable wormholes exist, they might allow time travel.[34] A proposed time-travel machine using a traversable wormhole might hypothetically work in the following way: One end of the wormhole is accelerated to some significant fraction of the speed of light, perhaps with some advanced propulsion system, and.."

Read more --> https://en.wikipedia.org/wiki/Wormhole

 

General Relativity Explained: General Relativity and Time:
Einstein's theory of general relativity describes gravity not as a force but as a curvature of space-time caused by mass and energy. This curvature affects the passage of time, leading to time dilation.  How would this prove Time Travel or Wormholes?:  GR equations allow for wormholes, tunnels connecting two distant points in spacetime. If one end moves at near-light speed while the other stays still, time at each end moves differently, creating a possible "time machine. "Problem: We don’t know if stable wormholes exist or how to keep them open

 

Notes From sources: "Spacetime: Einstein's theory combines space and time into a single, four-dimensional entity called spacetime. Curvature: Mass and energy warp or curve this spacetime fabric. Gravity as a consequence: Objects move along the curves in spacetime, which we perceive as gravity. Analogy: Imagine a trampoline. If you place a heavy ball on it, it creates a dip. If you then roll a marble near the ball, it will curve towards the ball, not because of a force but because of the trampoline's curvature.  

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Equivalence Principle: The theory also states that the effects of gravity are indistinguishable from the effects of acceleration, meaning that an observer in a closed elevator accelerating upwards would feel the same sensation as an observer standing on Earth experiencing gravity. 

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Time dilation" Explanation - "Time dilation means that time does not pass at the same rate for everyone—it can slow down depending on speed and gravity. If someone is moving very fast or is in a strong gravitational field, time for them will pass more slowly compared to someone who is stationary or in a weaker gravitational field. " Gravity and Time: The stronger the gravitational pull, the slower time moves. If you were near a black hole, time for you would pass much more slowly compared to someone far away from it.
Speed and Time: The faster you travel through space, the slower time passes for you relative to someone who is not moving.

The science of time. Example: "Think of time like a river. Normally, it flows at the same speed everywhere. But if the river goes around a huge rock (like a strong gravitational field) or speeds up downhill (like moving fast), the flow changes—it slows down in some places and speeds up in others. Time works the same way. If you're moving really fast (like near the speed of light) or near something with strong gravity (like a black hole), time slows down for you compared to someone else in a normal place. This happens because space and time are connected, and when one gets stretched or bent, time changes its flow."

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The science of time. Example: "Think of time like a river. Normally, it flows at the same speed everywhere. But if the river goes around a huge rock (like a strong gravitational field) or speeds up downhill (like moving fast), the flow changes—it slows down in some places and speeds up in others. Time works the same way. If you're moving really fast (like near the speed of light) or near something with strong gravity (like a black hole), time slows down for you compared to someone else in a normal place. This happens because space and time are connected, and when one gets stretched or bent, time changes its flow."

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"Space and Time are Interwoven: Einstein's theory of relativity, especially general relativity, proposes that space and time are not separate entities but are interwoven into a single fabric called spacetime".  Another way that it can affect you is that the faster you travel through space, the slower time passes for you relative to someone stationary. So if I were to be sent into a black hole and some scientists from Earth were watching me as I sped up because of the massive gravitational pull, I would eventually go so fast I would slow down time, and it would look like I was going slower and slower until, eventually, I would go so slow it would look like I stopped.  How does this affect us?- Massive objects warp this fabric, influencing how objects move and how time passes.  Imagine that two people are holding the sides of a blanket above the ground. That would be the space-time, and if you put a metal ball in the center, it will make an indent. So if you put marbes around the edge of the blanket, they will roll in a circle or oval pattern until they reach the metal ball in the middle.  This is how we orbit our sun, and it's also how black holes work.

 

What are some paradoxes that could happen?: Grandfather paradox- Imagine you go back in time and accidentally (or purposely) stop your grandfather from meeting your grandmother. If that happens, your parent—and you—would never be born. But if you were never born, how did you go back in time to stop him in the first place? It creates a loop with no answer, where cause and effect don’t make sense.

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The Predestination Paradox

In this paradox, going back in time causes the thing you're trying to prevent. For example, if you travel back in time to stop a disaster, your actions end up accidentally causing the disaster instead. It feels like fate can’t be changed—no matter what you do, the timeline fixes itself.  

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Do you have free will?- Causality and free will are important ideas when talking about time travel. Causality means that one event causes another, like how studying leads to getting a good grade. Normally, causes happen before effects. But if someone traveled back in time, they might cause something to happen before its original cause. This creates a time loop and makes it hard to tell what came first. That’s where the idea of free will becomes confusing. If the past cannot be changed, then everything you do while time traveling may have already happened. This means your choices were never really your own—they were part of a fixed timeline. Some scientists agree with this and believe time travel must follow rules that avoid paradoxes. Others think changing the past could create new timelines where different outcomes exist. If that’s true, you could still have free will, just not in the timeline you came from. Time travel challenges how we think about cause and effect and whether our choices really matter

Parallel universes: Parallel universes are the concept that there are multiple, potentially infinite, realities existing alongside our own. Each universe may have slight or significant differences in events, outcomes, and even the laws of physics. Time travel could potentially create or interact with these parallel worlds. When you travel back in time and make changes, you don't necessarily alter your own timeline but instead create a new, separate reality or parallel universe. This is sometimes called the "multiverse theory" or "many-worlds hypothesis." The idea is that your actions in the past might split off from your original timeline, resulting in a new reality with different events and outcomes, while your original timeline remains unchanged. So, the changes you make affect a different version of reality, not the one you came from.

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Twin Paradox:- The Twin Paradox is a thought experiment in Einstein’s theory of special relativity that shows how time can pass at different rates for people moving at different speeds. In the scenario, one twin stays on Earth while the other travels on a spaceship at nearly the speed of light to a distant star and then returns. When the traveling twin comes back, they are younger than the twin who stayed on Earth. This seems strange because, from each twin’s point of view, the other is the one who was moving. However, the key difference is that the traveling twin changes direction and accelerates to return home, while the Earth-bound twin does not. This breaks the symmetry and explains why the traveling twin experiences less time, something called time dilation. Time dilation is a real, proven effect of moving close to the speed of light. In fact, scientists have tested this with highly accurate atomic clocks placed on fast-moving airplanes and satellites, and the clocks showed less time had passed compared to those that stayed on Earth. So, while the Twin Paradox sounds like science fiction, it actually reveals how time itself can stretch and shrink depending on how you move through space.

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Suummary - Time travel is theoretically possible according to Einstein’s theory of general relativity, which shows that time can slow down near strong gravity or at high speeds. While traveling into the future has been proven in small ways through time dilation, going back in time is still only hypothetical, possibly requiring stable wormholes or exotic matter. If time travel became real, it could cause major challenges, like paradoxes (changing the past and affecting your own existence), ethical problems, and shifts in how we think about free will and cause and effect. It might also lead to new timelines or parallel universes. As a society, time travel could change history, law, technology, and our understanding of reality, raising questions about who controls it and whether our choices truly matter.