Time Travel: More Than Science Fiction? Part 2

In the previous article by Jianchen, we examined the possibility of time travel, and the many paradoxes that crop up when you attempt it. All of it sounds quite mysterious and if you haven't read that piece, you should do so now. Seriously, click here and go. 

Now, assuming you've read the previous article, your brain is now a puddle of goo. Considering the implications of altered histories and fractured self-terminating timelines can be a mind-warbling exercise. But luckily for us, we have a tool that allows up to examine every idea and determine the truth. 
Let's go.... SCIENCE!

So what do the laws of physics say about time travel?
In a massive surprise, the laws of science (as we know them today) do not prohibit time travel! 
But there is one major caveat. You can only travel to the future, not the past (No killing Hitler yet).

But how? This is actually a property of the (almost magical) theory of Relativity, proposed by the (one and only) Albert Einstein. Henry Reich of the popular YouTube channel Minutephysics gives a nice small introduction to ways to time travel. 
(For those who like reading more than listening, here's a text link to Wikipedia on the subject).

So let's examine those methods in a little more detail:

1. Do nothing
   We are all travelling into the future at the fairly average rate of one second per second, so it should stand to reason that we are all time travellers. But we want to be special time travellers, don't we? So let's move on to;
2. Start moving
   Now here's where it get's a little trickier.
   In the theory of Special Relativity, we first figure out that things like distance and time are not absolute (i.e There is no universal time). Durations and distances are different for everyone and depend on your point of view (a.k.a. the observer's reference frame), but certain things are constant for everyone (like the velocity of light). Using this we come to the conclusion that what we consider time and what we consider space are not different things. They are just two components of the same spacetime, and are interchangeable, depending on the observer's motion. (If your mind is a puddle of goo now, I'm sorry. Special relativity wasn't understood in a day. If you really want to dig deeper, I'd recommend reading the book "Einstein For Everyone")
   Summarising, you can exploit this theory to move faster in time, relative to someone else (which is what you wanted). But to have any significant change, like days or years, you'd have to go near  the speed of light, which at 300,000,000 m/s or 1,080,000,000 (1 billion) km/h, is fast. Extremely fast. 
   So then let's try;
3. Go up 
   Here we encounter Einstein's other famous theory of General Relativity. This deals how gravity affects spacetime. If you thought Special Relativity was confusing, this is downright obtuse. (Link for the interested). For now, you'll just have to believe me when I say that gravity makes time slow down.
   So you go up to the next floor.  When you do this, the pull of gravity on you is slightly  less than someone at a lower level, so time passes slightly slower for you than it does for the other person. But again, to have a real noticible difference, you'd need a body with far greater gravitational pull than the Earth can provide, so;
4. 5. & 6.  (Hypothetical) Rotating Universes, Infinitely Long Super-dense Spinning Cylinders and Wormholes
   All these "techniques" exploit the fact that gravity bends spacetime and use it to bend so that it runs into another place (in time). The only problem is that 1) Our Universe is not rotating 2) These contraptions require types of energy and matter that are just hypothetical ideas with no evidence. So until we get some of that, there's not much to do here.

So, if you want to time travel, you can. But only very little, unless you're very fast, or very high up.

Fast Food of Philosophy

Very rarely on Quora do you see a good discussion on the Religion topic.
Recently though, thanks to a few meta-questions, some people spoken up about their dissatisfaction and written some excellent analyses.

One quote I particularly like and want to keep for posterity is

Belief systems are the fast food of philosophy.
-Alia Caldwell

I find a special spot in my mind for extremely fitting analogies, and this tickles that perfectly.

Death by Fall? Not for a Squirrel.

Sneaky little buggers
(http://www.telegraph.co.uk/earth/earthnews/9699330/Ash-dieback-mistaken-for-squirrel-damage.html)

You've probably come across a squirrel at some point in your life.

Those furry little hyper-energetic creatures that dart hither and tither like a cat chasing a laser pointer. You know what I'm talking about.

Infamous for scurrying about in search of nuts to nibble on, most squirrels are tree dwelling species, and reside at significant heights.
With the advent of urban architechture, squirrels have also taken to bunking in urban homes and attics, settling on roofs and terraces, much to the annoyance of some of it's occupants.

But constantly living and scurrying about at heights has its dangers - specifically falling.
Now most mammals dread falls, but squirrels seem to risk them all the time? Why? Surely falling is bad for them too, right?

Wrong.
Let's see why.

First we have to understand a bit about falling objects, and the physics behind them.
In middle/high-school class, you've had to calculate the velocity of an object falling from a certain height.
But out in the real world, we have to take into account something we consistently ignore in problems - Air resistance. 

Any falling object has two forces acting on it while it falls.

• Gravity
• Aerodynamic resistance or Drag

But while the gravitational force is constant throughout it's fall, this drag increases with increase in (the square of) the velocity.

So as the velocity increases, there comes a point when the force of drag is equal to the pull of gravity. 
Since the net force on the body is zero, the body will move at a constant velocity. 
This constant velocity is special for any falling body, and is known as its terminal velocity.

No object will fall faster than it's terminal velocity, no matter what height it is dropped from.

Now, back to cute furry little things.
Squirrels, since they are small and light, means they have comparatively little pull from gravity, and since they have stretchy bodies and puffy tails, they experience a lot of drag. This means that their terminal velocity is actually quite low, and squirrels can survive impacts of that velocity.
ringing it all together. Terminal velocity is the fastest that an object will ever fall, no matter what height it is dropped from. Squirrels (unlike most other mammals) can survive impacts at their terminal velocity.

I believe I can fly....
 (http://www.stephaniegallman.com/2010/05/day-186-unwelcome-house-guest.html)

Which means no matter what height you drop a squirrel from, it will probably survive.
Though don't try flinging squirrels out of buildings just yet.

Structured Procrastination

". . . anyone can do any amount of work, provided it isn't the work he is supposed to be doing at that moment." -- Robert Benchley, in Chips off the Old Benchley, 1949"

Structured procrastination is the process of doing several marginally useful tasks with great efficiency while avoiding larger, vaguer, more distant goals.

Here's the full article. 

Well worth a read for those suffering from the infliction.

Cookie Science?

On the interplus, I came across an article from a food blog called the Food Lab, written by Kenji Lopez-Alt. The post I was interested in was about finding the recipe to create the optimal chocolate chip cookie; (a worthy quest, if there ever was one). Here is the post.

Why is the kitchen white? Is that 10 bags of flour? Have you stolen all that chocolate?! Where did these ovens come from?!! WHAT ARE YOU DOING WITH MY SPOON??!!

I'm trying to make the best cookies in the world.

Oh, ok. Carry on.

The author wanted to find a deterministic way to create cookies exactly the way he preferred them. In an attempt to do this, he launches into an impressively detailed workdown off all the essential ingredients, came up with reasonable dependencies, and was far more thorough about the details of creating the treat than I have ever seen in a kitchen related incident.

Normally I would have had a nice little chuckle, drooled a little at the sumptous pictures, felt sad about not having my own unlimited supply of cookies and moved on. But I remembered a discussion I was having with some of the blogmates a while ago, and then I asked this question.

Is this science?

The answer, of course, depends on your definition of science. 
Is this rigorous science? Hardly. There are too many variables, unmeasurable uncertainties, and a general lack of repitition.

But is this the kind of science that we want to encourage?

Quite definitely so. The first step to creating scientists and promoting scientific inquiry in general, is to start making people think like scientists. 
The way scientists assess the world, analyse information presented to them, and make decisions is a fundamentally better way to think than the usual flawed way that we approach problems.
This isn't anyone's fault. Human thinking does have its limitations, but allowing thoughts to be subject to scientific reasoning allows us to spot and weed out the errors and make better choices.

Cookie science?
Bring it on!