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Patrick Bowman
Works at Massey University
Attended University of Adelaide
Lives in Auckland, New Zealand
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Patrick Bowman

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surya raju (+surya raju)
I'm not sure how you came to ask these questions of me, nonetheless I will have a go at addressing them.

Question 1
`Please explain about time dilation. Is it really possible to "travel with time " ?'

I'm not about to provide a course in Special Relativity (a good place to start would be: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/conrel.html#c1), but I think the fundamental point is this:
When Newton constructed his mechanics, he made the assumption that all observers will agree on measurements such as the distance between two points, and the time interval between two events. These were perfectly reasonable assumptions, but are, in fact, wrong.

The twin phenomena of length contraction (the faster a ruler is moving, the shorter it is) and time dilation (the faster a clock moves, the more slowly it ticks) work together so that all observers agree on speed.

For example, an observer on Earth measures the distance to Alpha Centauri to be 4 light years. So a spaceship travelling at half the speed of light would take 8 years to get there (from the point of view of an observer on Earth). Astronauts on the spaceship measure a shorter distance to Alpha Centauri (about 3.5 light years) and the travel time is correspondingly less (about 6.9 years), but they agree with observers on the ground that they are travelling at half the speed of light.

The effect has been thoroughly tested experimentally. Some of the more famous examples are the lifetime of atmospheric muons, the Hafele and Keating experiment where clocks were flown on planes, and the use of GPS. (The last two actually include an extra effect - gravitational time dilation.)

Question2.
`Earth is moving from one place to another place and rotating around the sun. Assume, In the earth one object is jumped (100m) strait 90 degrees at one particular point in 5 minutes and falls down at that "Same point" my doubt is how is it possible . because earth is rotating with some speed .
note : At 100th meter the object gravitational force is zero ,may be i right. my question is how is it possible?'

The precise motion of a projectile, from the point of view of an observer on the ground, is indeed complicated for the reasons you have mentioned. However, so long as the motion is over a relatively short distance and time, the motion of the Earth can be neglected. Here is why: whilst the tangential speed of the Earth's surface is quite large -- and the orbital speed of the Earth greater still -- the circumference of the Earth is large enough that the motion is in an approximately straight line over the time considered. That means that the observer can be used to define a stationary (and inertial) frame of reference. The problem then reduces to a straight-forward one of kinematics (http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html). In a sense, the observer and projectile are both equally affected by the Earth's motion (as they are when they are together on the ground), so it washes out of the problem.

As for the specific problem given, the travel time for an object being thrown straight up in the air to a height of 100m above ground, then returning to Earth is about 9 seconds. And the difference in acceleration due to gravity over that distance is negligible (the distance travelled is tiny compared to the Earth's radius).

If the time/distance travelled and the required precision of the measurement is such that the Earth's motion must be taken into account, this can be dealt with by inclusion of the so-called Coriolis force and Centrifugal force. But if you're worried about those effects, you should probably also be modelling air resistance.

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Patrick Bowman

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OED's Word of the Day: pwn, v.

" trans. To inflict a humiliating defeat on (an opponent), esp. in an online game. Also: to gain unauthorized access to or compromise (a computer, network, etc.)."
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Patrick Bowman

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Patchy data and some contradictions, but still really interesting. 
The most comprehensive genomic study of Indigenous Australians to date not only confirms they are the descendants of the first people to inhabit Australia, but that there is remarkable genetic diversity across the continent.
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Patrick Bowman

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Impeccable logic. (Surprisingly SFW)
PreviousNext. lovingly rendered pictures of cocks. I made sausages with Rosemary.
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Patrick Bowman

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I think Carlo Rovelli does a great job here of saying something non-trivial about the scientific enterprise in two pages.

(via Not Even Wrong)
Abstract: In the book "String Theory and the Scientific Method", Richard Dawid describes a few of the many non-empirical arguments that motivate theoretical physicists' confidence in a theory, taking string theory as case study. I argue that excessive reliance on non-empirical evidence ...
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Patrick Bowman

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Orban takes Europe's money, then turns around and bashes the EU.
A joke party that receives no state funds is the only Hungarian group mounting a visible challenge to Viktor Orban's "hate" campaign against refugees.
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"With a characteristically satirical twist, their billboards ask: “Did you know? There is war in Syria” and “Did you know? Corruption offences are mostly committed by politicians”.

I love this, really enjoyed the article.
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Patrick Bowman

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They're clearly not making them cost enough.
 
The Onion provides a step-by-step breakdown of how a movie becomes a flop:
Despite the recent box-office failures of Exodus, Ben-Hur, and Gods Of Egypt, studios continue to fund big-budget movies they hope will achieve blockbuster success. The Onion provides a step-by-step breakdown of how one of these movies becomes a flop:
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Patrick Bowman

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I'm currently learning Hungarian on Duolingo. It's still in beta, so it's a bit rough around the edges, but it's very usable.

A friend made me aware of Duolingo a while ago, but this the first time I've used it. The system has some real strengths: the material is all in one place, feedback is instant, and there's a social media "discussion" linked to each question. But mostly, it's very easy and tempting to get a bit more done each day, which is the most important thing.
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hi one general question, Please explain about time dilation. Is it really possible to "travel with time " ?.

Question2. Earth is moving from one place to another place and rotating around the sun.
Assume, In the earth one object is jumped (100m) strait 90 degrees at one particular point in 5 minutes and falls down at that "Same point"
my doubt is how is it possible . because earth is rotating with some speed .
note : At 100th meter the object gravitational force is zero ,may be i right.
my question is how is it possible?

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On the other hand, perhaps there was an earlier migration after all.
Molecular anthropology investigators may sound like something straight out of science fiction, but their work is allowing us to uncover when our earliest ancestors moved out of Africa - and it may be earlier than we thought.
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actually SBS did a run with this, using Ernie dingor exploring his ancesty, cant remember what it was called but it was gripping.
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Patrick Bowman

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Good review of the NZO's Sweeney Todd.
Peter Hoar reviews New Zealand Opera and Victorian Opera’s production of Stephen Sondheim and Hugh Wheeler’s Sweeney Todd. It stars Teddy Tahu Rhodes as Sweeney Todd and Australian soprano Antoinette Halloran in the role of Mrs Lovatt.
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yes I would be interested and I am wondering about the timing, the last production I saw was just too fast and lost the language.
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Patrick Bowman

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Russell was writing during the Great Depression, but with continuing progress in automation it is surely even more relevant today. And a great read :) 
Like most of my generation, I was brought up on the saying: 'Satan finds some mischief for idle hands to do.' Being a highly virtuous child, I believed all that I was told, and acquired a conscience which has kept me working hard down to the present moment. But although my conscience has ...
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Patrick Bowman

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Traditional welcome to country.

[H/t +Ian Borchardt]
 
What do you do if you're a non-venomous animal in Australia?

You use venomous friends as allies in the war against humanity.
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:-)

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Patrick's Collections
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Work
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  • Massey University
    Senior Lecturer, 2006 - present
  • Florida State University
    Postdoc, 2000 - 2002
  • University of Adelaide
    Postdoc, 2002 - 2003
  • Indiana University
    Postdoc, 2003 - 2006
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Currently
Auckland, New Zealand
Previously
Adelaide, South Australia - Tallahassee, Florida - Bloomington, Indiana
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Immune to kryptonite
Introduction
Theoretical physicist, Mediaeval recreator
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Am physicist
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  • University of Adelaide
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