Was Einstein Wrong about Space Travel?

[C1ay]

Consider a pair of brothers, identical twins. One gets a job as an astronaut and rockets into deep space. The other stays on Earth. When the traveling twin returns home, he discovers he's younger than his brother.

 

lefthttp://hypography.com/gallery/files/9/9/8/albert-einstein_thumb.jpg[/img]This is Einstein's Twin Paradox, and although it sounds strange, it is absolutely true. The theory of relativity tells us that the faster you travel through space, the slower you travel through time. Rocketing to Alpha Centauri—warp 9, please—is a good way to stay young.

 

Or is it?

 

Some researchers are beginning to believe that space travel could have the opposite effect. It could make you prematurely old.

 

"The problem with Einstein's paradox is that it doesn't fold in biology—specifically, space radiation and the biology of aging," says Frank Cucinotta, NASA's chief scientist for radiation studies at the Johnson Space Center.

 

While the astronaut twin is hurtling through space, Cucinotta explains, his chromosomes are exposed to penetrating cosmic rays. This can damage his telomeres—little molecular "caps" on the ends of his DNA. Here on Earth, the loss of telomeres has been linked to aging.

 

So far, the risk hasn't been a major concern: The effect on shuttle and space station astronauts, if any, would be very small. These astronauts orbit inside of Earth's protective magnetic field, which deflects most cosmic rays.

 

But by 2018, NASA plans to send humans outside of that protective bubble to return to the moon and eventually travel to Mars. Astronauts on those missions could be exposed to cosmic rays for weeks or months at a time. Naturally, NASA is keen to find out whether or not the danger of "radiation aging" really exists, and if so, how to handle it.

 

Science is only now beginning to look at the question. "The reality is, we have very little information about [the link between] radiation and telomere loss," says Jerry Shay, a cell biologist at the University of Texas Southwestern Medical Center at Dallas. With support from NASA, Shay and others are studying the problem. What they learn about aging could benefit everyone, on Earth and in space.

 

A Lit Fuse

 

Like the fuse of a time bomb, telomeres are long strands of repeating DNA that shorten each time a cell divides. When the telomeres become too short, the cell's time is up: It can no longer divide, a state of affairs known as "replicative senescence."

 

Without this built-in fuse, human cells would be able to continue growing and dividing indefinitely. In fact, scientists believe that cells evolved telomeres as a way of preventing the out-of-control cell growth of cancerous tumors. Because of telomeres, most human cells can only divide 50 to 100 times before the time bomb goes off.

 

One current theory of aging holds that, as the cells of a person's body start to hit this telomere-imposed limit, the lack of fresh, new cells causes the typical signs of aging: wrinkled skin, failing organs, weaker immune system, etc.

 

Whether or not telomere loss actually causes aging remains a matter of debate, Shay notes. The fact that shortened telomeres go hand in hand with aging is well documented. People with shorter telomeres, for example, are known to not live as long on average as people with longer telomeres. But mere correlation doesn't prove whether telomeres are in fact the cause.

 

"It's hard to prove cause and effect in these things. But I think there's a sufficient number of these correlative studies from a variety of different investigators that one has to start believing that short telomeres are a marker of aging," Shay says.

 

Recent research, performed by Frank Cucinotta and colleagues, showed that iron-nuclei radiation (a chief component of cosmic rays) does indeed damage the telomeres of human cells.

 

To prove this, they exposed laboratory dishes containing a kind of human blood cell called lymphocytes to beams of both iron nuclei and gamma rays. Until recently, such a thorough analysis of telomere damage would have been prohibitively time consuming. But a new cell-staining technique called RxFISH (Rainbow cross-species Fluorescence In Situ Hybridization) allowed Cucinotta and his colleagues to look at many telomeres simultaneously.

 

"We had this surprising result that iron particles are much more damaging to telomeres than gamma rays," Cucinotta says. He suggests that this difference might be due to the wider path of damage caused by iron nuclei. Telomere strands wrap into elongated loops, like little knots on the ends of chromosomes. Gamma rays can only strike one side of these loops or the other, but iron nuclei can affect both sides at the same time, inflicting lasting damage on the telomere—possibly causing its complete deletion. This explanation is still speculative, however.

 

The task now is to quantify the risk telomere damage might pose to astronauts, so that mission managers and the astronauts themselves can make informed decisions about the risks they face. In all likelihood, the effects will be modest, Shay says.

 

"We're talking about subtle things. These people are probably not going to wind up in wheelchairs or something like that from being in space," Shay says.

 

For example, astronauts who have had the greatest exposure to space radiation, such as the Apollo astronauts who traveled to the Moon, tend to get cataracts about 7 years earlier than other astronauts, on average. Cataracts are a common symptom of aging.

 

Of greater concern is possible aging of the brain and spinal cord. Experiments with rats have shown that brain tissue is vulnerable to "aging" by iron-nuclei radiation--this according to research by Jim Joseph of Tufts University and Bernie Rabin at the University of Maryland. (See references below.)

 

"It is looking more and more likely that this could be a problem for long-term space travel," Cucinotta says.

 

However, if scientists can tease apart the exact ways that iron-particle radiation affects telomeres, they may be able find a way to avoid or correct it. The solution could be as simple as a pill containing DNA-repair molecules. "There are many ways that we can intervene," Shay says.

 

One way or another, NASA plans to keep their astronauts feeling young.

 

Source: Science@NASA

[InfiniteNow]

Great article C1ay. Nice combination of research in the various sciences. It's a thought I hadn't pondered before, but makes good sense.

[Tormod]

But this article is all bollocks. It suggests that there is something wrong with relativity theory, but it boils down to the fact that radiation is dangerous for human beings (which we already know). They're even saying "there are many ways we can intervene".

 

I fail to see where Einstein comes into this...except as a ploy to sell an article. C1ay, you've been had. :)

[Jay-qu]

yeah thats the feeling I got when reading it Tormod, they are saying that the analogy used by Einstien was incorrect because you would age faster from radiation but it is irrelavent because the time spent by the astronaught would still be less..

[C1ay]

I took it as a tad satirical...

[TheBigDog]

Einstein used as a teaser...

 

I checked the article for invisble text. There was none.

 

Bill

[jpittelo]

I don't see the problem with time travel..Einstein did a lot of thought experiment...this could be just one more...you don't need to experiment the lift (the first lift ?) or free fall to know that it can "simulate" or compensate the gravitational force...So there is no problem by making a thought experiment about travelling in time ?..But do physicists need experiments..is it just imagination enough..?

[Tormod]

I don't see the problem with time travel..Einstein did a lot of thought experiment...this could be just one more...

 

This has nothing to do with thought experiments, but about the studied effect of cosmic radiation on humans who have travelled in space.

 

It is in no way related to Einstein's relativity theory...

[α CMa]

Well the artical is talking about biology and I dont see how Einstine was wrong.I would say he was right with using that analogy.

[Adrian Cobon]

Is radiation not tied down to the same speed of light limit impossed on all matter and energy? Would it not potentially be knocked down a couple notches realitivically speaking to something less dangerous due to our own speed. (Doppler shifting for speeds of galaxies is my train of thought) And would we not need a strong shield on front of the ship to protect from high speed particles that potentially can be designed to block, or even use for energy, rays that are "ran into?"

[C1ay]

Well the artical is talking about biology and I dont see how Einstein was wrong.I would say he was right with using that analogy.

It's only a satirical claim the he was wrong, as a lead in to the story that we have learned since Einstein that radiation is a previously inconsidered variable of space travel. The story is only pointing out that the space traveling twin would be aged by radiation, even if he/she is younger relative to time.