Is Time Travel Possible?

The Short Answer:

we do know that clocks on airplanes and satellites travel at a different speed than those on Earth.

[{"selector":"#anim-6c17b704-2037-4a86-b372-8ed6e01b9bfc","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-e3a3fc30-1936-4e88-9062-cfb600ed6def","keyframes":{"transform":["translate3d(112.30768%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

We all travel in time! We travel one year in time between birthdays, for example.

[{"selector":"#anim-a9f75f8d-1b26-4e3a-b901-d993491b923a","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-d4c31262-0850-443e-aca7-22fdedfcbccb","keyframes":{"transform":["translate3d(113.23076%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

And we are all traveling in time at approximately the same speed: 1 second per second.

[{"selector":"#anim-02ef7f76-90dc-4571-a8e6-e104389ceb04","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-67283038-b10a-468b-86f0-29e2ffe2e8b8","keyframes":{"transform":["translate3d(113.84615%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away.

[{"selector":"#anim-f2eeaed2-0e26-4db6-a4db-4acc9b95ffb0","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-a3c99efa-0501-4415-a58a-dfe739d988ad","keyframes":{"transform":["translate3d(114.76922%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope,

[{"selector":"#anim-3debf109-864d-45cb-bd08-8c6ed84cdf82","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-388bad7a-1af7-4f5c-83ec-6ab9ce4dc4ca","keyframes":{"transform":["translate3d(114.76922%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

we are seeing what those stars and galaxies looked like a very long time ago.

[{"selector":"#anim-abc34583-d36b-4015-a5c7-8a6671ff392e","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-1416a945-6723-4b73-86dc-b0885244e006","keyframes":{"transform":["translate3d(112.30768%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second.

[{"selector":"#anim-17ba3b05-dfca-4c72-af53-a17f4728f299","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-063fea42-060f-4541-a711-0bc71d1974da","keyframes":{"transform":["translate3d(113.23076%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

[{"selector":"#anim-90e000fc-abea-4272-868c-482f10064c6d","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-38bd11f7-3352-4d54-b364-f54af45432e6","keyframes":{"transform":["translate3d(112.30768%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

How do we know that time travel is possible?

[{"selector":"#anim-025f04b4-146b-421b-b15e-e7abd16b1da3","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-8c9ecac1-43fe-4e13-9a3d-de8b5949ac7f","keyframes":{"transform":["translate3d(114.46153%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-86f3757e-99e8-48be-a54f-e5f819a57eab","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-a6177e5e-c8de-4b96-8173-4f70b7c35068","keyframes":{"transform":["translate3d(114.46153%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

How do we know that time travel is possible?

[{"selector":"#anim-ef78f80c-3274-47a4-8af6-e8564c2239cb","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-80fc631d-871f-45fe-8c30-92a6880ecec9","keyframes":{"transform":["translate3d(114.46153%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-22103a54-b4e6-4667-b765-db5fd4737d71","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-e8c4e2b4-59b6-4278-abcb-f71ef92ec34a","keyframes":{"transform":["translate3d(114.46153%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

How do we know that time travel is possible?

[{"selector":"#anim-17b00481-93c8-4752-bf96-44d0c4e8ad8a","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-2b8e854c-bdd0-469f-8a48-a4a09c5f6a8e","keyframes":{"transform":["translate3d(114.46153%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-b29b1380-fd14-45aa-9c1f-377898fe1be8","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-a4cf9e2c-33b0-424c-8e6c-e55a9ec61a6c","keyframes":{"transform":["translate3d(114.76922%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]