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If such a bubble could be created, there would be no way for those inside the bubble to control, steer, or stop the spacecraft because the ship would be completely isolated from the rest of the universe. For that reason, some have suggested a donut-shape or torus would be a better approach than a bubble. However, that still does not get past the first two major hurdles.
The idea is that such a craft containing its own spacetime would, in effect, be able to pull at or contract spacetime in front of the craft and at the same time push or expand spacetime behind the craft. Just guessing, but if whatever mechanism the craft has in front and back, if the mechanism could swivel in different directions, it would be pulling or pushing at spacetime in different directions which could be a form of "steering". Much easier to say than to do though.
I agree with you though. If the ship is contained inside its own bubble of spacetime, your view of the universe would be very strange. How would you know where you are or where you're going? I guess all the coordinates would have to be preset, and hope for the best. It wouldn't be too great if you ended up in the middle of a star or a planet.
The idea is that such a craft containing its own spacetime would, in effect, be able to pull at or contract spacetime in front of the craft and at the same time push or expand spacetime behind the craft. Just guessing, but if whatever mechanism the craft has in front and back, if the mechanism could swivel in different directions, it would be pulling or pushing at spacetime in different directions which could be a form of "steering". Much easier to say than to do though.
I agree with you though. If the ship is contained inside its own bubble of spacetime, your view of the universe would be very strange. How would you know where you are or where you're going? I guess all the coordinates would have to be preset, and hope for the best. It wouldn't be too great if you ended up in the middle of a star or a planet.
Which is why a torus would be a better approach than a bubble. If the spacecraft were in the center of the torus they would still be part of the universe and able to control the direction of the torus as well as stop. The center of the torus would be normal space, while the front of the torus would create the negative space and the back of the torus would create positive space, thus allowing the spacecraft to "surf" normal space faster than the speed of light. They still would be able to communicate with the torus, allowing them to steer or stop, but the spacecraft would not be able to pass through stars or planets like they could if they were completely encapsulated within a bubble.
If the spacecraft was inside a bubble, then it would be completely removed from the rest of the universe and unable to communicate with the bubble, therefore unable to direct its course or stop once the bubble was created. The bubble would continue upon its predetermined course and speed until it lacked the energy needed to maintain the bubble. The good news is that since they would be disconnected from the rest of the universe they could pass through planets and stars without any effect. The bad news is if they do not have the energy needed, or run out of energy before reaching their desired destination they could appear in the middle of a star or planet.
The energy required to form such a torus or bubble would be astronomical. We are talking about the entire energy of a star just to be able to move an object the size of an atom a few thousand light years faster than light. In order to move a spacecraft a few thousand light years faster than light it would require more energy than an entire galaxy could produce.
There's a lot of "what if's" to that theory, its one I most certainly do not subscribe to. Its full of far too much speculation and guessing that laying down a physical framework for it is unreasonable...
There's a lot of "what if's" to that theory, its one I most certainly do not subscribe to. Its full of far too much speculation and guessing that laying down a physical framework for it is unreasonable...
Ben, you said you're a physicist. Experimental or theoretical? Both are important.
On Page 1, Post 3, you said:
Quote:
Space exists where matter is present.
How would anyone really know? Space may surround matter, but I don't think we can simply assume that if matter is not present, space couldn't exist. We don't know. If there was no matter, there'd be no points of reference for us to use in space. Maybe a better way to say that, along those lines, is that the space of the universe we live in contains matter.
In the same post you said:
Quote:
If our Universe is one "bubble" out of a larger spacial area, then there's even
a chance that we may "run into" another Universe. Think of a bubble bath where
we're one bubble, and other Universes are other bubbles. Sometimes they touch
and interact! Wouldn't that be an interesting situation?
Although your point is certainly valid, 'bubble universes' (a multiverse scenario) are completely unknown to us. We have no idea if there are any other universe-sized structures apart from our own, nor do we have any idea that "Sometimes they touch and interact." That puts it into area of speculation, prefaced by the word "If..."
So how is addressing scenarios about spacecrafts that are torus-shaped or encapsulated in a bubble of spacetime any different than scenarios about bubble universes or whether or not space exists where matter is present?
Don't take that as being an unfair criticism because I think the thread is an excellent one. But I do think it's fair to say that we don't know everything about the universe, and what we do know is subject to change based on new discoveries and information. For example, we're learning new things about the farthest reaches of the solar system that we never knew before that are changing our views. We're learning more about what the surface of Mars is really like. It was almost shocking to see all the craters in the images of the first fly-bys. And we've been learning more about the structure of the universe. We know that the sun does not orbit the Earth and that the galaxy is not the entire universe. We're learning how amazing and at the same time strange the universe is.
Sometimes the things we know about were built on speculations and "what-ifs" in the past. At the time, they served their purposes. Today, we still make speculations on things we don't know as absolute facts. But I think such speculating can be useful to stimulate thoughts, ideas and views to search for answers that may possibly serve as building blocks for the future. Just because some things are speculative, we might not want to dismiss them so quickly as being useless or unreasonable. We're all here to share and learn.
Thank you for your reply, I love questions and especially constructive ones such as yours. I dont take offense whatsoever to your asking for clarification! That's what science is about -- sharing ideas and always improving.
Quote:
Originally Posted by NightBazaar
Ben, you said you're a physicist. Experimental or theoretical? Both are important.
If asked to pick one I would side on the theoretical side. I'm part of a team that reviews papers submitted to journals on both the theoretical side and the experimental side. I look for inaccuracies and errors and things of that nature. The ones that pass the test so to say, are then allowed to be published. So I must say its a bit of both. Jack of all trades, master of none.
Quote:
Originally Posted by NightBazaar
On Page 1, Post 3, you said:
How would anyone really know? Space may surround matter, but I don't think we can simply assume that if matter is not present, space couldn't exist. We don't know. If there was no matter, there'd be no points of reference for us to use in space. Maybe a better way to say that, along those lines, is that the space of the universe we live in contains matter.
Space exists where matter is present is what I wrote. And it is true, everywhere we see matter, there's space around it. A vacuum is considered empty space for the most part. There's two types of vacuums. The first is a QED vacuum and the next is a QCD vacuum.
QED is the acronym for Quantum Electrodynamics. In a QED vacuum, there's no matter, no photons, no gravitons. As you can imagine, this is impossible to achieve experimentally as everywhere we can be to test this there is gravity and there is radiation, at a minimum, from the cosmic microwave background. Virtual particles, which do have an energy, are popping into and out of existence. And where that is, there is space.
QCD is the acronym for Quantum Chromodynamics. This is a much more complex state where multiple states can occur simultaneously.
What is important is that the entire observable Universe is full of photons, neutrinos and dark energy so there is no real "empty space".
Since space is created by the physical process of the Big Bang, "outside" of the Universe there should be no space. Space only exists where matter is present.
Quote:
Originally Posted by NightBazaar
In the same post you said:
Although your point is certainly valid, 'bubble universes' (a multiverse scenario) are completely unknown to us. We have no idea if there are any other universe-sized structures apart from our own, nor do we have any idea that "Sometimes they touch and interact." That puts it into area of speculation, prefaced by the word "If..."
So how is addressing scenarios about spacecrafts that are torus-shaped or encapsulated in a bubble of spacetime any different than scenarios about bubble universes or whether or not space exists where matter is present?
Don't take that as being an unfair criticism because I think the thread is an excellent one. But I do think it's fair to say that we don't know everything about the universe, and what we do know is subject to change based on new discoveries and information. For example, we're learning new things about the farthest reaches of the solar system that we never knew before that are changing our views. We're learning more about what the surface of Mars is really like. It was almost shocking to see all the craters in the images of the first fly-bys. And we've been learning more about the structure of the universe. We know that the sun does not orbit the Earth and that the galaxy is not the entire universe. We're learning how amazing and at the same time strange the universe is.
Sometimes the things we know about were built on speculations and "what-ifs" in the past. At the time, they served their purposes. Today, we still make speculations on things we don't know as absolute facts. But I think such speculating can be useful to stimulate thoughts, ideas and views to search for answers that may possibly serve as building blocks for the future. Just because some things are speculative, we might not want to dismiss them so quickly as being useless or unreasonable. We're all here to share and learn.
Bubble Universes and the Multiverse didn't come to theory as a result of us inventing it. The Big Bang by itself implies multiple Universes and we're pretty certain the Big Bang is real. Just like how time travel is implied by relativity.
Now the travel through space in with things we dont even know exist nor how to control if they did is a different matter. There's simply too much speculation to consider it a viable theory. Will this change? Yes, in time. In time we'll know for sure the more research is done and the more experiments occur. For today, its simply fun to think about and consider when we have more data to know if we were on the right track or not.
After all, the Higgs Boson was't really even considered until we developed enough technology to build the Large Hadron Collider and search for it. However in contrast, the Higgs Boson made sense if experiments could confirm it, which they have. So most certainly, a lot of what we have today was speculated by the previous generation.
In a previous post you'll see where I talked about how a "Yes" or a "No" isn't really yes or no, but a best estimate of the probability based on what we think we know.
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Quote:
Originally Posted by beninfl
Ask me anything physics related! I'll keep to laymans terms and no math if possible. :-) Choose from cosmology to string theory. What about the Universe doesnt make sense? Black holes? Quantum electrodynamics? Planetary formation? M-Theory and Branes? Higgs Boson? Quantum tunneling?
Lets see where the conversation goes! :-) And if you are reading a question yet to be answered and you know the answer, chime in too! Lets try to make this the longest Science thread ever on city-data.
Ben the Physicist
at what stage in a stars life does it first emit light?
at what stage in a stars life does it first emit light?
Stars start out as a gas cloud of primarily hydrogen. The hydrogen gets compressed by gravity that it starts to collapse the cloud of hydrogen, and turns into a star. In our Sun, it takes about 100,000 years (there's some discussion of this still) for the light from the center of the star to exit the Sun and begin its travels to Earth. The process is a bit more involved than this, but this is the basics in layman's terms.
Photons have existed since the beginning. Just around 380,000 years after the Big Bang, electrically neutral atoms began to form, and the universe became transparent to light as the photons were now able to travel freely with no ionized atoms in the way. The cosmic microwave background radiation is the greatly cooled remnant of these photons.
Also, I don't believe it is correct to say that "the universe" is expanding faster than the speed of light. Objects that are close to each other (cosmologically speaking) are gravitationally bound and are not receding from each other, or may even be moving toward each other (like the Milky Way and Andromeda galaxies). It is only objects that are far enough away from each other not to be gravitationally bound that are receding, and the apparent speed of recession increases with the distance. I've always liked this image:
Just remember that our particular loaf of bread may very well be infinite in spacial extent. Also keep in mind that terms like "recession" or "moving apart" aren't strictly accurate. Things aren't really moving away from each other per se, but the space (literally) between them is growing larger.
at what stage in a stars life does it first emit light?
Stellar evolution begins with the gravitational collapse of a giant molecular cloud. Typical giant molecular clouds are roughly 100 light-years across and contain up to 6,000,000 solar masses. As it collapses, the giant molecular cloud breaks into smaller and smaller pieces. In each of these fragments, the collapsing gas releases gravitational potential energy as heat. As its temperature and pressure increase, a fragment condenses into a rotating sphere of superhot gas known as a protostar. When temperatures reach 10 million degrees Kelvin. At this point a proton-proton chain will be initiated allowing hydrogen to begin fusing, first into deuterium then into helium.
When a new star is born it is called a protostar. When the protostar reaches about ten million years in age, it will start emitting light in the visible spectrum. Prior to that, the protostar emits its radiation in the form of infrared.
Depending on the density of the star, it could take anywhere from 100,000 to 1,000,000 years for a photon to escape the star and be emitted as light. This is more commonly known as the solar photon "random walk." A photon will be emitted as a result of hydrogen fusion then be absorbed by another hydrogen atom and re-emitted trillions of times before reaching the photosphere of the star. The denser the star, the longer it takes for a photon to emerge as light.
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There's simply too much speculation to consider it a viable theory. Will this change? Yes, in time. In time we'll know for sure the more research is done and the more experiments occur. For today, its simply fun to think about and consider when we have more data to know if we were on the right track or not.
