OpenMind

If you are moving relative to someone else, then their clock will appear to be running slower than yours. One result of this is the "Twins Paradox" (not really a paradox, just a surprising result) which shows that if your twin flies off into space and travels really fast for a while then when she comes back she will have aged less than you.

 

So, for example, if you were to travel to a star that is a hundred light years away and you accelerated at a constant 1g half the way and then decelerated at a constant 1g for the rest of the journey then it would take you about 9 years of your time to get there. people on Earth would see that it took you just over 100 years. After doing a bit of exploring, you get back on board and head back to Earth. More than two centuries have passed but you are only 20 years older. Is that time travel? You decide.

 

Yes, I 've heard about that before. What about future human Martians when they go back to earth?

I've read it. I don't see where he disagrees with me. It's hypothetical talk about "what if a time machine was built"

You said: "I think I saw a movie once where this rule was used. This is not science OpenMind, its SciFi."

Tim88...don't you mean that due to time dilation effect someone traveling in a spaceship will end up being younger than his twin brother on earth ?

This concept would most definitely not enable you to "travel" to the 28th century in a sense that OpenMind's video suggests.

 

 

I think I saw a movie once where this rule was used. This is not science OpenMind, its SciFi.

 

This scientist disagrees with you, he says you can only travel back to the time when a time machine was built:

http://news.nationalgeographic.com/news/2013/13/130412-iranian-time-machine-time-travel-grandfather-paradox/

(Not the Iranian guy but the one interviewed here)

Well, if you could achieve sufficient time dilation such that 7 centuries passed on Earth in a few years, days or minutes of your time, then that would effectively be time travel into the future. Or the nearest thing that is actually possible with currently known physics.

What is time dilation?

In principle the problem is not so much that he claims that he traveled to the 28th century, as that can in theory be achieved by slowing down his biological clock. The problem is that he claims to have traveled back in time to our age; it's according to current knowledge impossible, even nonsensical, that he returned from the future.

But if you build a time machine, you can travel back to the point where the time machine is created...

Negative energy is a purely hypothetical concept. There is no evidence that such a thing can exist.

I thought that they proved its existence in a laboratory?

Negative energy is an idea used in quantum mechanics specificaly quantum field theory to explain how fields behave.

Science fiction writers picked up the concept of negative energy and are using it for science fiction purposes like anti gravity.

Heres a video that will help you to get a firmer grip on gravity:

https://www.youtube.com/watch?v=jlTVIMOix3I

 

Interesting video, but the problem is that I didn't learn about this idea from Science-fiction, but scientists. They however added that an immense amount of negativd energy would be needed to move the space around objects, about the size of Jupiter, which makes it practically impossible with our current technology.

 

So as I understand anti-gravity has nothing to do with pressure? Can anti-gravity only be achieved by negative energy? I regularly watch science tv-shows and by negative energy you can levitate things as far as I understood?

Anti gravity is science fiction.

Al Bielek was already suspicious to me, because he sells CDs etc with his story and his story changed over the years, which wouldn't happen when a story is true.

 

As my username says I am Open Minded, therefore I don't immediately dismiss claims like time travel, I mean, according to Karl Popper scientific paradigms can be overthrown, so who knows, maybe in the future we can time travel with new scientific paradigms, but if someone is obviously a fraud, asks a lot of money, changes his/her story they aren't credible to me anymore.Time travel is a far off idea but theoreticaly possible.

 

If anti-gravity is science-fiction what does negative energy do? I thought it does the opposite of normal energy and can 'push away' energy so that it moves a spaceship for instance while the spaceship itself doesn't move at all? It would also turn gravity to anti-gravity.

OpenMind...great that you are aking questions and welcome to the forum. I've been here only a month and a half and I've already learned a lot.

Atmospheric (air) pressure on earth is 1 Bar at sea level. If you take a dive 2m into water you will feel the pressure of about 2 Bar due to the 2m of water above you pushing onto you. Atmospheric pressure is just the density of the air that you are breathing and it's present exactly becasue of the same principle as the water analogy I gave you...a column of air above you is creating this pressure. If you climb a high mountain the air pressure will be much lower there...you can feel that it's harder to breathe because you have to inhale more air into your lungs to get the same amount of oxygen into your lungs as you would being at sea level. The air at higher altitudes is thinner, less dense - it has a lower atmospheric pressure.

Our moon has no atmosphere and has gravity, that should give you a hint.

So as I understand anti-gravity has nothing to do with pressure? Can anti-gravity only be achieved by negative energy? I regularly watch science tv-shows and by negative energy you can levitate things as far as I understood?

Al Bielek was already suspicious to me, because he sells CDs etc with his story and his story changed over the years, which wouldn't happen when a story is true.

As my username says I am Open Minded, therefore I don't immediately dismiss claims like time travel, I mean, according to Karl Popper scientific paradigms can be overthrown, so who knows, maybe in the future we can time travel with new scientific paradigms, but if someone is obviously a fraud, asks a lot of money, changes his/her story they aren't credible to me anymore.

Hi, thanks for your replies. As I 'm critical about things, but have a lack of physical knowledge due to poor education I asked it here.

Could someone explain me the difference between normal pressure and atmospheric pressure? So on a planet with no atmosphere there is zero gravity?

Dear all,

I 'm someone with an open mind interested in urban myths etc.

I found a supposed interview by someone called Al Bielek who claims to have travelled through time. He would have done that in a US military experiment, now it's naive to dismiss all extraordinary claims as there will definitely exist secret technology by the military, though this is quite extraordinary to claim.

I seriously listened to what he said (though most likely fake it's still a fascinating story he had to tell and betterctyan most science-fiction) He said that he travelled to the 22nd and 28th century. He described floating cities in the 28th century.

The relevant part of the interview here in which he describes how it physically worked according to him can be found from 0:48 to 2:28 and he talks about it in some other part too.

Now I want to ask people with knowledge of physics if what he says is complete mumbo-jumbo or if (by coincidence or some physical knowledge which he has) something of what he says is correct.

He also explained how anti-gravity was established by removing the pressure above something, is this correct I ask s a layman and can something lose gravity by removing pressure from above? It seems logical to me.