Can traveling at high speeds in space affect a person's lifespan?

 Fly at 99% the speed of light for ten years, and you'll return to an Earth that has aged 70. You will outlive everyone you left behind, but the journey itself will shorten your life.

This paradox is driven by Albert Einstein's Theory of Special Relativity. The faster you move through space, the slower you move through time relative to a stationary observer. This phenomenon, known as time dilation, creates the famous "Twin Paradox." However, traveling near the speed of light does not increase your personal, biological lifespan. From your own perspective inside the ship, your watch ticks normally, your cells divide at their standard rate, and you will still age and die after your normal 80 to 90 years. You do not live longer; you simply travel into Earth's future.

While the physics of high speed does not inherently extend your biological clock, the environment you must travel through to achieve those speeds actively deteriorates it. Space is fundamentally hostile to human biology.

The primary threat to lifespan in deep space is ionizing radiation. On Earth, the planet's magnetic field and thick atmosphere protect humans from galactic cosmic rays and solar flares. A spacecraft traveling between stars would lack this planetary shield. Without massive, heavy shielding—which makes accelerating to high speeds incredibly difficult—deep space travelers would be bombarded by high-energy particles. This radiation tears through DNA, causing severe cellular damage, significantly increasing the risk of fatal cancers, and accelerating degenerative diseases like cataracts and heart disease.

Furthermore, if a spacecraft is coasting at high speed, the astronauts inside are in a state of continuous freefall, or microgravity. Prolonged weightlessness causes the human body to atrophy. Without gravity constantly pulling on the skeleton and musculature, bone density drops rapidly, muscles waste away, and the cardiovascular system weakens because the heart no longer has to pump blood against gravity. Even with strict daily exercise regimens, astronauts returning from just a few months in low Earth orbit require extensive rehabilitation.

Ultimately, space travel at relativistic speeds alters when you die relative to the calendar on Earth, but it does not buy you more years of life. Physics shifts your timeline, while the harsh realities of space will likely take years off your natural biological lifespan.

Astronauts Robert Curbeam and Christer Fuglesang conduct a spacewalk during the STS-116 mission in 2006. The extreme environment of space subjects the human body to radiation and microgravity, both of which accelerate biological damage. Source: Wikimedia Commons.

What is the lifespan of a crocodile?

 Crocodiles can live up to 100 years, but they do not die of old age!

After a certain age, they simply stop feeding and die of starvation.

edit:

It's true that I forgot to explain how that's possible. So here's the clarification:

Crocodiles are constantly growing; the older they get, the bigger they are, but the bigger they get, the more they need to eat.

Thus, there comes a point where they simply cannot hunt enough food anymore.

But does that mean that, theoretically, a crocodile in a zoo with a good diet would be immortal?

Yes, but that's only in theory. When a crocodile gets very, very old (and therefore very, very large), its legs don't have enough strength to lift its body (which weighs over a ton). And when the crocodile can no longer move, it refuses to eat, even if you put food directly in its mouth, and will simply starve to death.

LIFESPAN OF LORD BRAHMA

 Do you know Lord Brahma is not immortal? Yes, with time passed, he will eventually die. His age is 100 years. But, these 100 years are not the same as human 100 years; this is 100 divine years of Brahma. Let’s discuss today about Lord Brahma’s Life Cycle.

After being born from GARBHODAKASAYI VISHNU, Lord Brahma created his Universe. His age is 100 Divine years. 1 year of Brahma has 360 days. 1 Day of Brahma is called a KALPA. Each Kalpa has 14 Manvantaras. Each Manvantara has 71 Mahayugas. Each Mahayuga has 4 Yugas. Satya, Treta, Dwapara, and Kali Yuga. After this, Lord Brahma will die, and his universe will be consumed by the inhalation of MAHA VISHNU.

So, the 4 yugas are classified as 4:3:2:1 on the basis of time. So, Kali Yuga will last 432,000 years. So, the Dwapara Yuga’s length is twice that of the Kali Yuga, which is 864,000 years. Same for Treta Yuga, its length is 1,296,000 years. And the length of the Satya Yuga is 1,728,000 years. So, the total length of 1 Mahayuga is 4,320,000 years or 4.32 million years. Now, imagine 1 Manvantara has 71 such Mahayugas, and 1 Kalpa has 14 Manvantaras. How gigantic the number is. So, if we do all the mathematical calculations, then the total time of Lord Brahma’s life is 311 trillion and 40 billion years. Yes, that number of years is equal to 100 divine years of our Brahma. And, also, this huge number is the difference between MAHA VISHNU’S EXHALATION & INHALATION. JUST IMAGINE!!!

So, this is a brief overview of the timeline of Lord Brahma. Our current best theory about the origin of the Universe is the Big Bang Theory, which states that the age of our Universe is 13.72 billion years. If you learn something new from this, please UPVOTE this post and don’t forget to follow my space MINDVERSE.

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Source - Srimad Bhagavatam