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### Science and Astronomy Questions

Posted: 18 Jan 2019 05:46
Ah no Wat, I meant to look at one's own past, sort of like a video recording of things that happened in the past, without the ability to change them.  That was in an Asimov short story.  The viewer was able to see events in history without being able to interact with or change history.

Wat, based on that, it sounds like using the special relativity speed method would be easier than trying to manufacture a source of gravity that strong- you cant get that close to a micro black hole without being destroyed

Stellator- I like the two gravity field method but based on Wat's calculations it sounds like that would be beyond our level of technology for a long time.

Uploading our minds sounds like a better idea, as long as our bodies at home get to share in the experiences!

So based on how long each method would last- would you say a few hundred years for suspended animation/croygenics, a few thousand years for the gravity field method and virtually unlimited for the uploading method?

Ha I love that term "meatsack" I remember it from Supernatural.  And transhumanism's time has come as well as lifting up animals!

### Science and Astronomy Questions

Posted: 18 Jan 2019 06:22
A different spin on the question:  What is the most time dilation we could get by accelerating at 1g?

If we find a 10 billion solar mass black hole (about the most massive that we know of), then hovering at 12.66 horizon radii would yield about 9.8m/s2 of gravitational acceleration, with a time dilation factor of 1.042, which would mean our clocks tick 2.5 seconds per minute (or about 1 hour per day) slower than clocks far away.

The same time dilation factor around SgrA* (4x106 solar masses) would require an acceleration of 6.8x107 m/s2, which is much less practical.  So the black hole's mass matters a lot.

In terms of special relativity, this time dilation factor would occur at 28.1% of the speed of light.

A-L-E-X wrote:
Source of the post Ah no Wat, I meant to look at one's own past, sort of like a video recording of things that happened in the past, without the ability to change them.  That was in an Asimov short story.

I know.  But you can't.  So I answer in the closest way that nature allows.

### Science and Astronomy Questions

Posted: 18 Jan 2019 17:00
A-L-E-X wrote:
Source of the post So based on how long each method would last- would you say a few hundred years for suspended animation/croygenics, a few thousand years for the gravity field method and virtually unlimited for the uploading method?

Well, there are significant biological hurdles to overcome before any type of stasis is considered. Any form of hibernation (deep comatose states induced by technology), 'freezing' or suspended animation will be tricky to perfect - moreso for each increase in the timelines considered for operation. Ultimately this might be another sci-fi troupe with no real application in reality simply due to so many engineering complications accompanying it. It might only be very niche or just impossible like FTL.

That being said, it really depends on the technology we use. Very advanced civilizations with metamaterials and cybernetical medical sciences could probably engineer a plethora of stasis designs - if they need them. If you are mostly or completely cyborgs or uploaded consciousnesses then stasis is a meaningless term. The durability of the technology, rather then the entity using it, is at question.

### Science and Astronomy Questions

Posted: 19 Jan 2019 01:28
Wat, so either method is pretty impractical at this point or at any point in the foreseeable future   The fastest we can accelerate to in the foreseeable future would be the 0.2c which was targeted by the Icarus Project and 100 year Starship Program.

Stellator, in that case it's a lot of wasted money by those rich folks who have been having their bodies frozen upon death, hoping for science to advance far enough that they may be cured and woken up from their cryogenic slumber.  Likely, they will be far too damaged to be recovered no matter how far science advances by then.

The cyborg option is far better for the durability question you mention.  As for FTL, I still favor some sort of Alcubierre-like solution in the very distant future for out species if we dont go extinct first.  It isn't really FTL but a way to warp the rules a bit (so to type lol.)

### Science and Astronomy Questions

Posted: 19 Jan 2019 15:33
A-L-E-X wrote:
What I wouldn't give for a Star Trek type tractor beam right now..... (is that scientifically feasible in the future)?

As with most such concepts in science fiction, it can be duplicated in reality, but not identically for engineering reasons. Scientists in Spain a while back made a device that could levitate and move around objects above it via ultrasonic soundwaves, it's more of a 'pusher' beam though.

Obviously this design has limited application in space due to a lack of medium for the soundwaves to travel through.

Over the Pond, NASA is working on a laser-based tractor-beam type piece of technology: https://www.nasa.gov/topics/technology/features/tractor-beam.html

### Science and Astronomy Questions

Posted: 20 Jan 2019 02:50
Using a laser as a "tractor beam" is surprisingly easy to do at home, provided a laser with sufficiently high power, adjustable focus, and a good Gaussian beam profile.  The way this works is due to the momentum carried by light, and small objects can be levitated and even moved around with great effectiveness.  The experiment demonstrating this effect (Optical Tweezers) also won the Nobel Prize in Physics last year.

A fun youtube demonstration (looks like clickbait but is actually a pretty good channel).

### Science and Astronomy Questions

Posted: 20 Jan 2019 03:21
Thanks, we're finding new uses for lasers all the time!  That new starship project we talked about a few months back also involved lasers, pushing along solar sails to around 0.2c.  So this would be the reverse of that?

### Science and Astronomy Questions

Posted: 20 Jan 2019 03:52
It is much easier to accelerate something to 0.2c by laser than it is to accelerate it to -0.2c (i.e. pull back towards you that fast).  The latter would be like shooting a bullet at a target and expecting the target to fly straight back at you.  Doesn't work that way, since momentum must be conserved.

That small objects can be stably levitated in a laser beam (not drifting out of it), or even moved around with the beam, is very surprising.  A small enough object diffracts the light waves around it, and when you work through the math it turns out that the object will migrate to the most intense part of the beam.  If the beam comes down to a focused point, then the object will migrate to that focus, too.  So if you slowly pull the focus back towards you then this acts like a tractor beam "pulling".  But it's not really pulling it so much as changing the equilibrium point where the object wants to be.

### Science and Astronomy Questions

Posted: 20 Jan 2019 04:42
Wat, your words are excellent at forming an image in my mind.  I pictured manually focusing on a distant target with my camera, or slowly focusing with a telescope (SCT's take particularly long to focus because of their long focus travel, unless you use a motorized focuser) and it actually seems like the way you wrote it is exactly what happens.  The object slowly floats into focus, but once in focus, it's tack sharp and motionless and just appears to hover in midair!

How strong would the laser have to be to stop that object from moving away or even just slowing it down enough so we could study it further?  Is it a function of how far away from the object the source of the laser is as well as how strong and large it is and also the object's size, mass and velocity?

### Science and Astronomy Questions

Posted: 20 Jan 2019 06:41
A-L-E-X wrote:
Source of the post How strong would the laser have to be to stop that object from moving away or even just slowing it down enough so we could study it further?

Assuming you're referring to 'Oumuamua?  It would have to be so strong that it would generate particle/antiparticle pairs out of the vacuum (I'm not even kidding).  Also, 'Oumuamua would be vaporized, making it more difficult to study.

### Science and Astronomy Questions

Posted: 20 Jan 2019 06:53
Watsisname wrote:
Source of the post Also, 'Oumuamua would be vaporized, making it more difficult to study.

### Science and Astronomy Questions

Posted: 20 Jan 2019 18:22
Watsisname wrote:
A-L-E-X wrote:
Source of the post How strong would the laser have to be to stop that object from moving away or even just slowing it down enough so we could study it further?

Assuming you're referring to 'Oumuamua?  It would have to be so strong that it would generate particle/antiparticle pairs out of the vacuum (I'm not even kidding).  Also, 'Oumuamua would be vaporized, making it more difficult to study.

Wow talk about overkill haha.  It would be better to generate a strong gravitational field to drag it back, except according to the calculations we talked about before, doing that would be nearly impossible.

### Science and Astronomy Questions

Posted: 20 Jan 2019 20:11
Until we have developed a tractor beam that will allow us to bring back 'Oumuamua, we probably also have spaceships with which we can fly behind.
I guess in 100 years or so, the time has come.

### Science and Astronomy Questions

Posted: 20 Jan 2019 20:24
Can you calculate my latitude and longitude?

### Science and Astronomy Questions

Posted: 20 Jan 2019 23:41
I don't need to Gnargenox. I know you live somewhere in Texas  .